STATE GEOLOGICAL SURVEY. Governor C. S. Deneen, T. C. Chamberlin, E. J. James, Commissioners; H. Foster Bain, Director. Contributions TO THE Stratigraphy of Illinois The Salem Lime^one ■ i I- ^ f k ^ BY . STUART WELLER Lower Paleozoic Stratigraphy of Southwe^ern Illinois BY T. E. SAVAGE Notes on Shoal Creek Lime^one BY JON UDDEN [From Bulletin No. 8. Yearbook for 1907.] URBANA University of Illinois. 1908 557 J — \ 'pj THE SALEM LIMESTONE. (By Stuabt Weller.) Contents. Introduction Relationship to the Warsaw formation 'of Hall Relationship to the St. Louis limestone The Meramec group of Ulrich Geographic distribution in Illinois ^ Hancock county St. Clair county, Monroe county . Jackson county. Union county . . . Conclusion . , . Appendix RagR 82 83 88 90 90 90 90 91 93 94 97 97 98 98 P 37 ^99 8i —6 G. S 82 YEAR BOOK FOR I907. [Bull. No. 8 Introduction. The '‘Bedford limestone” of Indiana is one of the best known and most widely used building stones in the United States at the present time. The distribution of this limestone in Indiana has been shown by Hopkins and Siebenthal,* in the reports of the Geological Survey of that state, and the same authors have described the occurrence and characteristics of the stone, and the methods of conducting the quarrying operations. In their report these authors have used the trade name “Bedford” as the name of the entire formation which is called the Bedford limestone, but this useage is apparently ill-advised because of the prior use of the name Bedford for a formation in Ohio at the base of the Mississippian.f Cumings has proposed the name Salem limestone^ as a substitute for the Bedford limestone of Hop- kins and Siebenthal, and that name is adopted in the present paper. Ulrich has rejected both the names Bedford and Salem, and uses the name Spergen limestone§ for the formation, but the substitution of Spergen for Salem seems to be wholly unwarranted. The fauna of the Salem limestone has long been a notable one in the literature of American paleontology, because of the remarkable condition of preservation of the fossils in certain of the Indiana locali- ties, and because of the great numbers of individuals. The fauna was first described by Hall, chiefly from material collected at Spergen Hill and Bloomington, Indiana, || but without illustrations, the beds furnish- ing the fossils being referred to the Warsaw limestone of the Missis- sippi river section. At a later date Whitfieldlf republished Hall’s orig- inal descriptions of these Indiana fossils with additional notes, accom- panied by illustrations drawn from the original type specimens. Still later Hall republished his original paper with additional notes, accom- panying the paper by the same plates of illustrations which were pub- lished by Whitfield.** These three papers gave to this fauna such notoriety that it has been commonly spoken of as the Spergen Hill fauna, and had not Cumings previously used the name Salem, Ulrich’s name, Spergen limestone, would have been highly appropriate as a name for the formation. •The Bedford Oolitic Limestone, by T. C. Hopkins and C. E. Siehenthal. 21st Ann. Rep Ind. State Geol. pp. 289-427 (1896). tFor a discussion of the usage of the name Bedford see remarks by Cumings, Siebenthal, Chamberlin and Prosser, Jour-, Geol., vol, 9, pp. 232-235. 267-271; also Revised Nomenclature of the Ohio Geological Formations, by Charles S. Prosser, Geol. Surv. Ohio, 4th ser.. Bull. No. 7, pp. 19-20. fjour. Geol., vol. 9, p. 233, (1901.) §The Lead Zinc and Fluorspar Deposits of Western Kentucky, by E. O. Ulrich and W. S. Tangier Smith, U. S. G. S.. Prof. Pap., No. 36, pp. 28-30, (1905.) I] Trans. Albany Inst, vol. 4, pp. 2-36 (1856). if Bull. Am. Mus. Nat Hist, vol. 1, pp. 39-97, plates 6-9 (1882). **12th Ann. Rep. Ind. State Geol., pp. 319-375, plates 29-32 (1883). Weller.] THE SALEM LIMESTONE. 83 A peculiar feature of the Spergen Hill fauna as it was described by Hall and by Whitfield, is the diminutive form of most of the species, but further investigation of the fauna in other localities has shown that many of them often attain larger and more nearly normal propor- tions, and that many of the forms have a wide geographic distribu- tion. In connection with these later investigations, many additional species have been recognized in the fauna, which have been described by various authors in various places, and have usually been recorded as from either the Warsaw or the St. Louis limestone. The latest contribution to our knowledge of this fauna is a paper entitled “The Fauna of the Salem Limestone of Indiana,”* which has been contrib- uted to by E. R. Cumings, J. W. Beede, E. B. Branson and E. A. Smith. In this paper an attempt has been made to gather together in one place, all information available concerning the fauna as it occurs in Indiana. In the present paper the occurrence of this formation in Illinois will be discussed. Its relations to the other formations of the Mississippian series will be considered, as well as its general physical characters, its geographic distribution, and its possible utilization as a building stone. No attempt will be made to describe in detail the fauna as it occurs in Illinois, but as complete lists of species as can be made at the present time, will be given in an appendix, for the various localities from which fossils have been collected. Relation of the Salem Limestone to the Warsaw Formation . OF Hall. It has long been recognized that certain limestone beds in Illinois contain representatives of the Spergen Hill fauna of Indiana, indeed, one locality above Alton was frequently mentioned by Hall in his record of the geographic distribution of the species in the original description of the fauna. This locality was referred by Hall to the Warsaw limestone formation, as were also the beds in Indiana bearing the Spergen Hill fauna. The typical section of the Warsaw limestone, at Warsaw, Hancock county, Illinois, as given by Hall, is as follows:! Feet. 3. Coarse calcareous yellow sandstone, in thick heavy beds, quarried for building. 2. Argillaceous limestone with shaly partings, containing abundance of large Archimedes and other bryozoa; thickness at Warsaw 25 1. Magnesian limestone of variable thickness, and sometimes absent. Worthen did not recognize the Warsaw limestone as a distinct major division of the Mississippian in Illinois, but included all the beds so designated by Hall in the “St. Louis Group,” extending this interpre- tation to the limestone beds above Alton and to those at Spergen Hill * 3\)th Ann. Rep. Ind. State Geol., pp. 1187-1486, plates 7-47 (1906). t Geol. Surv., Iowa, vol. 1, pt. 1, p. 161. 84 YEAR BOOK FOR I 907 . [Bull. No. 8 and Bloomington, Indiana.* In his report on Hancock county, Worthen has as usual considered the beds comprising the typical Warsaw formation of Hall as a part of the St. Louis lirriestone and has given the following section of the beds as exposed at the typical locality, f Feet. 4. Concretionary and brecciated limestone 10-30 3. Calcareous grit stone 10 2. Blue shales and Archimedes limestone 20 1. Magnesian limestone: 8-12 The beds i, 2 and 3 in Worthen’s section are identical with those given the same numbers in Halhs section ; No. 4 of Worthen’s section being the only bed at this point included in the St. Louis by Hall. In Worthen’s section the thickness of beds i and 3 are mentioned, giving to the entire Warsaw formation of Hall a thickness of something over 40 feet. Hall mentions the thickness of the median member of his formation only, and he considers this bed to be the typical expression of his formation, faunally and physically, and in his table of forma- tionsj he would apparently restrict the name “Warsaw limestone” to this median bed alone, and correlate with it the limestone above Alton and the beds at Spergen Hill and Bloomington, Indiana. In a study of the Warsaw locality by the writer the following sec- tion, which agrees essentially with those published by both Hall and Worthen, although worked out in greater detail, was carefully meas- ured along the creek east of the town. Feet. 11. Dense, bluish, brecciated limestone 10 10. More or less cross-bedded limestone, yellow on weathered surfaces and granular in appearance, containing large numbers of broken bryozoans; sometimes replaced by a calcareous grit or sandstone.. 8 9. Thin-bedded bluish limestone, interbedded with calcareous shales. Fossil bryozoans abundant, especially Lioclema punctata and Arch- imedes wortheni 18 8. Fine blue shale 3 7. Hard, light-colored limestone, with few poorly preserved fossils.... 4 6. Fine blue shale 8 5. Magnesian limestone with shaly bands. Fossils poorly preserved, usually rare, mostly bryozoans 8 4. Bluish shales with numerous geodes which are usually smaller than those in the magnesian limestone beds below 21 3. Magnesian limestone with chert bands 3 2. Magnesian limestone with numerous geodes. Some beds more or less shaly. Geodes most numerous in the middle part of the bed. Fossils poorly preserved and rather rare, mostly imperfect bryo- zoans 15 1. Blue or grey crystalline limestone with many fossils. Thickness not known, the bed extending below river level (exposed) 15 In this section beds 5 to 10 inclusive comprise the original Warsaw formation of Hall, Bed No. 9 being the typical Warsaw limestone of that author, containing the large numbers Archimedes and other bryo- zoans. Bed No. 10 is the calcareous grit stone, No. 3, of both the * Geol. Snrv. 111. vol. 1, pp. 8:?-84 ; also Econ. Geol. 111. vol. 1, p. 65. t Geol. Surv. 111. vol. 1, p. .*1:18 : also Econ. Geol. 111., vol. 1. pp. 270-71. j Geol. Surv. Iowa, vol 1, pt. 1, p. 109. ^YELLER.] THE SALEM LIMESTONE. 85 Hall section and'the Worthen section. This bed is exceedingly vari- able in character, being at times a nearly pure, cross-bedded limestone, as at the quarry back of the school building at Warsaw, again it is a sandstone or a calcareous grit stone. Hall mentions the occurrence of small quartz pebbles in some places. When the formation is calcare- ous the weathered surfaces exhibit great numbers of broken bryozoans, more or less imperfectly preserved, and a few brachiopods. The fauna from the quarry near the school house, already mentioned, is as follows : RMpidomella duhia (Hall). Spirifer suhaequalis (Hall). Fenestella serratula (Ulr). Fenestella multispinosa (Ulr). Rhoml)opora (sp). Gystodictya lineata (Ulr). WortTienopora spinosa (Ulr). The fauna is notable for the entire absence of Archimedes, Glyp- topora and Lioclema, genera which are most conspicuous in the fauna of the subjacent thin-bedded limestones and shales. On the other hand, all the species recognized here occur commonly and are usually among the more abundant in the limestones further south, near Alton and elsewhere, which Hall considered as representative of his Warsaw limestone. Some or all of the species also occur more or less sparingly in the subjacent bed associated with the abundantly represented genera mentioned above. It is evident, therefore, that although this uppermost member of the Warsaw, as defined by Hall, is somewhat closely related, faunally, to the subjacent and more typi- cal member of the Warsaw group, it is this upper member rather than the typical Archimedes and Lioclema bearing bed which is to be correlated with the so-called Warsaw limestone above Alton and else- where. Like the fauna of this bed at Warsaw, so the fauna of the limestone farther south is notable for the extreme rarity and usually by the entire absence of members of the genera Archimedes, Glyp- fopora and Lioclema, and with the possible exception of Lioclema, the species of these genera which do rarely occur are usually if not always distinct from those of the Archimedes bearing bed at Warsaw. The locality in the region to the south of Warsaw where the beds under discussion are best exhibited for study is not above Alton, although that is one of the best fossil localities, but is in Missouri, in the neighborhood of Meramec Highlands west of St. Louis, The following section at this locality is compiled from several carefully measured se.ctions in the bluffs of the Meramec river and up the tribu- tary valley to the large quarry by the Frisco Railroad track east of the Meramec Highlands station: Feet. 17. Grey, granular or compact limestone, the successive beds more or less variable in character, with numerous horizontal chert hands. Fossils rare. The top of this limestone extends to the crusher plant at the quarry, by the railroad track 40 16. Massive, granular, gray limestone with few fossils 10 15. Shaly magnesian beds 2 86 * YEAR BOOK FOR I907. [Bull. No. 8 14. Limestone filled with fossils of the Spergen Hill fauna 5 13. Limestone, somewhat shaly and magnesian in places 7 12. Fossiliferous limestone with typical Spergen Hill fauna 2 11. Limestone, similar to that above 4 10. Yellowish limestone filled with examples of a Rhynchonelloid shell. . 2-6 9. Limestone beds, often yellowish in color, some beds shaley and ap- parently somewhat magnesian, other beds filled with bryozoans and other fossils 30 8. No outcrops, talus probably underlain by shale in the lower part and limestone above 26 7. Shale exposed 2 6. No outcrops, probably shale 13 5. Blue shale, fossiliferous, Lioclema punctata, one of the most con- spicuous species 4 4. Blue crystalline limestone with many Spirifers at top 4 3. No outcrops, probably shales in large part 18 2. Shaly beds with intercalated cherty limestones 9 1. Blue or gray, more or less crystalline limestone, with much chert. . . 29 In this section three rather well defined divisions may be recognized. The first division includes Beds No. i and No. 2 and is well exposed along the base of the bluff to the south of Meramec highlands. It consists of extremely cherty limestones which are free from shale partings below but with more and more conspicuous shale partings, and beds above. These beds are exposed to the extent of 38 feet in the measured section recorded above, but all these beds rise to the north and near the abrupt bend in the river some 60 feet are exposed. The second, next higher division consists largely of shales or shaly limestone as is evidenced by the nearly complete talus covering. Only occasionally, where small ravines have been cut into the bluff, are the b6ds exposed. No examples of Archimedes wortheni have been ob- served in this bed, but Lioclema punctata does occur in abundance where fossils' have been collected. This talus covered slope between the limestone outcrops below and above, is a conspicuous feature in the bluffs along the river to the south of Meramec high lands. The thickness of this bed is not accurately known since the talus is banked up against the basal part of the superjacent lime- stone, obscuring the lower beds of that division, but measured from the top of the lower division to the first exposures of the limestone of the upper division, there are 67 feet, which is doubtless too great, the excess possibly being as much as 20 feet. The third division is best exposed in the quarry already mentioned and comprises beds 9 to 16, inclusive. The basal part of it is also well seen in the upper portion of the river bluffs. The beds of this di- vision are more or less variable in character, some of them being highly fossiliferous, the fauna being the typical Spergen Hill fauna. Some of the beds near the base are not unlike, in their lithologic charac- ters, the calcareous facies of the uppermost division of the Warsaw group in Hancock county, Illinois. These beds are also well exposed in the cuts along the Frisco railroad between Meramec Highlands and Keyes Summit, and again at the tunnels of the Missouri Pacific rail- road at Barrett’s Station. Bed No. 17, in the general section here de- scribed, differs from the subjacent limestone beds in its different litho- logic characters, in the almost entire absence of fossils and in the presence of chert; it is in fact the basal portion of the true St. Louis limestone and need not be considered in the present discussion. Weller.] THE SALEM LIMESTONE. 87 In the section above Alton in the Mississippi river bluffs, the con- ditions are essentially the same as those at Meramec Highlands, al- though the continuity of the beds from the cherty limestones below with shale partings, through the more shaly beds of the second division to the limestone at the summit is not so well shown because of the erosion of the Piasa creek. In the first exposures in the bluff east of the mouth of Piasa creek near Lock Haven, the uppermost beds of the shaly division are exposed, followed by the limestones bearing the Spergen Hill fauna. These beds with an easterly dip are then more or less continuously exposed in the base of the river bluff to Hopp Hollow above Alton where they pass below the superjacent limestones, their total thickness being from 90 to 100 feet. In correlating the Meramec Highlands section and that in the Mississippi river bluff above Alton, with the section at Warsaw, the evidence indicates that the uppermost bed in the Warsaw section, the calcareous grit stone of Worthen and of Hall, with a thickness not exceeding 10 feet, increases in thickness to the south until it attains a depth of approximately 100 feet in the neighborhood of Alton and St. Louis. In this respect this bed resembles the typical St. Louis lime- stone which becomes much attenuated in thickness to the north. The more typical expression of the Warsaw formation of Hall, com- prising the blue shales with intercalated thin limestone beds, with the Archimedes and Lioclema fauna, extends to the south with no great variation in thickness where it is exhibited in the more or less talus covered shaly bed in the Meramec Highlands section. The geode beds of the Warsaw section, usually considered as the upper limit of the Keokuk limestone, are not present in the more southern region, the higher Keokuk beds being represented by the cherty lim- stones with shale intercalations in the Meramec Highlands section. The original Warsaw formation of Hall is therefore two-fold in its nature ; the upper division being of but subordinate importance in the typical section, but increasing in thickness to the south until it en- tirely overshadows the lower and more typical beds. In making such a division of the original formation the name Warsaw may be re- stricted to the lower, more typical part which includes much the larger portion of the beds in the type section. The upper division, as it is followed to the south from Warsaw, becomes an important limestone formation which is everywhere characterized by the Spergen Hill fauna of Indiana, and may be definitely correlated with the Salem limestone of that state. The dual nature of the beds referred to the Warsaw formation by various authors was recognized by Williams*, although he was unable to straighten out the confusion from a study of the literature alone. Keyesf also recognized the same fact and united all the beds of Hall’s original section 'with the Keokuk, while the so-called Warsaw lime- stones above Alton and elsewhere were considered as forming the basal portion of the, St. Louis limestone. He failed to recognize the • Bull. U. S. G. S. No. 80, p. 169 (1891). t Iowa G. S., vol. 1, pp. 70-71 (1893). YEAR BOOK FOR I 907 . [Bull. No. 8 fact, however, that these limestone to the south were really the more expanded extension of the subordinate upper member of the Warsaw formation in its typical section. Relationship of Salem Limestone to St. Louis Limestone. The name St. Louis limestone was first applied by Englemann* to the limestones which underlie ‘hhe western edge of the great Illinois coal filed.” The definition of the formation was inadequate according to recent standards, and the stratigraphic relations of the beds were mis- understood since the formation was supposed to' overlie those beds which we now call Cypress sandstone and Chester instead of being subjacent to them as is now known to be the case. In the 1855 Report of the Geological Survey of Missouri, both Swal- low and Shumard discuss the St. Louis limestone, and both are in accord in their interpretation of the formation. The best exposition of the conception of this limestone formation held by these men is given in Shumard’s report on St. Louis County, f in the description of the geologic section along the line of the Pacific Railroad, now the Missouri Pacific Railroad. In this description the beds exposed at both tunnels at Barrett’s Station, which beds are referred tO' the .Salem limestone in this paper, are distinctly described as belonging to the “Archimedes limestone,” a formation subjacent to the St. Louis lime- stone, and this relation is clearly shown in the graphic section accom- panying the report. In the description of the Archimedes limestone by Swallow! the strata on the Des Moines river and near Keokuk, Iowa, are mentioned in such a manner as to show clearly that his Archimedes limestone is considered as essentially the equivalent of the beds called Warsaw by Hall at a later date. It is clear then that these authors who were the first to define the St. Louis limestone in a manner at all adequate excluded from that formation these beds which we call Salem limestone. Hall’s interpretation of these beds has already been discussed. He followed essentially the interpretation of Swallow and Shumard, and considered this formation as distinct from the St. Louis limestone, call- ing it the Warsaw limestone. Worthen departed from the interpretation of these earlier geologists and considered the beds under discussion as a part of his St. Louis group, § and included also under this head the typical Warsaw lime- stone of Hancock county. It is clear, however, that Worthen did not intend to completely dispense with the name Warsaw as a formation name as he not infrequently mentioned the Warsaw division of the St. Louis in his county reports, but he at no time distinguished between the typical Warsaw as that formation would be restricted by the writer and the higher division here called the Salem limestone. Wor- then’s usage of St. Louis as a group name in which was included a * Am. Jour. Sci. 2nd Ser. ; vol. 3, p. 119 (1847). list and 2nd Ann. Rep. Geol. Surv., Mo., pt. 2, p. 169, (1855.) tLoc. cit.. pt. 1. p. 95. §Geol. Surv. 111., vol. 1, p. 83 (1866); also Econ. Geol. 111., vol. 1, p. 65, (1882.) Weller.] THE SALEM LIMESTONE. 89 subordinate division, the St. Louis limestone proper, has led to some confusion among more recent authors, and the more general conception of late years has been that the St. Louis limestone in its original defi- nition included all these limestones under consideration. Extended field observations by the writer have shown that the Salem limestone is as clearly defined a stratigraphic unit in the Mississippian series of the Mississippi valley as any of the formations recognized. The formation may be easily distinguished from the superjacent St. Louis limestone on lithologic characters alone, and when the faunal characters are considered the difference is even more striking. The formation includes beds of m.ore or less variable lithologic characters, the variable character being perhaps more pronounced in the northern than in the southern outcrops. Usually the formation is nearly or quite free from chert. Throughout its extent it contains important beds of light-colored, nearly white limestones, which are not infrequently more or less oolithic in texture. In some cases the apparent oolithic grains are the shells of a small foramifera Endothyra bailey, but again there are true oolites. These lighter colored beds have a peculiar method of weathering which is not often observed in any other of the Mississip- pian formations. The more or less vertical faces of the outcrops scale off in a transverse direction to the bedding in rather thin, irregular flakes from three to six inches across and an inch or less in thickness, this fracturing of the rock evidently being due to frost action. Fine grained, bluish grey or buff colored magnesian beds of varying thick- ness are not infrequently interbedded with the more nearly pure lime- stones, and at two localities, one in Madison county and the other in St. Clair county, beds of this character have been extensively mined for the manufacture of hydraulic cement, although the deposits have not been worked during recent years. The purer limestones in this formation are usually more or less abundantly fossiliferous, and the fossils often occur in an excellent state of preservation. Among the most conspicuous forms are the bryozoans, belonging to the genera Fenestela, Polypora and Crysto- dictya, which often present a nearly pure white color in the slightly darker matrix. The Salem limestone does not contain, at least as a conspicuous ele- ment, beds of dense, compact, bluish gray limestones with conchoidal fracture and with a texture almost of lithographic stone, such as are commonly present in the St. Louis limestone ; neither are there present the brecciated beds which are sO' characteristic of the St. Louis. The two formations may also be differentiated by reason of the abundance of fossils in the Salem and the comparative rarity of them in the St. Louis, at least in such a condition of preservation as to be readily de- termined. In fact, most of the so-called St. Louis fossils in the Missis- sippi valley are in reality from the Salem limestone. Although there is no structural break between the Salem and the St. Louis, and the sedimentation was evidently continuous from the lower to the upper formation, except in the extreme northern exten- sion of the beds where there is a possible slight uniformity, the dividing line between the two formations in any given section may usually be 90 YEAR BOOK FOR I907. [Bull. No. 8 easily recognized within a thickness of from five to ten feet. This separation may ordinarily be made on the lithographic characters alone, but with the aid of the fossils no mistake can be made. The Meramec Group of Ulrich. Ulrich has defined as the Meramec group* those beds included in the St. Louis group of Worthen, the name Meramec being substituted for St. Louis in order to avoid the usage of that name in two senses. In this group he includes the Warsaw, Spergen and St. Louis. The Warsaw formation, however, should from both physical and faunal reasons be more properly joined with the subjacent Keokuk formation, which would bring it into the Osage group, and there is no more reason for associating the Salem and the St. Louis in one larger division than in bringing the St. Louis and the superjacent St. Genevieve fonna- tions together. It would seem, therefore, that in so far as the Illinois stratigraphy is involved the recognition of a Meramec group is of doubtful utility. Geographic Distribution of Salem Limestone in Illinois. Hancock county — As has already been indicated, the northermost point where the Salem limestone has been recognized is at Warsaw, in Hancock county, where the formation is represented by a bed of grit, or arenaceous limestone of variable lithologic character, which reaches a thickness of only eight to ten feet. There is no clearly defined un- conformity at this locality upon the subjacent Warsaw limestone and shale, but the presence of the arenaceous beds which sometimes, accord- ing to Hall, contain quartz pebbles, is at least suggestive of an uncon- formity. The unconformity, however, if such be present, is only a slight one, since a numberof species of fossils are common to the War- saw formation and the superjacent Salem limestone. The species of fossils which have been identified in the Salem limestone of Hancock county have already been mentioned. McDonough, Schuyler, Adams, Brozun, Pike, Greene and Jersey counties — In these counties no examination of the Salem limestone has been made by the writer except in Adams and Calhoun. In all of them, however, the St. Louis limestone is described by Worthen, f and from reading his descriptions one can usually recognize certain of the lower beds which should doubtless be referred to the Salem lime- stone. In Adams county, where the formation has been seen, but not carefully studied the beds are similar in character to the equivalent beds further south. In Calhoun county the Salem limestone occurs *U. S. G. S.. Prof. pap. No. 36, pp. 28-34. tMcDonouffh Co.. Geol. Surv. 111., vol. 5, p. 260; also Econ. Geol. of 111. vol. 3, p. 273. Schuy- ler Co., Geol. Surv. 111. vol. 4, p. 84; also Econ. Geol., vol. 2, p. 330. Adams Co., Geol. Surv. 111. vol. 4, pp. 51-53; also Econ. Geol. 111., vol. 2, pp. 293-396. Brown Co. Geol. Surv. 111., vol. 4', pp. 68-69; also Econ. Geol. 111., vol. 2, pp. 313-314. Pike Co., Geol. Surv. 111., vol, 4, p. 32; also Econ. Geol. 111., vol. 2. p. 272. Calhoun Co., Geol., Surv. 111., vol. 4, p. 15; also Econ. Geol. 111., vol. 2, p. 25^ Greene Co., Geol. Surv. 111., vol. 3, pp 127-128; also Econ. Geol. 111., vol. 2, pp, 51-52. Jersey Co., Geol. Surv. 111., vol. 3, pp. 111-112; also Econ. Geol, 111., vol. 2, pp. 32-33. Weller. 1 THE SALEM LIMESTONE. 91 in only a single limited area adjacent to the Cap au Gres fault. The exposures are much weathered and appear to be porus, brown, mag- nesian limestone in which the fossils are imperfectly preserved.* In passing southward from Hancock county the formation becomes thicker, but does not attain its normal thickness of nearly 100 feet until Madison county is reached. Madison county — In Madison county the Salem limestone is exposed in the Mississippi river bluffs from near the mouth of Piasa creek to Hopp Hollow, two miles above Alton. In the bluffs %. mile below the mouth of Piasa creek the lower beds of the formation are exposed resting upon the subjacent 'Warsaw shales, In passing down the river higher and higher beds are exposed by reason of the gentle dip of the rocks to the' east, until, at Hopp Hollow, the formation passes be- neath the surface. A series of measured sections have been studied in these bluffs, which give the total thickness of the formation as 94 feet. The first of these sections is 54 of a mile east of the Piasa creek, above the tracks of the C. P. & St. L. Railroad, in which the following beds were recognized. Feet 13 Thin bedded limestone, very fine in texture, of grey or yellowish color; beds % to 1 inch in thickness, almost shale-like in ap pearance, 93-100 feet 7 12 Talus covered slope. 79-93 feet 14 11 Limestone of variable character, apparently more or less mag- nesian, some beds more magnesian than others. Mostly rather thin bedded, but some beds 1 foot in thickness. Partially covered with talus. 69-79 feet 10 10 Gray or buff limestone, granular in texture, heavy bedded, with scaly weathered surface. Fossils abundant. (W93). 58-69 feet 11 9 Fine grained, gray or blue magnesian bed, similar in texture to the cement bed formerly mined near Clifton. 56-58 feet 2 8 Limestone with coarse, irregular texture, with numerous crinoid stems and bryozoans showing on the weathered surface. 55-56 feet 1 7 Yellowish, impure magnesium limestone. 54-55 1 6 Fine grained granular limestone, gray or yellowish in color. Good fossils not common although the entire bed is composed of worn organic fragments. 42-54 feet 12 5 Impure, brownish limestone, more or less thin bedded. 39-42 feet. . 3 4 Yellowish, granular, crystalline limestone, with abundant fossils, some of which are well preserved. (W92). 34%-39 feet 45^ 3 Limestone similar to that above but with the fossils less per- fectly preserved. This bed is in two ledges with a shaly band between. 28-345^ feet 65^ 2 Talus slope with no exposure. 3-28 feet 25 1 Blue shale exposed a few rods above the point where the re mainder of the section was measured. 0-3 feet 3 In this section bed No. i is doubtless a part of the shaly Warsaw formation, although no fossils were secured. The talus slope between 3 and 28 feet is probably in large part underlain by the Warsaw shales, although the basal part of the superjacent Salem limestone may also be covered. Be'ds Nos. 3 to 13 are all to be included in the Salem limestone. tBull. 111. State Geol. Surv., No. 4, p. 228. 92 YEAR BOOK FOR I907. [Bull. No. 8 The next section in the series is in the bluff above Riehl’s Station, on the C., P. & St. L. railroad, where the following beds were recog- nized : Feet. 9 Granular, gray limestone, with scaly weathering, thinner bedded above, the weathered surface covered with fragmentary crinoid stems and other fossils. 54-65 feet 11 8 Oolitic limestone filled with fossils (W95). 52-54 feet 2 7 Dense, more or less irregularly bedded limestone, apparently somewhat magnesian. 47-52 feet 5 6 Granular, gray or yellowish limestone exhibiting scaly weathering. 37-47 feet 10 5 Heavy bedded limestone with many fossils. 26%-37 feet 10% 4 Limestone which is apparently in part magnesian. Fossil bryo- zoans. 24%-26% feet 2 3 Heavy ledge of limestone which is probably the same as bed No. 3 in the last section. 20-24% feet 4% 2 Limestone, variable in character with a one foot fossil band at elevation 12-13 feet (W94). 10-20 feet . 10 2 Blue, gritty shales, similar to that at the base of last section. 0-10 feet 10 The shale at the base of this section, bed No. i, is the same as the shale at the base of the last section and is doubtless a part of the Warsaw formation. The remainder of the section is entirely within the Salem limestone. Below Riehl’s Station these beds are again well exposed, although the Warsaw shales at the base soon pass below the surface because of the easterly dip of the strata. A little distance east of the railroad trestle below the station a small collection of fossils was made from No. 4 of the above section where this bed has dropped to a level of about 16 feet above the railroad track (W96), and another collection from the same locality from the same limestone just above the last, six inches to one foot in thickness (W97). The next section in this series starts from the mouth of a small ravine known as Hull’s Hollow about one and one-half miles below Clifton Terrace station, and was measured to the top of the bluff west of the ravine. The beds recognized are as follows : Feet. 15 Heavy, brecciated or conglomeratic limestone. 171-183 feet 12 14 Limestone of variable character, thick and thin beds, some layers apparently magnesian and some layers shaly. 117-171 feet.... 54 13 Brecciated limestone. 110-117 feet 7 12 Hard, gray limestone with numerous plates and spines of ArcJiaeocidaris on the weather surfaces. 102-104 feet 2 11 Hard, gray limestone. 97-102 feet 5 10 Limestone ledges more or less talus covered, some beds shaly. 61-97 feet 36 9 Hard, fossiliferous limestone (W45). 59-61 feet 2 8 Limestone, mostly in heavy beds, with some thinner shaly beds. Fossils not abundant. 38-59 feet 21 7 Buff colored, shaly, magnesian bed. 34-38 feet 4 6 Hard, fine grained, gray limestone exposed in lower part of old quarry. 26-34 feet 8 5 Talus covered. 20-26 feet 6 Weller.] THE SALEM LIMESTONE. 93 4 Gray, fossiliferous limestone forming the lower waterfall near the mouth of the ravine (W44), 10-20 feet 10 3 Hard limestone ledge, oolitic in part, with a large Spergen Hill fauna (W43). 9-10 feet 1 2 Earthy magnesian bed, with texture similar to that of the “cement bed” formerly mined near Clifton. 7-9 feet 2 1 No exposure from river level. 0-7 feet 7 In this section beds Nos. i-g may be included in the Salem lime- stone, the higher beds being a part of the St. Louis limestone. It was probably from beds Nos. 3 and 4 of this section, or from Hopp Hollow, the section next to be described, that Hall’s material mentioned as coming from above Alton in his paper on the Spergen Hill fauna of Indiana, was obtained. The oolitic portion of bed No. 3 is especially rich in fossils and contains a large portion of the same species, in a very perfect condition of preservation, as the Spergen Hill and Bloom- ington beds of Indiana. This bed is also probably the equivalent of bed No. 8 in the Riehl’s Station section, where it occurs at an elevation of from 52 to 54 feet above the railroad track. In the quarry of the Blue Grass Crusher Co., just west of Hopp Hollow, the upper beds of the Salem limestone are exposed with the superjacent St. Louis limestone. The measured section at this point is as follows : Feet. 13 Brecciated limestone. 130-142 feet 12 12 Gray to buff limestone, becoming somewhat thinner bedded above. 108-130 feet 22 11 Brown limestone. 105^-108 feet 2% 10 Dense gray limestone with numerous sections of brachiopods shown upon the weathered surface. 103%-105i/^ 2 9 Gray limestone, thin bedded in one inch layers, with occasionally brownish layers. * Ripple marked surface at elevation 83. 81-103 Va feet 22 Va 8 Limestone, heavy bedded below, becoming thinner bedded above to top of quarry. 64-81 feet 17 7 Yellow, earthy layer, probably magnesian. 60-64 feet 4 6 Impure limestone in thick and thin beds, some shaly layers, six inches of blue clay shale at the base. Towards the top the beds become thicker, being hard, dense limestone. 47-60 feet 13 5 Impure limestone with much chert, somewhat earthy in texture. Yellowish in color, probably magnisian. 34-47 -feet 13 4 Magnesian (?) limestone, shaly below. 31-34 feet 3 3 Dense limestone with some chert. 26-31 feet 5 2 Limestone similar to that below, but more dense, a little darker in color, with some hard masses and some chert. 18-26 feet 8 1 Light gray, granular limestone, with an abundance of fossils in pockets and bands. No chert (W42). 0-18 feet 18 In this section bed No. i represents the summit of the Salem lime- stone, all the higher beds being of the St. Louis limestone. The fauna of this bed is somewhat extensive and is the typical Spergen Hill fauna of Indiana. Below this quarry the Salem quickly passes out of sight by reason of the eastward dip of the strata. St. Clair county . — On the Illinois side of the Mississippi river the outcrop of the Mississippian beds is interrupted between the northern part of Madison county and the southern part of St. Clair, by the broad American bottom, the alluvial deposits extending eastward to 94 YEAR BOOK FOR I907. [Bull. No. 8 beyond the line separating the Mississippian and the Pennslyvanian series. At the point where the bluffs of Mississipian limestone re- appear in southern St. Clair county, the beds exposed are typical St. Louis limestone, with a gentle northerly dip. Following the bluffs to the south the beds arise until the Salem limestone appears in the base of the bluffs and finally constitutes nearly or quite all of the limestone beds exposed in the bluff. Before the Monroe county line is reached, however, the crest of an anticline is passed and the beds again pass beneath the surface. In the point of the hill just northwest of Sugar Loaf school house the St. Louis limestone beds of the southwestern limb of the anticline exhibit a dip of 31 degrees, which is much more abrupt than the dip of the opposite limb. In the upper part of the ravine extending back from the river at Sugar Loaf school house where the old cement mine is located, a good section is exposed, the base of the section being shown in the bank of the creek back of the house occupied by Mr. James Bergen, and the upper beds at the cement mine. Feet. 13 Ledges of thick and thin bedded limestones, more or less granular and crystalline in texture, usually light in color with gray or brown tints, some thin beds apparently magnesian and occasion- ally shaly partings. All these beds are more or less covered with talus. 47-80 feet 33 12 Cement bed. Earthy, bluish or gray magnesian limestone with uniform texture. Exactly similar in texture to the cement bed in the Salem limestone near Clifton Terrace in Madison county. 39-47 feet 8 11 Thin bedded limestones. 36-39 feet 3 10 Thin bedded blue limestone with large numbers of fossil Spirifers (W250). 35-36 feet : 1 9 Thin bedded limestone similar to the beds above. 33-35 feet. ... 2 8 Limestone similar to that above with numerous fossils (W249). 32-33 feet 1 7 Thin bedded limestone with bands of shales. 30-32 feet 2 6 Possiliferous limestone (W248). 29-30 feet 1 5 Buff or blue shales with occasional thin beds or lenses of lime- stone. 18-29 feet 11 4 Buff colored fossiliferous shales (W247). 16-18 feet 2 3 Buff or blue shales with occasional thin beds or lenses of lime- stone. 6-16 feet 10 2 Irregularly thin bedded, fossiliferous limestone strata with inter- bedded shale (W246). 4-6 feet 2 1 Blue and buff fossiliferous shales (W245) 0-4 feet 4 In this section a little over 40 feet of the higher beds including the cement bed are referable to the Salem limestone. The lower beds represent the shaly Warsaw formation as it is so well developed in St. Louis county, Missouri, and as it occurs in northern Madison county. Monroe county — A quarry in the Salem limestone was formerly worked in the southwest quarter of section 14, about a mile southeast of Columbia. At this point a thickness of about 48 feet of limestone is exposed which is more or less variable in color and texture. Its characters agree well with those of the Salem limestone exposed in the river bluffs of southern St. Clair county. In the bed of the quarry is a shaly bed which is abundantly fossiliferous, the fauna being a Weller.] THE SALEM LIMESTONE. 95 characteristic assemblage of the vSalem limestone (U 48). At another locality one and one-half miles south of Columbia, in the southeast quarter of section 27, the Salem limestone is exposed. The rock at this locality is similar in its physical and faunal characters to the beds of similar age further north. Fossils are somewhat abundant (U 56). At both of the last localities the Salem limestone has been brought to the surface by the anticlinal folding of the beds, exhibited in the river bluff in southern St. Clair county. In the Mississippi river bluffs the .Salem limestone is not exposed in Monroe county until a point south of Fountain creek is reached where the rocks begin to rise to the anticlinal axes exhibited in the outcrop of the Kimmswick limestone at Valmeyer. The outcrops in this portion of the bluff have not been studied in detail, and no collections have been made, but the observations which have been made indicate that the characteristics of the formation are not different here from other localities. Im- mediately south of the Valmeyer anticline, the Salem limestone is not clearly shown in the Mississippi river bluffs. All the beds which are exposed where one would expect to find the Salem limestone seem to belong in the St. Louis formation ; the Salem is either covered with the talus at the foot of the bluff or the strata have been faulted in such a manner as to obscure the beds in question. This region has been examined only in a hasty manner and a few days detailed work will doubtless make the relations clear. Below Chalfin Bridge P. O. the Salem limestone again appears in the base of the bluffs, the summit of the formation rising to a height of 59 feet above the bottom lands in the northwest corner of section 7, a little over one-half mile southeast of the post office. At this point the following section was ‘Carefully measured. Feet. 9 Hard, blue or gray limestones, more or less variable in texture and variously bedded, having the typical characteristics of the St. Louis limestone. 213-231 feet 18 8 Limestone filled with large and small colonies of the coral Lith- ostrotion. 198-213 feet 15 7 Limestones in every way similar to those above the corraline bed. 151-198 feet 47 6 Limestone filled with fossil cephalopods of various genera (W237). 150-151 feet 1 5 Limestone beds similar to those higher up, passing into an exceed- ingly hard, dense blue limestone, just beneath the cephalopod layer. 86-150 feet 64 4 Hard, siliceous limestone having almost the appearance of a very hard sandstone. 85-86 feet 1 3 Beds variable in character, for the most part magnesian, earthy limestones, buff or brown in color, with bluish beds near the top. 59-85 feet 16 2 Light colored, grayish or yellowish limestones, having the features characteristic of the Salem limestone. Fossils common (W236). 30-59 feet 29 1 No exposures to the level of the bottom land. 0-30 feet .!.] 30 The Salem limestone is represented by bed No. 2 of this section, this being the upper portion of the formation. The higher beds are all St. Louis limestone. 96 YEAR BOOK FOR I907. [Bull. No. 8 One mile southeast of the last section, opposite the residence of Mr. William Maeys, the Salem-St. Louis contact is only 25 feet in eleva- tion above the river bottom, the section being as follows : 5 Thin bedded magnesian limestones. 84-94 feet 10 4 Chert band. 83-84 feet 1 3 Magnesian limestone, quarry ledge. 77-83 feet 6 2 Thin bedded magnesian limestones. 25-77 feet 52 1 Limestone having the characteristic features of the Salem exposed above, covered with talus below. 0-25 feet 25 From this point the summit of the Salem limestone rises gently and regularly for a distance of a little over three and one-fourth miles, to the ravine which intersects the bluff about one mile below the northwestern boundary of the Renault grant, just south of which the Salem-St. Louis contact occurs at an elevation of 66 feet above the river bottom. Just below this point the continuity of the forma- tion is interrupted by a fault and one-half mile to the southeast the contact is recognized at an elevation of 176 feet. Continuing along the bluffs, the beds rise gently at first and then more abruptly to an anticlinal axis which intersects the bluff opposite the village of Renault. Over the anticline the Salem limestone beds have been practically removed so that the contact between it and the St. Louis limestone has not been seen, but the base of the Salem, resting upon the subjacent Keokuk-Warsaw formation, may be seen at an ele- vation of 145 feet in the bluff just below the intersection of the road to Renault with the river road in the northeast quarter of Section i. Assuming the thickness of the Salem as 100 feet, which is as close as it can be estimated for Monroe county, the Salem-St. Lauis contact would be at an elevation of 245 feet. Continuing to the southeast the beds descend rapidly upon the southern limb of the anticline, the Salem- St. Louis contact having an elevation of 95 feet about one mile from Randolph county line, and 65 feet at a point about one-half mile below. Before reaching the Randolph county line, the formation has passed below the level of the river bottom and is not again exposed until the neighborhood of Grand Tower, in Jackson county, is reached. Throughout Monroe county wherever the formation occurs, the litho- logic expression of the Salem limestone is uniform and it can be easily recognized. It is furthermore characterized throughout by the char- acteristic Spergen Hill fauna. At some points certain beds of the lime- stone might be satisfactorily and profitably developed as building stone. The Iron Mountain Railroad, running the entire length of the county between the bluffs and the river would furnish good transporta- tion facilities. The locality where the formation seems to be most favorably situated for quarry purposes is about one mile above the Randolph county line in the point of the bluff west of the road which runs in a northerly direction to the village of Renault. At this point the rock occurs in more than usually heavy beds ; it is apparently uniform in texture and color, and resists the action of weathering. Furthermore, it is not covered at this point by heavy ledges of the superjacent St. Louis limestone and a large quarry might be opened with but a minimum amount of stripping. Careful tests would be Wellek.] THE SALEM LIMESTONE. 97 necessary to determine whether the rock at this point would be equal for purposes of construction, to the celebrated “Bedford stone” of Indiana, but the superficial examination of the locality would seem to indicate this to be the case. Jackson county — In the vicinity of Grand Tower, in Jackson county, three conspicuous hills rise abruptly above the broad alluvial plain which extends from the Mississippi to the Big Muddy river. The first and larg-est of thes^e hills is known as “Big Hill” or “Fountain Bluff.” This elevation is several miles in length, its southern extrem- ity being two miles north of the town ; the constituent rock strata are of. Chester age below, passing upward into the Mansfield sandstone and conglomerate of the Pennsylvanian. Just northwest of the town, along the river bank, is the long narrow ridge known as the “Devirs Back Bone,” which is entirely of Devonian rocks. Northeast of the town is the third elevation which is much broader and less abrupt than the “Back Bone;” at its southern extremity the rocks are of Devonian age, but at its northern end they are Mississippian limestones. In the extreme northern part of this hill a quarry known as the “City Quarry” has been opened in which the Salem and St. Louis limestones are ex- posed. The beds at this point dip to the northeast at an angle of about 24 degrees so that the lower strata are exposed in the southwestern part of the quarry. Certain of these low’er beds exhibit features which are highly characteristic of the Salem limestone elsewhere, with the typical Spergen Hill fauna represented by an abundance of both spec- ies and individuals. The dividing line between the Salem and the St. Louis is not so distinctly shown here as in Monroe county, but the lower beds in the quarry are none the less distinctly Salem limestone. Union county — The stratigraphy of the Mississippian formations in Union county was misinterpreted by Worthen because of his failure to recognize the extensive faulting of the strata which has taken place in the southern part of the State. In the east and west section passing through Jonesboro and Anna he recognized a succession of higher and higher beds passing from the Devonian black shale through the Mississippian series in regular succession, except that the St. Louis limestone was believed to follow immediately after the sup- posed Kinderhook shales, the limestone ^ along Swan creek, east of Anna, being considered as the upper beds of the St. Louis*. A reconnaissance survey of this part of the State by the writer has shown that the structural features are by no means so simple as Worthen’s interpretation would indicate. The succession of the beds is perfectly normal through ■ the Kinderhook, Burlington, Keokuk-Warsaw, Salem and St. Louis, but their relations have been obscured by faulting. A fault with a general north-south direction seems to pass along Swan creek with the upthrow on the east, so that the supposed upper St. Louis beds of Worthen appear to be the Salem limestone. The fauna of the limestone exposed in the old quarries along Swan creek is nearly the typical Spergeq Hill fauna, and this occurrence of the fauna in beds supposed to be upper St. Louis is perhaps one of the facts which led Worthen to combine the Salem and St. Louis limestones in one formation. The Surv.. 111., vol. 3. pp 41-44: also Econ. Geol. 111., vol. 1. pp. 48^1-487. -7 G S 98 YEAR BOOK FOR I907. [Bull. No. 8 fauna at this locality has some features, however, which suggest that it is a representative of the recurrent Spergen Hill fauna of the Ste. Genevieve limestone lying above the St. Louis. The true relations of the beds in this region can only be determined by more detailed study. In its lithologic character the supposed Salem limestone of Union county resembles the same formation elsewhere except that some of the beds are more cherty than is usually the case with the formation. The survey of the region has not yet been carried far enough to determine the extent of the formation in the county, and as yet it has only been observed along Swan creek, where it is represented by at least 100 feet of strata. Conclusion. The Salem limestone, as has been shown in the preceding pages, is widely distributed in Illinois, from Hancock to Union' counties, al- though the outcrops of the formation are not continuous at the surface through this entire area. Its lithologic characters are more or less uniform throughout the State and it can usually be differentiated from the superjacent St. Louis limestone without difficulty. The faunal characters of the formation are even more uniform than the physical, and are identical with the faunas of the typical expression of the forma- tion in Indiana.. These beds which appear at intervals along the western side of the Illinois coal field, are doubtless continuous beneath it across the entire width of the State and a part of Indiana, coming to the surface again near the eastern border of the coal field in the latter State. In Indiana the formation affords one of the most valuable building stones of America. In Illinois it is apparently not usually so well adapted for such purposes as in Indiana, either because of the physical characters of the rock itself or because of the overlying heavy beds of St. Louis limestone, but at certain localities in Monroe county extensive beds could probably be quarried which would prove to be the equal of the Indiana “Bedford stone” in all respects. Appendix. Preliminary lists of species in the Salem limestone faunules col- lected in Illinois. W. 56. Warsaw, Hancock County. (See p. 85.) Rhipidomella dubia Hall. Spirifer subaequalis Hall. Fenestella serratula Ulr. Fenestella multispinosa Ulr. Rhombopora sp. Cystodictya lineata Ulr. Worthenopora spinosa Ulr. W 92. Near Lock Haven, Madison County. (See p. 91.) Fistulipora sprrnenens^fi Rom. Rhipidomella dubia Hall Orthothetes minntus Cum. Productus Sp. Spirifer subaequalis Hall. Spirifer lateralis Hall. Sleminula trinuclea Hall. Wkller. ] THE SALEM LIMESTONE. 99 W 93. Near Lock Haven, Madison County. Endothyra haileyi Hall, Zaphrentis spergenensis Worthen. Zaphrentis sp. Talarocrinus simplex Shum. Stenopora sp. Fenestella serratula Ulr. Hemitrypa prouti Ulr. Hemitrypa heedei Cum.? Cystodictya lineata Ulr. W 94. Riehl,s Station, Fistulipora spergenensis Rom. Polypora simulairix Ulr.? Cystodictya lineata Ulr. Spirifer hifurcatus Hall. W 95. Riehl’s Station, Endothrya haileyi Hall. Zaphrentis spergenensis Worthen. Archaeocidaris sp. Pentremites conoideus Hall. Rhombopora bedfordensis Cum.? Cystodictya lineata Ulr. Worthenopora spatulata (Prout). Orthothetes minutus Cum. Productus biseriatus Hall. Pugnax grosvenori Hall. Dielasma formosa Hall. (See p. 91.) Worthenopora spatulata (Prout). Productus altonensis N. & P. Productus biseriatus Hall. Productus indianensis Hall. Camarophoria subuneata Hall. Dielasma formosa Hall. Spirifer bifur catus Hall. Spirifer subcar diiformis Hall. Madison County. (See p. 92.) Spirifer subaequalis Hall. Spirifer lateralis Hall. Reticularia pseudolineata Hall. Platyceras sp. Madison County. (See p. 92.) Dielasma turgida Hall. Spirifer bifurcatus Hall. Spirifer subaequalis Hall. Eumetria marcyi (Shum.) Seminula trinuclea Hall. Cliothyris hirsuta Hall. Nuclua shumardi Hall. Microdon oblongus Hall. Straparollus spergenensis Hall. Holopea proutana Hall. Cladodus sp. (See p. 92.) W 96. East of Riehl’s Station, Madison County, Moniiopora beecheri Brab. Pentremites conoideus Hall. Fistulipora spergenensis Rom. Fenestella tenax Ulr. Orthothetes minutus Cum. Rhipidomella dubia Hall. Spirifer bifurcatus Hall. Reticularia pseudolineata Hall. Cliothyris hirsuta Hall. W 97. East at Riehl’s Station, Madison County. (See p. 92.) Rhipidomella dubia Hall. Spirifer lateralis Hall. Productus sp. Seminula trinculea Hall. W 43. Hull’s Hollow, Madison County. (See p. 93.) Endothyra baileyi Hall. vaphrentis cassedayi E. & H. Enallophyllum grabaui Green. Pentremites koninckana Hall. Poteriocrinus sp. Talarocrinus simplex Shum. t:,pirorbis annulatus Hall. Fenestella tenax Ulr. Fenestella exigua Ulr. Hemitrypa proutana Ulr. Hemitrypa nodosa Ulr. Polypora simulatrix Ulr. Polypora varsoviensis (Prout). Olyptopora sp. Orthothetes minutus Cum. Rhipidomella dubia Hall. Productus altonensis N. & P. Productus biseriatus Hall. Rhynchonella wortheni Hall. Rhynchonella macra Hall. Pugnax grosvenori AidiW. Dielasma formosa Hall. Dielasma turgida Hall. Spirifer bifurcatus Hall. Spirifer subaequalis Hall. Spirifer subcar dif or mis Hall. ICX) YEAR BOOK FOR I907. [Bull. No. 8 Spirferina spinosa N. & P. Reticularia setigera Hall. Eumetria marcyi (.Shum.) tSeminula trinuclea Hall. Cliothyris hirsuta Hall. Nucula shumardana Hall. Conocar dium catastomum Hall. Conocardium meekanum Hall. Myalina sp. Aviculopecten sp. Ooniophora plicata Hall? Microdon subellipticus Hall. Microdon ohlongus Hall. Microdon ellipticus Whitf.? Cypricardinia indtanensis Hall. Dentalium sp. Lepteopsis levettei (White). W 44. Hull’s Hollow, Zaphrentis sp. Platycrinus huntsvilliae Troost. Fistulipora spergenensis Rom. Fenestella serratula Ulr.? Cystodictya lineata Ulr. Worthenopora spatulata (Prout., Orthothetes minutus Cum. Rhipidomella duHa Hall. Produccus altonensis N. & P. Productus biseriatus Hall. Camarophoria subcuneata Hall. Pugnax grosvenori Hall. Dielasma formosa Hall. W 45. Hull’s Hollow, Pentremites conoideus Hall. Productus biseriatus Hall. W 42. Hopp Hollow, Monilopora beecheri Grab. Fistulipora spergenensis Rom. Anisotrypa fistulosa Ulr.? Fenestella tenax Ulr. Fenestella serratula Ulr. Fenestella multispinosa Ulr. Hemitrypa proutana Ulr. Polypora simulatrix Ulr. Polypora varsoviensis Prout? Polypora internodata Cum. Polypora spininodata Ulr. Rhombopora bedfordensis Cum.? Cystodictya lineata Ulr. Proutella discoidea (Prout.) Worthenopora spatulata (Prout.) Orthothetes minutus Cum. Productus altonensis N. & P. Pleurotomaria humilis Hall. Pleurotomaria piasaensis Hall. Pleurotomaria meekana Hall. Pleurotomaria subglobosa Hall. Pleurotomaria (several sp.) Bellerophon sublaevis Hall. Straparollus spergenensis (Hall). Murchisonia vermicula (Hall). Cyclonema levenworthna Hall. Naticopsis carleyana Hall. Bulimorpha elongata Hall. Holopea proutana Hall. Platyceras acutirostris Hall. Orthoceras sp. Leper ditia carbonaria Hall. Phillipsia sp. Madison County. (See p. 93.) Dielasma turgida Hall. Spirifer bifurcatus Hall. Spirifer subaequalis Hall. Spirifer subcar diif or mis Hall. Reticularia setigera Hall. Eumetria marcyi (Shum.) Seminula trinuclea Hall. Cliothyris hirsuta Hall. Conocardium meekanum Hall. Bellerophon sublaevis Hall. Straparollus spergenensis Hall. Holopea proutana Hall. Platyceras circularis Rowley. Madison County. (See p. 92.) Reticularia pseudolineata Halt Madison County.. (See p. 93.) Productus biseriatus Hall. Productus indianensis Hall. Pugnax grosvenori Hall. Dielasma formosa Hall. Dielasma turgida Hall. Spirifer bifurcatus Hall. Spirifer subaequalis Hall. Spirifer subardiiformis Hall. Spiriferina sp. Reticularia pseudolineta Hall. Eumetria marcyi (Shum.) Seminula trinuclea Hall. Cliothyris hirsuta Hall. Straparollus spergenensis Hall. Griffithides sp. Phillipsia sp. Wkllek. ] THE SALEM LIMESTONE. lOl U 48. Near Columbia, Monroe County. Zaphrentis spinulosa E, & H. Zaphrentis sp. Amplexus sp. Monilopora beecheri Grab. Pentremites conoideus Hall. Tricoelocrinus obliquatus Room. Metablastus bipyramidatis Hall. Synbathocrinus swallovi Hall? Batocrinus irregularis Casseday. Dichocrinus oblongus W. & W. Talarocrinus simplex Shum. Archaeocidaris sp. Stenopora sp. Lioclema punctata (Hall). Fenestella tenax Ulr. Fenestella compressa Ulr. Fenestella regalis Ulr.? Polypora biseriata Ulr. Fenestralia st. ludovici Prout. Rhombopora bedfordensis Cum. Cystodictya lineata Ulr. U 56. Zaphrentis spergenensis Worthen. Pentremites conideus Hall. Talarocrinus simplex Shum. Stenopora sp. Fenestella tenax Ulr. Hemitrypa proutana Ulr. Rhombopora bedfordensis Cum. Cystodictya lineata Ulr. Cystodictya ocellata Ulr. W 236. Near Chalfin Bridge, Orthothetes minutus Cum. Rhipidomella dubia Hall. Productus altonensis N. & P. Pugnax grosvenori Hall. Spirifer bifurcatus Hall. (See p. 95.) Worthenopora spatulata (Prout.) W orthenopora spinosa Ulr. Orthothetes minutus Cum. Rhipidomella dubia Hall. Productus altonensis N. & P. Productus biseriatus Hall. Strophalosiaf sp. Pugnax grosvenori Hall. Dielasma turgida Hall. Spirifer bifurcatus Hall. Spirifer subaequalis Hall. Spirifer subcar diif or mis Hall. Spiriferina spinosa N. & P. Reticulari apseudolineata Hall. Eumetria marcyi (Shum.) Seminula trinuclea Hall. Cliothyris hirsuta Hall. Platyceras acutirostris Hall. Phillipsia sp. Fish teeth. (See p. 95.) Worthenopora spatulata (Prout.) Productus altonensis N. & P. Productus biseriatus Hall. Dielasma formosa Hall. Spirifer bifurcatus Hall. Spirifer subcar diif or mis Hall. Deltodus sp. Cladodus sp. Monroe County. (See p. 95.) Reticularia pseudolineata Hall. Eumetria marcyi (Shum.). Seminula trinuclea Hall. Allorisma sp. Deltodus sp. 1^2 Miles South of Columbia, Monroe County. W 235. Near Brownsburg, Monroe County. Orthothetes sp. Rhipidomella dubia Hall. W233. Mississippi River Bluff, Zaphrentis cassedayi E. & H. Fistulipora spergenensis Rom. Fenestella sp. Cystodictya sp. Orthothetes minutus Cum. Rhipidomella dubia Hall. Productus altonensis N. & P. Productus biseriatus Hall. Pugnax grosvenori Hall. Dielasma turgida Hall. Spirifer bifurcatus Hall. Spirifer subcardiiformis Hall. Seminula trinuclea Hall. Spirifer subcardiiformis Hall. Reticularia pseudolineata Hall. Eumetria marcyi (Shum.). Athris densa H. & C. Seminula trinuclea Hall. Macrodon sp. Aviculopecten sp. Bellerophon sublaevis Hall. Platyceras acutirostris Hall. Grifflthides sp. Opposite Renault Station, Monroe Co. 102 YEAR BOOK FOR I907. [Bull. No. 8 W 263. Abandoned Quarries, Swan Creek, East of Anna, Union County. Endothyra haileyi Hall. Zaphrentis spergenensis Worthen? Zaphrentis sp. Cystelasma rugosum Ulr.? Syringopora sp. Palaeacis cuneiformis E. & H. Pentremites koninckana Hall. Platycrinus huntsvillae Troost. Melonitesf (plates). Rhipidomella dubia Hall. Productus punctatus Martin. Productus cora D’Orb. Camarophoria wortheni Hall. Dielasma formosa Hall. Dielasma turgida Hall. Reticularia pseudolineata Hall. Eumetria marcyi (Shum.) Seminula trinuclea Hall. Cliothyris hirsuta Hall. Nucula shumardana Hall. Aviculopecten sp. GoniopTioraf plicata Hall. Dentalium sp. Eotrochus concavus (Hall.) Bellerophon sp. Bucanopsis textiles Hall. Straparollus spergenensis Hall. Strophostylus carleyana Hall. BulimorpJia bulimiformis Hall. Orthoceras epigrus Hall. GrifUthides sp. Psammodus sp. Gtenacanthus sp. W. 264. Outcrop by Roadside, jSwan Creek, a Little Less Than ^2 Mile North of Last Locality, Union County. Orthothetes sp. Productus cora D’Orb. Productus sp. Dielasma formosa Hall. Dielasma turgida Hall. Spirifer bifurcatus Hall, Eumetria marcyi (Shum.). Seminula trinuclea Hall. Cliothyris hirsuta Hall. Aviculopecten sp. Enchostoma sp. W. 265. Outcrop by Roadside, Swan Creek, a Little Less Than % Mile North of Last Locality, Union County. Pentremites konincki Hall. Orthothetes sp. Productus sp. Dielasma formosa Hall. Dielasma turgida Hall. Spirifer bifurcatus Hall. Eumetria marcyi (Shum.) Seminula trinuclea Hall. Cliothyris hirsuta Hall. Nucula shumardana Hall. Nucula sp. Goniophora? plicata Hall. Lepetopsis sp. Bembexia elegantula (Hall)? Porcellia sp. Strophostylus carleyana Hall. GrifUthides sp. LOWER PALEOZOIC STRATIGRAPHY OF SOUTH- WESTERN ILLINOIS * (By T. E. Savage.) Contents. Page Introduction 104 Earlier geological work 104 Composite section of the Pre-Mississippian 105 Ordovician 109 Galena-Trenton 109 Richmond-Maquoketa no Middle Silurian 110 Alexandrian 110 Silurian ■ • Ill Clinton Ill Devonian 112 Helderhergian 112 Oriskanian 113 Onondaga 113 Hamilton • • . . . 114 Upper Devonian 115 Conclusion 115 * Previously published in briefer form in the American Journal of Science, May, 1908 104 YEAR BOOK FOR I907. [Bor.L. No. 8 Introduction. The following paper is a preliminary statement concerning the pre- Mississippian formations that occur in the southwest portion of Illinois. A detailed report on the stratigraphy and paleontology of these ter- ranes in the above mentioned area is in preparation by the writer. The field work on which the report is based was done during the summer of 1907, under the auspices of the Illinois Geological Survey ; while the paleontological study was made at the Peabody Museum, Yale University, under the direction of Professor Charles Schuchert. To the latter the writer wishes to acknowledge his indebtedness for valu- able assistance in the study and interpretation of the faunas and the data that were collected. The pre-Mississippian beds in this portion of the State underlie the surficial materials over an area 150 miles in extent. They appear in the southwest corner of Jackson county in the Back Bone and Bake Oven ridge, at the south end of Walker ridge, and at Bald Rock and southward on the east side of Big Muddy river. In Union and Alex- ander counties they extend from the flood-plain of the Mississippi east- ward to a general line passing within about one mile west of the towns of Alto Pass, Mountain Glen, Jonesboro and Mill Creek, to a point nearly two and one-half miles southeast of Elco, whence the line sep- arating the Devonian from the younger formations trends toward the southwest past the Diswood postoffice, to near the middle of section 28, T. 15 S., R. 2 W. Eastward they are bordered by Mississippian beds, while along the southern edge sands and clays of Tertiary age lie upon the flanks of these older formations. Occasional patches of Tertiary gravels occur within the region under discussion. This small area is exceedingly interesting geologically because of the fact that some of the formations here represented do not appear further north anywhere in the Mississippi valley. The successive beds were deposited in a basin of the Interior or Mississippian sea which, during a great part of the time, was more or less separated from that in which the older strata in other portions of the State were laid down. Owing to its proximity to Ozarkia this basin was subjected to vertical movements and therefore to variable conditions of sedimentation, very different from those that prevailed during the same time over the more northern areas. Earlier Geological Work. In volume III of the Geological Survey of Illinois, Professor Wor- then published reports on the geology of Jackson, Union and Alexan- der counties in which he describes, in a general way, the stratigraphy of the region under discussion. In 1897 Dr. Weller* published a list of fossils collected at the Bake Oven, in Jackson county, with a discus- sion of the relations of these to the Middle Devonian faunas of other localities. ♦“WellerT Jour. Geol., vol. 5, pp. 625-635. 1897. Savage.] PALEOZOIC OF SOUTHWESTERN ILLINOIS. I05 No careful detailed study of the lower Paleozoic beds of this region as a whole has ever been attempted previous to the present work. This neglect was doubtless due, in part, to the small size of the area ; to the absence of the more important economic deposits ; and to the fact that the deformations and unconformities occuring in this region have made the geological relations of the beds obscure ; and that many of the formations present here cannot be correlated with those in other portions of the State. Composite Section of the Pre-Mississippian Strata Occurring in Southwestern Illinois. The general relations of the Lower Paleozoic formations in south- western Illinois may be represented in a generalized section as follows : S D (O o > H Q Correlations. Location of sections. Descriptions of horizons. O. P. L) © ^ 0) 0) ^ "ci o "eS "ci ^£3 0.0 ja ©cfl acCc/} IZ a o3 a I w 'S e 4 a c h 3 10c. Greenish-blue shale, fossils almost none — 29 ft. 10b. Black shale with few fossils, hut carrying numerous very small balls of iron pyrite from % to % inch in diameter — 21 ft. 10a Brown to black, siliceous shale or shaly limestone with Leiorhjmchus plohuli- formis and Reticularia laevis — 36% ft. 9c. 9b. 9a, : w Q (U •a 7e. Dark gray, impure limestone with thin chert bands near the top. Fossils numer- ous, Nucleocrinus verneuili, Rhynchonella gainesij Meristella harrisi, Spirifer acum- inatum, Stropheodonta patersoni, etc. — SVs ft. 7d. Dark gray, impure, fine-grained limestone. Ghonetes mucronatus abundant in a zone near the middle. Other fossils are fthip- idomella vanuxem, Spirifer qrieri, Stropheodonta patersoni, 8. perplana, and Phacops cristata — 11 ft. 7c. Heavy layers of light gray, subcrystalline limestone. Fossils abundant. Ooscinium crihriformis, Gentronella glansfagea, Spirifer duodenarius, 8. macrothyris and Odontocephalus aegeria present through- out — 38 ft. 7h. Alternating iayers of light gray, arenac- eous, subcrystalline limestone and coarse- grained sandstone, containing Gentron- ella glansfagea, Meristella near lenti- formis, Rhipidomella cf. musculosa, Spir- ifer duodenarius and 8. macrothyris — 15 y2 ft. S rSS . “OP'S “cwp >> 'I N _ _i-r cc a IZi 7a. Bed of more or less iron-stained sand- stone, in places soft and friable, at other points cemented by a deposit of iron or silica, containing Michelinia stylopora, Aulacophyllum sp., Gentronella glans- fagea, Spirifer duodenarius, 8. macro- thyris and Odontocephalus arenarius — 18 ft. New Scotland, about 158 feet. | Upper Oriskany— Clear Creek chert. Camden chert, 237 feet. S.WAGE. ] PALEOZOIC OF SOUTHWESTERN ILLINOIS. 107 Composite Section of the Pre- Mississipian Shata — Continued. Location Correlations. of sections. a : -(fu o . O CO r. cs o _ l-J a ,0 5 o o > cop 6e. 6d. 6c. Descriptions of horizons. Bed! of light gray chert in layers .3-9 Inch- es thick, Amphigenia curia, Chonostro- phia reversa, Eodevonaria melonica, Schuchertella pandora and Spirifer worthenanus abundant — 5% ft. Reddish-hrown, friable sandstone with Michelinia stylopora, zaphrentis sp., Amphigenia curia and Spirifer duodcnar- ius — 2 5-6 ft. Layers of light gray chert, 4-8 inches thick. Anoplia nucleaia, Chonosirophia reversa, Eodevonaria melonica, Schucher- iella pandora and Spirifer worihennnus — IVa ft. a .2 c c o ‘S a o c ^ eo w P5 03 6b. 6a. ^ cfi ^ . a;> cc ^ ^ ^ II, ^ . a c G 'Z z 'Z Reddish-brown, friable sandstone — 2 ft. Bed of light colored chert layers, in qlaces alternating with impure siliceous lime- stone, and at other points composed wholly of chert bands. Fossils most abundant in the upper part. Amphi- genia curias, Anoploiheca flahelliies, Ea- ionia peculia/ris, Eodevona/ria melonica, Chonosirophia reversa, Schuchertella pandora, Spirifer xvorihenanus, and S. hemicyclus common in the upper part —225 ft. (In the southern part of Union county the lower chert layers are massive and contain but few fossils. In the pit worked by the M. & O. railroad, 1% miles north of Tamms, in Alexander county, may be seen an exposure of more that 100 feet in which few fossils were found.) A break in sedimentation. 5b. Heavy bedded, light colored, coarsely crys- talline limestone, with Eaionia singu- laris, Spirifer macropleura, S. perlameU losus, Siropheodonia heckii, and Stroph- onella punciuUfera — about 58 ft. Layers of impre, shaly limestone alternat- ing with bands and nodules of chert ; in the upper portion occur Dalmanella suhcarinaia, Merisiella laevis, Spirifer cyclopierus, S. perla/tnellosus and Sirop- honella punciuUfera — 100 ft. (The horizon of 5a appears to belong immediately below 5b. It is present at Bald Rock, and in the river bluffs further south, but the fossils were not so abundant at the later points.) lo8 YEAR BOOK FOR I907. [Bull. No. 8 Composite Section of the Pre-Mississippian Strata — Continued. c Location c . 03 A break in Deposition. g a . ob CO ■d s ,d o sa . . a A o a ® fl s" s ^ . fl - 0 H % . <% 030 HO Is la. Light gray, coarsely crystalline limestone^ in regular layers 3-48 inches thick ; the upper part characterized hy the fossils Receptaculites oweni, Eeberteila near occidentalis, Platpstrophia bifnrata, Plectorthis plicatella, Cytolites ornatu» and Platymetoous cucullus ; while the lower portion is marked by Receptacul- ites oweni, Rhynchotrema inaequivalve, Parastrophia hemiplicaa and Triplecia sp.— 68-80 ft. Ordovician. Galena-Trenton — A thickness of 68 to 8o feet of this formation is exposed in Alexander county. It appears at two points adjacent to the Mississippi river where the waters of that stream have cut across low arches which bring the Galena limestone above the level of the water. One of these exposures is a short distance below Thebes, where a thick- ness of about 68 feet of the limestone may be studied. The second fold crosses the river about two miles north of Thebes, a short distance west of the village of Gale, where the limestones may again be seen on Little Rock Island. The Galena formation is here a light colored, crystalline, non-mag- nesian limestone, in layers from a few inches to four feet in thickness, which is imperfectly exposed in the upper part. The lowest layers contain in abundance, Receptaculites oweni, Hpbertella near occiden- talis, Parastrophia hemiplicata, Platystrophia biforata, Rafinesquina alternata, Rhynchotrema inaequivalve, Strophomena emaciata, Trip- lecia n. sp., and the trilobites Bronteus lunatus, Bumastus trentonensis, Illaenus americanus, Isotelus maximus, 'and Platymetopus cucullus. Eighteen feet above low water Crania trentonensis, Cyrtolites ornatus, Plectorthis plicatella and Remopleurites striatulus are assosiated with most of the above mentioned forms. In the middle and upper parts the white color is in places mottled with pink, and the fossils become much less abundant. Receptaculites oweni is still common while Crania trentonensis, Hebertella near occidentalis, Platystrophia biforata, Rafinesquina alternata, Rhynchotrema inaequivalve and Triplecia n. sp. persist in diminished numbers. This facies of the Galena resembles, in its fossils and lithology, the, Kimmswick limestone of Ulrich, also described by Weller from Jersey and Calhoun counties.* The basin in which it was deposited was probably somewhat separated from that which received the sediments of the more northern dolomite phase of the Galena. ♦Weller: Illinois State Geol Surv., Bull. No. ' 4 . p. 222. no YEAR BOOK FOR 1 90/. [Bull. No. 8 Richmond-M aquoketa — The beds that belong to the Richmond for- mation have an aggregate thickness of 91 feet. This formation suc- ceeded that of the Galena after a long landi interval. All of the Utica and I.orraine deposits are wanting, and seemingly much of the Rich- mond is also absent. The formation in southwest Illinois consists of two members, 2a and 2b of the general section. The lower one (2a) is a sandstone or sandy shale — “Thebes sandstone and shale” — which is exposed along the flanks of the Thebes and Gale anticlines, and in the intervening trough. The materials are reddish brown where weath- ered, and blue where not changed by the atmosphere. The lower part is a sandstone, thick bedded and in regular Jayers, which is well ex- posed at the east end of the railroad bridge at Thebes. In the upper half the layers are thinner and, where much weathered, appear de- cidedly argillaceous. This more shaly horizon is well exposed in the river bank three-fourths of a mile south of Gale. Lingula cf. coving- tonensis occurs sparingly throughout the sandy shale of this member. The upper member is a bed of fossiliferous, bluish shale (2b of the section.) It is exposed in the bank of the river and in a cut along the Illinois Central railway about three-fourths of a mile south of Gale, where it overlies the “Thebes sandstone and shale” member. The bed has a thickness of 18 ft., and contains Cyclocystoides n. sp., Phylloporina near granistriata, Dalmanella testudinaria, Plectambonites sericea, Rhynchotrema inaequivalve? , Strophomena stdcataf, ::ygospira recuru- irostra, Conradella near dmhriata, and species of Isofelus resembling /. susae and /. platycephcilus. The. lithologic and faunal change from the Thebes sandstone member to this blue shale is abrupt, which may indicate a break between the two beds. The fauna reminds one much of the Black river formation, but as it occurs above the Rhynchotrema cap ax zones in Missouri, and its life assemblage is not at all that of the overlying Cape Girardeau limestone, it must belong in the Richmond with the Thebes sandstone. Neither of these members contain Rhynchotrema capax, the widely distributed guide fossil to the Richmond. However, across the river, in the vicinity of Cape Girardeau, Mo., were found thin layers of gray, sub-crystalline limestone, 5-7 feet thick, which contain Rhynchotrema capax and other Richmond 'fossils in abundance. This zone occurrs just above the white, heavy-bedded Galena limestone, and immediately below the Thebes sandstone. The same limestone horizon, bearing R. capax, is doubtless present in Ilinois, but the contact between the Galena and the Richmond formations was nowhere found exposed. The above shales and sandstone do not extend so far north as does the underlaying limestone. The sea in which they were deposited prob- ably washed the shores of the O'zarkian land area a few miles to the west which, during late Richmond time, was the source of the sedi- ments that make up these terrigenous beds. Middle Silurian. Alexandrian — The beds referred to this formation are exposed in Alexander county to a thickness of 44 feet. They include the Cape Girardeau limestone and the overlying beds containing Dalmanites danae and Whitheldella hillingsana. The Cape Girardeau limestone is well Savage. ] PALEOZOIC OF SOUTHWESTERN ILLINOIS. Ill exposed about two miles south of Thebes, in the bank of the river and along the streams in that immediate vicinity. It is also seen in a cut along the Illinois Central railroad and in the river’s bank one and 'one- half miles north of Thebes. In the former locality this member is near- ly 40 feet thick, and consists of black, fine grained, brittle limestone, in thin layers which are often separated by narrow partings of dark, calcareous shale. This zone has a rich fauna that appears abruptly at this horizon. Among the forms are several species of crinoids, Dal- manella near elegantula, Homoeospira n. sp., Leptaena rhomhoidalis, Raiinesquina mesacosta, Rhynchotreta n. sp., Schuchertella missourien- sis, Zygospira n. sp., Cormilites tenuistriata, C. incurvus, Platyostoma near niagarensis, Strophostylus sp., Acidaspis halli, Calymene sp., Cyphaspis girardeauensis and Encrinurus sp. At the exposure north of Thebes the Cape Girardeau limestone rests directly upon the fossiliferous blue shale (2b of section). This mem- ber is succeeded by a bed of dark gray limestone, oolitic in the upper part, which contains Favosites sp., Stromatopora sp., Atrypa rugosa, Clorinda n. sp., Homoeospira n. sp., cf Hindeila umhonata, Leptaena rhomboidalis, Platystrophia biforata, Raiinesquina mesacosta, Rhy- nchotreta n. sp., Schuchertella subplanus, (probably a coarse form of ♦S', missouriensis) Strophomena sp., Whitheldella billingsana, Dalman- ites danae, Dalmanites sp., and Lichas breviceps clintonensis. There are here no diagnostic fossils of the Richmond. The genera Favosites, Stromatopora, Atrypa, Whitdeldella, Homoeospira, Schu- ehertella and Clorinda do not occur in American Ordovician strata, while Atrypa rugosa and Lichas breviceps clintonensis are found in the Silurian. On the other hand the fauna is not directly related to that of the Clinton, from which formation it is separated by a marked , erosional unconformity. Schuchert cites* a fauna from Edgewood in eastern Missouri, collected by Ulrich, which corresponds closely with the above. Since there seems to be no direct time equivalent of these beds in the Ordovician or in the Silurian, as generally defined, the hori- zons 3a to 3c are classed as Middle Silurian strata that more or less completely bridge the lost interval between the Cincinnation and the Clinton. For these beds the time term Alexandrian is proposed, from Alexander county, Illinois, where they are well exposed; the term to have the same rank as Cincinnatian, which it immediately follows. Silurian. Clinton — The limestone of this formation has here a maximum thick- ness of 75 feet. One-half mile southeast of Gale it immediately overlies the shale member (2d of section) above the Thebes sandstone, all of the Alexandrian beds having been cut out by erosion prior to the deposition of the Clinton. One and one-half miles north of Thebes the Clinton limestone rests on the Whitdeldella billingsana zone (3c of section), while two miles south of Thebes it immediately over- lies the Cape Girardeau limestone (3a of section). The upper part of the Clinton (4c of section) consists of heavy bedded, pink or mottled ♦.Journal of Oeology. Vol. XIV, pp. 728-729.' 1906. 112 YEAR BOOK FOR I907. [Bull. No. 8 limestone, 23 feet thick, which contains many small, immature brach- iopods besides Plectambonites transversalis, RaHnesquina mesacosta, Spirifer near sulcata, Illaenus sp., and a few new species of Orthoceras. Below this pink limestone lie 6 feet of thin bedded, dark gray limestone with narrow bands of chert (4b of the section). The limestone layers contain Favosites favosus, Haly sites catenulatus, Stromatopora sp., A try pa rugosa, Orthis cf davidsoni, Orthis dabellites, Plectam- bonites transversalis, and var. elegantula, Stricklandinia triplesiana and Triplecia ortoni.. The above fauna corresponds with that of the In- terior or Western Clinton, as described by Foerste from the region of Dayton, Ohio. The lower portion of this formation (4a) is well exposed in the vicinity of Gale and two miles further north along Sexton creek, in the N. W. %. of sect. 27, T. 14 S., R. 3 West, where it consists of 46 feet of thin bedded, gray limestone, the layers of which are separated by narrow chert bands. The thickness of the Clinton is variable. It does not exceed 29 feet in the exposure south of Thebes, while near Gale, and along Sexton creek and in the river bluff two miles east of McClure, the aggregate thickness is 75 feet. Where the formation is thinnest it is the lower and not the upper layers that are absent. Devonian. Helderbergian — The rocks of Helderbergian age in Illinois corre- spond with the New Scotland formation of New York. They succeed the Clinton after an exceedingly long land interval represented by all of the Silurian after the Clinton, and the Coeymans of the Lower Devonian. In New Scotland time the Interior or Mississippian sea was much more restricted than during the Clinton. It extended as an embayment from the gulf region as far north as Jackson county, Illi- nois. It spread west to Oklahoma and east as far as southeast Tennessee. It was separated by a land barrier from the Atlantic embayment ( Cumberland basin) which occupied parts of New York, Maryland and northeastern Tennessee; and it is probable that the Kankakee barrier, as defined by Schuchert, prevented its spreading far to the north and northwest. The New Scotland formation in Union and Jackson counties has an aggregate thickness of more than 160 feet. The lower portion, for a thickness of 100 feet, consists of shaly limestone with interbedded bands of chert. This phase is exposed in the lower part of Bald Rock, four miles southeast of Grand Tower on the Big Muddy river. It appears in the east bluflf of the Mississippi river for some distance south from this point. It makes up Tower Rock, in the Mississippi river channel, west of Grand Tower, and it is exposed on the Missouri side of the river, in the quarry and in the cut made by the Frisco railroad company, a short distance south and west of this rock. At the latter point were collected Streptelasma recta, Dalmanella sub- carinata, Leptaena rhomboidalis, Leptaenisca adnascens, Meristella laevis, Spirifer cyclopterus, S. peramellosus, Stropheodonta punctuli- fera, Hausmannia sp. and Phacops logani var. Savage.] PALEOZOIC OF SOUTHWESTERN ILLINOIS. II3 The upper 58 feet of the New Scotland formation consists of light gray, heavy bedded, coarsely crystalline limestone. This facies is exposed in the south end of the Back Bone ridge where a fault brings it above the level of the flood plain. It forms the upper part of Bald Rock where another fault has raised it to the level of the adjacent Chester limestone, of Mississippian age. It occurs in the east bank of Clear creek in sections 23 and 24, T. ii S., R. 3 West. The beds furnished Aspidocrinus scutellaeformis, Anoplotheca concava, Eatonia singularis, Leptaenisca concava, Megalanteris condoni, Meristella arcu- ataf, Oriskania smuata n. var., Spirifer concinnus, S. cyclopterus, S. macropleura, S. perlamellosus, Stropheodonta beckii, S. varistriata, and var. arata, Strophoella punctulifera, Uncinulus nobilisf and U. nucleolata. Oriskanian (Clear Creek cherts, Camden cherts) — The Clear Creek formation consists of light gray to yellowish colored cherts that are usually in thin layers but which in the lower part are sometimes three to five feet in thickness. At some points the cherts are thoroughly leached and decomposed, and occur as a fine white powder that can be dug with a shovel, and is utilized for commercial purposes. This formation rests with erosional unconformity upon the New Scotland beds at the south end of the Back Bone ridge. Its fauna corresponds with that of the Camden cherts in western Ten- nessee. The beds represent deposits of the Upper Oriskany time, as is indicated by the interwedging of the upper chert layers with those of the basal portion of the succeeding Onondaga (see 6a to 6e of section). The chert formation has a thickness in Illinois of about 237 feet. Fossils are somewhat rare in the lower portion but in the middle, and especially in the upper, part there is a rich fauna, including Michelinia n. sp., Ambocoelia cf. umbonata, Amphigenia curia, Anoplia nucleata, Anoplotheca dabellites, A. hmbriata, Cen- tronella glansfagea, Chonostrophia reversa, Cyrtina hamiltonensis, Eatonia peculiaris, E. cf. whitheldi, Eodevonaria melonica, Stropheo- donta per plana, Megalanteris condoni, Oriskania sinuata, n. var., Pholidops terminalis, Rhipidomella musculosa, Spirifer worthenanus, S. duodenarius, S. macrothyris, S. hemicyclus, S. tribulis, S. cf. mur- chisoni, Schuchertella pandora, Acidaspis tuberculata, Odontocephalus arenarius and Phacops cristata. These upper Oriskany beds were deposited near the north end of the Mississippian embayment which at this time was even more con- tracted than during the Helderbergian. The basin was remote from, and not connected with, the NewYork-Maryland province (Cumber- land basin). It covered western Kentucky and Tennessee, and lapped over the southeast corner of Missouri and the east side of Arkansas, spreading an arm across northern Alabama. Onondaga — The sedimentation of the Upper Oriskany time con- tinued without a break into the Onondaga or Corniferous. The latter period was initiated by disturbances to the westward, in Ozarkia, which increased mechanical sedimentation in the Illinois area. These resulted for a time in the deposition, along the eastern shore of Ozarkia, of layers of sand containing Onondaga fossils alternating — 8 G S YEAR BOOK FOR I907. [Bull. No. 8 II4 with the return of the Oriskanian limestone conditions. Eventually sand deposition prevailed and there was spread over the region the basal sandstone of the Onondaga formation (ya of section), contain- ing Michelinia stylopora, Aulacophylluni sp., Amphigenia curta, Cen- tronclla glansfagea, Meristclla near lentiformis, Rhipidomella muscu- losa, Spirifer duo denarius, S. macrothyris , Conocardium cuneus and Odontocephalus arenarius. Early in Onondaga time an elevation in the southern portion of Union and in Alexander county put a stop to further deposition in that locality, while farther north, in Jackson county, sedimentation was uninterrupted. At the cut through the Back Bone and at the Bake Oven, a short distance north of Grand Tower, there is exposed a continuous section of the Onondaga formation showing a thickness of 115 feet. The beds consist largely of light colored, regularly bedded, more or less crystalline limestone which becomes arenaceous in the lower part. Fossils are abundant throughout the section. The upper layers are marked by Chonetes konickanus, Leptaena rhomboidalis, Pentamerella arata, P. papilionensis, Meristella rostrata, Rhynchonella gainesi, Spirifer acuminatus, S. grieri, S. macra, Stro- pheodonta patersoni, Conocardium trigonale and Onychodus sigmoides. In the lower part Nucleocrinus verneuili, Coscinium cribriformis, Cen- tronella glansfagea, Leptaena rhomboidalis, Meristella barrki, Pen- tamerella arata, Spirifer acuminatus , S. duodenarius, S. macrothyris, Stropheodonta patersoni, Dalmanites calypso, Odontocephalus aegcria and Onychodus sigmoides are common. During the Onondaga and the succeeding Hamilton time the warm waters from the gulf region, with their successive faunas, spread towards the northeast across Illinois and Indiana, passing around the north end of the Cincinnati axis, and mingled with those of the eastern embayment in western New York. Such water connections permitted free migrations within this sea, and explains the close corre- spondence between the various Middle Devonian faunas of south- western Illinois and those of western Ontario and New York. Hamilton — Throughout Hamilton time the Kankakee barrier or peninsula, extending from Ozarkia towards the northeast across Illi- nois, was largely effective in preventing the waters of the Interior or Mississippian sea from uniting with those of the Northwestern or Dakotan basin towards the northwest. As a result of this separa- tion the deposits and the faunas of Hamilton time, in Illinois, belong to two distinct provinces. The phase of the Hamilton in the vicinity of Rock Island, and in Jersey and Calhoun counties, belongs to the Northwestern or Dakotan province ; while that of the southwest Illi- nois belongs to the New York province. The New York faunal phase of the Hamilton is well developed in the south part of Union county, in the north half of sect. 34, T. 13 S., R. 2 West, and further north in the N. E. of sect. 34, T. ii S., R. 2 West. The formation is also represented by the upper beds near the north end of Back Bone ridge, in Jackson county. Savage.] PALEOZOIC OF SOUTHWESTERN ILLINOIS. II5 At the first mentioned exposure there is at the base of the Hamilton 28 feet of yellowish-blue shale which contains Leiorhynchus limitare, both the character of the sediment and the fossils reminding decidedly of the Marcellus shale of New York. This shale rests unconformably (erosional) upon the basal sandstone member (7a) of the Onondaga. It is succeeded by a few feet of limestone which, in places, is much leached and very fossiliferous. Athyris spirifer aides, Delthyris sculp- tilis, Rhipidomella penelope, Spirifer granulosus and Stropheodonta concava being very common. At points further north the lower beds of the Hamilton consist of dark colored, impure limestone which succeeds the Onondaga without any apparent break. The characteris- tic fossils of these layers are Microcyclus discus, Athyris vittata, Eunella attenuata, Spirifer fornacula, Cano car dium cuneus and Ony- chodus sigmoides. The middle portion of the Hamilton limestone is dark colored and evenly bedded, and contains Ambocoelia umhonata, Chonetes yandel- lanus, C. pusillus, Cranaena romingeri, Parazyga hirsuta, Pholidops ohlata and Spirefer pennatus. Above this horizon occurs about 25 feet of yellowish-brown, impure siliceous limestone with few fossils. Near the top of the formation occurs a few feet of hard, gray limestone containing Chonetes coronatus, Rhipidomella vanuxemi, Spirifer audac- ulus, S. pennatus, Tropidoleptus carinatus and Vitulina pustulosa. Upper Devonian — During Upper Devonian time the Mississippian sea continued to expand, spreading the materials of this formation more widely than those of the preceding. In the N. E. % of section 34, T. II S., R. 2 West, the lower deposits of the Upper Devonian are comfortable upon the Hamilton. There is here exposed a thick- ness of 33 feet of yellowish-brown (black where unweathered), silice- ous, shaly limestone, cherty near the top, and marked by Leiorhynchus globuliformis, L. mesacostalis, Reticularia laevis and Spirifer pennatus. At other points this cherty phase is succeeded by 50 or more feet of greenish to black, almost barren shales. These siliceous and dark colored shales are probably the equivalent of the calico rock, a mottled and leached, siliceous shale, present further south in Union and Alex- ander counties. They doubtless correspond with the Chattanooga black shale, Ohio black shale. New Albany black shale, and the Lower Portage beds of other states. Conclusion. The present studies have shown that the pre-Mississippian beds have a much wider distribution in southwestern Illinois than was formerly supposed. They have distinguished the presence of a bed of blue, fossiliferous shale (2b of section) containing the Cyclo- cystoides and Phylloporina fauna, immediately overlying the Thebes sandstone and shale horizon. They have demonstrated the presence, in this region, of Silurian beds corresponding with the Clinton forma- tion in Ohio. They have shown that the massive, crystalline lime- stone underlying the Clear Creek cherts in Jackson and Union coun- ties, belongs to the New Scotland formation of the Helderbergian. They have demonstrated the Upper Oriskany age of the Clear Creek YEAR BOOK FOR I907. [BuLU No, 8 I16 . cherts. They have disclosed the absence of the greater portion of the Onondaga formation in Alxander county and in the southern portion of Union; and they have shown that the Hamilton forrnation, in Union county, continues upward without a break into the Lower Port- age beds of the Upper Devonian. NOTES ON THE SHOAL CREEK LIMESTONE. (By JON’XrUDDEN.) Contents '• Paqb Introduction 1181 Earlier investigations 118 Known distribution 120 Description of exposures 120 Macoupin county 120 Madison county 122 Bond county 1 122 Clinton county 122 Washington county •• 125 Summary 125 ii8 YEAR BOOK FOR I907. [BuTjL. No. 8 Introduction. A fundamental problem in the investigation of the coal fields of Illinois is the correct correlation of the productive veins. Sixteen different coal seams were recognized by the old geological survey, and were grouped in two divisions, the “Upper” coal measures, includ- ing the thiu and unproductive coals, and the “Lower” coal measures, containing the thick and productive seams. A limestone formation supposed to be more or less continuous throughout the coal measure area of the State, and commonly called Carlinville or Shoal Creek limestone, was believed to mark the plane separating these two divis- ions. During the past season, several weeks were devoted by the writer to an attempt to trace the outcrops of this limestone in the southwest part of the State. Earlier Investigations. This limestone formation has been known under various names. In Illinois, Indiana and Kentucky, no less than six different local names have been applied to limestones, all of which are probably to be referred to this one horizon. The names Curlew, Shoal Creek, Carthage (?), Carlinville, New Haven and Somerville limestones are all believed to be synonomous for localities described in this State. Observations have not yet been carried far enough to make this quite certain. The earliest observations on the limestone under consideration were made by Owen, in Kentucky. The Carthage limestone was noted in Union county, Kentucky, “one mile below Uniontown.”* Its strati- graphic position in the Kentucky section f is between the Kentucky coals numbers 17 and 18. It is described as having a thickness of seven feet. The Kentucky and Indiana coal fields were studied earlier than the Illinois field, and attempts were made in these early reports to correlate all of the coal horizons with those of the Pennsylvania fields, whose sections were better known. The first attempt at correlation of this kind was made by Owen in his report on the Kentucky coal measures,! where the relation of the Curlew sandstone and limestone ♦Kentucky Geol. Surv., vol. 1, p. 60, 1856. tKentucky Geol. Surv., vol. 3, p. 18. 1857. iKentucky Geol. Surv., vol. 3, pp. 13-23, 1857; vol. 4, p. 387, 1867. Udden.J SHOAL CREEK LIMESTONE. 1 19 was shown graphically, the limestone occurring beneath a heavy ledge of sandstone and above a thick conglomerate, the Curlew sandstone being considered the equivalent of the Mahoning sandstone of Penn- sylvania. ^ Lesquereux in his Report on the Distribution of Geological Strata in the Coal Measures of Indiana* discusses the possible occurrence of the Curlew limestone in a section at Rockport, Spencer county, Indiana. It is doubtful, however, if the limestone in this section is the equiva- lent of the Curlew limestone of Kentucky, since no thickness equivalent to that given in the section has ever been noted at other nearby localities. I In Illinois the earlier investigators aimed to correlate the sections of the coal measures with the Kentucky and Indiana sections. Lesquereux I was no doubt the first one to record the extensive development of this ' limestone formation in Illinois, the Curlew limestone being noted in a I section at Shawneetown in his report on the coal fields of Illinois. He regarded this bed at Shawneetown as identical with the limestone I in a section near Hollaway, in Henderson county, in Kentucky. In I the same report the author mentions the following localities where I the Curlew limestone was observed, ‘‘on the Kaskaskia river, two I miles south of the town of Carlyle” and “at Jolofifs old mill site, ten I miles south of Carlyle.” f In Macoupin county the Curlew limestone was observed in the vincinity of Carlinville.J; There seems to be an error on the part of Lesquereux in the correla- tion of this limestone. In Kentucky his so-called Curlew limestone is not identical with Owen’s Carthage limestone. The Carthage lime- stone occurs some 940 feet higher up in the “Connected Section of Upper and Lower Coal Measures of Kentucky.”§ In Macoupin and Clinton counties, Illinois, the Curlew limestone is the equivalent of the Carthage limestone. In his report on the Geology of Washington, Clinton and Jefferson counties, II Englemann characterizes quite fully the limestone as it is developed in these counties and calls it the Shoal Creek limestone, apparently because of its excellent exposures along this creek in Clinton county. In describing the Geology of Gallatin county,^! Cox identified limestone near New Haven with “Owens Carthage limestone,” and in a report on the Geology of Bond county,** Broadhead identified the limestone occurring along Locust Fork creek as the Shoal Creek limestone. In a detailed generalized section of the coal measures of Illinoistt constructed by Worthen, the Shoal creek limestone was placed between coals number 9 and 'io. Both the lithological and paleontological characters were briefly described and typical localities at which the formation is best exposed enumerated. In LaSalle county the same author referred a limestone, number 3 in his section, of the river bluff in the neighborhood of Peru, to the Carlinville limestone. ♦Indiana Geol Reconn. Report 1859-60, p. 310, 1862. till. Geol. Surv., vol. 1, p. 222, 1866. mi. Geol. Surv., vol. 1, p. 227, 1866. ^Kentucky Geol. Surv, vol. 3, pp. 18-23, 1857. mil. Geol. Surv., vol. 3. pp. 148, 159-164, 175, 220; 1868. mil. Geol. Surv., vol. 6, p. 212, 1875. ♦♦Ill Geol. Surv.. vol. 6. pp. 129 alid 133, 1875. ttlll. Geol. Surv., vol. 6. p. 3, 1875. ttlll. Geol. Surv., vol. 7, pp. 47 and 48. 1863. 120 YEAR BOOK FOR I 907 . [Bull. No. 8 The name Somerville has been used more recently by Fuller and Clapp in the “Patoka Folio”* for a limestone which is probably the equivalent of the Shoal Creek limestone. Known Distribution. The most northern point at which a possible equivalent of the Shoal Creek limestone has been observed is at LaSalle. From this point its outcrops have been traced to the southeast, passing into Indiana a little north of the point where the Wabash river enters the State, and to the southwest, reaching their westernmost point at Carlinville in Macoupin county. From here they are found in a belt extending southeastward, reaching their most southern extension in Saline county. A few more localities are known in Gallatin and White counties. These are approximately the boundaries of the Shoal Creek lime- stone as mapped by the former survey. In the detailed mapping now in progress some minor deviations from this outline will no doubt be found. Within these boundaries the limestone when present lies at some distance below the surface, ranging from less than loo down to 700 feet. Exposures are limited to the bordering belt and are rarely met with, owing to the drift cover. Description of Exposures. The data collected in Macoupin, Madison, Bond, Clinton and Wash- ington counties, can best be presented in the form of a descriptive list of the localities where the rock was noted. (See map, plate 4.) Macoupin county — ^1. The most northern exposure observed is located on the Walker farm in Macoupin creek in the northeast quarter of section 35, T. 10 N., R. VII W., where the following section was noted: Feet. 3. A chocolate colored, coarse grained limestone, in beds, one half to six inches in thickness. This limestone has a fauna' abounding in Producti and Bellerophons. In examining the fossils the following were identified: Productus longispinus, Productus punctatus, Pro- ductus cora, Productus nehraskensis, Productus semireticulatus, Bellerophon mont fort anus, Bellerophon percarinatus, Bellerophon meekanus, Aviculopecten occidentale, Straparollus subquadrata, Chonetes variolata, Orthoceras rusTiense, Der'bya crassa, Spirifer cameratus, Lophophyllum proUferum, Seminula argentea, 8piri- ferina kentuckiensis, Myalina, sp. und., Murchisonia, st). und 3% 2. Grayish colored shales 10 1. A very hard, bluish gray limestone, occurring in seams varying from 3, 8 to 12 inches in thickness. On weathering the limestone turns brown, containing such fossils as Seminula argentea, Reticularia perplexa, Productus longispinus, Hustedia mormoni, Pugnax uta, Dielasma hoivedens, Amhocelia planoconvexa, Spirifer kentuck- iensis 2 2. Between three and a half and four miles west of the last locality, on Harrington creek in the northwest quarter of section 31, T. 9 N., R. VII W., the same limestone as number one of locality number one was observed. Its thickness is about 6 feet, and on fresh exposure has a bluish gray color, but *U. S. G. S. Geol. Atlas of the U. S.. Patoka Polio, No. 105, 1904. stale (teiolosical Survey,. Bulletin No. 8. Pl. 4. •Map sho\viiif>: distribution of Shoal Creek Limestone. Uddbn.] SHOAL CREEK LIMESTONE. I2I on weathering it turns brown. The beds vary in thickness from 6, 12 to 18 inches. Fossils are rather few in number and the most conspicuous form being a gasteropod, apparently a Naticopsis, which is associated with Spirifer cameratus, Reticularia perplexa. Seminula argenea, LopUopfiyllum pro- liferurriy and an undetermined pelycypod. 3. On the east side of Spanish Needles creek, in the southwest corner of the northwest quarter section 21, T 9 N., R. VII W., the following section was observed: Feet. 2. A bluish gray limestone very hard, in beds 9, 12 and 18 inches in thickness, breaking into very irregular splintery pieces. It weathers to brown J 1. Grayish shale with some bituminous partings 3-4 4. In a small tributary to Spanish Needles creek, in the northwest quarter of section 28, T. 9 N., R. VII W., limestone and shale was observed in the same relation as in locality number three. The Shoal Creek limestone can be traced along the greater part of Cahokia creek from its headwaters in section 36, T. 8 N., R. VII W., to section 25, T. 7 N., R. VII W. 5. Along the Cahokia creek east of Mount Glare, close to the center of section 36, T. 8 N., R. VII W., the following section appears: Feet. Inches 4. Dark gray colored limestone, in beds varying from 6 to 18 in- ches in thickness, on weathering turning brown. This lime- stone assumes a pebbly appearance on weathering, and this is due to the unequal hardness of the different parts of the rock. The following fossils were observed: Reticularia per- plexa, Spirit er cameratus, pugnax uta, Hustedia mormoni, Seminula argentea, Lophophyllum proliferum, Productus longispinus, and an undetermined gasteropod 6-7 3. Dark shale 1 2. Coaly seam 1 10 1. Dark colored shale 4 6. Further south along the same creek in the southeast quarter of section 12, T. 7 .^N., R. VII W., the same limestone was observed with a thickness approximately 7 feet. 7. In the northeast quarter of section 13, same township and range, along the same creek, limestone overlies a shale as below: ' Feet. 2. Grayish colored limestone, with an abundance of the corals Lopho- phyllum proliferum and Campophyllum torquium 5 1. Grayish colored shale 7 8. Another locality is on a small tributary to Cahokia creek in the north- east quarter of section 19; in the northwest quarter of section 20, and in the south half of section 17, T. 7 N., R. VI W. The thickness of the limestone is about 5% feet, dark gray in color, occurring in beds 6 and 12 inches in thickness. On weathering the limestone assumes a brown color. A few fossils were noted, especially a gasteropod, which has been observed fre- quently in other places besides Productus longispinus, Reticularia perplexa and Seminula argentea. 9. About one and a half mile west of Staunton, along the creek running north and south through the center of sections 24, 25 and 26, T. 7 N., R. VII N., limestone is fairly well exposed. In the southwest quarter of section 30, T. 7 N., R. VI W., a quarry has been worked in this limestone, and the follow- ing relations were observed: 122 YEAR BOOK FOR I907. [Bull. No. 8 Feet. 4. Worthen’s chocolate colored limestone. A very coarse-grained lime- stone, in places resembling a calcareous sandstone. It varies in color from yellow to brown. On weathering this rock has become very porous and readily disintegrates. It contains numerous fos- sils, such as different Producti and a number of Bellerophons. On account of the extensive weathering that the rock has suffered, the fossils are usually poorly preserved 3-4 3. Grayish blue shale without fossils 15 2. A bluish gray colored limestone, in seams varying in thickness from 9, 12, 18 and 24 inches. On weathering the limestone turns brown. 614 1. A grayish colored shale. A small seam about 3 inches in thickness immediately underneath the Shoal Creek limestone was very fossil- iferous, containing a great number of Ghonetes 4 Madison county — 10. The most conspicuous exposure of the Shoal Creek limestone observed in this county is to be found near the village of Saline, on A. J. Criaft’s place, in the northwest quarter of section 4, T. 4 N., R. V W., on Silver creek. The following section was noted in quarry operated by Mr. Craft: Feet. 4. Light colored shale calcareous 214 3. Dark gray limestone, rather fine-grained, tough and breaking into small irregular splinters. Containing fossils such as Seminula argentea, Pugnax uta, Productas longispinus, Spirifer cameratus and Naticopsis altonensis 414 2. A small seam of dark colored shale that contains a rather large num- ber of fossils, especially a Ghonetes, Derbya crassa and Productus longispinus 1 1. A black slate, very stiff and with a great number of joints, containing no fossils 214 11. In the creek near the south line of the southeast quarter of section 31, T. 3 N., R. V W., near by to the north the rock was formerly quarried. 12. A little to the west of the Buckeye school house in section 20, T. 3 N., R. V W. 13. In the bed of the main creek near the north line of the northeast quarter of section 19 the limestone is exposed for a distance of 10 rods or more. In a ravine joining this creek from the south in the northwest quarter of the same section it also appears in a face 6 feet high. 14. In the bed of 'the main creek, some rods northwest of the center of the northwest quarter of section 1, T. 3 N., R. VI W., were broken blocks somewhat disturbed. 15. About two miles north and one mile west of Highland the limestone is exposed in a creek. It here overlies a black carbonaceous slate. Bond county. — 16. East of the center of section 33, T. 4 N., R. IV W. undisturbed ledges of limestone overlie some black slate, under which is a two inch seam of impure coal. The ledges appear in the north bank of the main creek running from west to east through the section. Disturbed blocks of the limestone appear further up in the creek. 17. In the southwest corner of section 34, T. 4 N., R. IV W, the lower ledges of the limestone form the bed in the creek running north for a dis- tance of some 150 yards. The overlying sandy shales were seen in the wagon road to the south. Slabs of black slate in the rubble indicate other exposures further up the creek. In the bank of the creek near the bridge in the center of the southwest quarter of section 35, T. 4 N., R. VI W, the limestone shows in ledges of considerable thickness. Glinton county . — In the ravine running from west to east through the center of the south half of sections 2, T. 3 N., R. IV W, the limestone ap- pears in several places, the greatest thickness noted is four feet. About two feet of the underlying black stiff slate was also seen, but no coal. Uddbn.] SHOAL CREEK LIMESTONE. 123 19. The same rock occurs again in the ravine running east through the northeast quarter of section 11, T. 3 N., R. IV W. In the west bank of Shoal creek at the ford near the east quarter post of the section shreds of the limestone were seen under the drift and overlying some 24 feet of sandy bluish shales, which has several bands or layers with concretion of iron carbonate. These are mostly flattened bodies about two inches and four inches wide. 20. Near the center of the north half of section 14, T. 3 N., R. IV W, in the south bank of the creek which runs east, the following section was noted: Ft. In. 6. Limestone 2 5. Three layers of limestone measuring respectively 2, 3 and 4 inches in descending order 9 3. Seam of clay 1 2. Limestone 2 8 1. Limestone in slabs apparently slightly displaced 3 The ledges at this place have a notable dip to the east which was estimated at no less than two feet in one hundred. The lower three feet of the rock exhibits the habit noted elsewhere of developing parting seams at intervals of about three inches. The rock has been quarried in a ravine some sixteen rods to the northwest of this exposure. 21. Near the east line of section 23, T. 3 N., R. IV W, the limestone was noted in the south hank of Shoal creek, where this crosses the east line of the section about one-third of a mile north of the northeast corner of the section. It lies at an elevation of about ten feet above the bottom of the creek. 22. In the north half of the northeast quarter of section 27, T. 3 N., R. IV W., the bed of the creek running east exposes the limestone for a dis- tance of several rods. There is a thickness of about flve feet. The weather- ing has brought out the quite uniform three-inch layers in the ledges, es- pecially in the upper ones. The upper surfaces of these layers present a knotty appearance due to numerous irregular elevations of an inch or more, from six inches to a foot wide. 23. One-fourth of a mile north of the center of section 26, T. 3 N., R. IV W., two feet of limestone was again noted in the same creek as above. 24. In the north bank of the creek in the northeast corner of section 34, T. 3 N., R. IV W., the Timmerman quarry is located and this limestone has been quite extensively worked. The section is as follows: Ft. In. 6. Limestone in three ledges measuring respectively from above downward 8, 12 and 12 inches. The following fossils were noted: Aviculopecten occidentale, Seminula argentea and a Productus 2 8 5. Limestone in two ledges, upper 8 inches, lower 12 inches 1 8 4. Dark clay shale 4 3. Limestone 9 2. Stony or indurated shale with crystals of selenite 5 1. Bluish gray sandy limestone weathering brown disposed to ex- hibit on weathering bedding seams about two and one-half inches apart 4 3 25. Half a mile further south, in a ravine which joins this creek from the south, this rock has been quarried for a lime kiln. It is seen to overlie a black slate. This is in section 35 same township and range. 26. At the old mill site on the west bank of Shoal creek in the southeast quarter of section 11, T. 2 S., R. IV W., the following section was noted above the water during a rise in the creek: 124 YEAR BOOK FOR I907, [Bull. No. 8 1 I in. 7. Limestone in one strong ledge 2 6. Blue clay shale 3 5. Limestone 3 4. Blue shale 3 3. Limestone with alternating clayey layers 6 2. Blue clay shale 4 1. Limestone 2 0 Almost the entire outcrop shows seams from one-half to three inches apart. These always run in irregular curves up and down corresponding to in- equalities on the surface of the slabs into which much of the rock is broken. A syringoporoid coral was noted in profusion in a block in the masonry of the old dam. 27. Near the southwest corner of section 13, T. 2 N., R. IV W., several feet of the limestone are to he seen in the bed of the creek near the wagon bridge close to the Breese pumping station. 28. One-fifth of a mile west of the northeast corner of section 8, T. 2 N., R. V W., Knaus quarry is located. The section shown in the quarry is as below: Ft. In. 5. Marly soft shale or clay with many fossils . 6 4. Limestone in three subequal ledges separated by marly and fossil- iferous clay partings 2 3. Dark shale 6 2. Bluish gray compact limestone '. 5 8 1. Bluish gray shale 2 29. In the west bank of Sugar creek in the southeast quarter of section 34, T. 2 N., R. V W., large blocks of limestone were seen in several places, and a short distance to the west, limestone has been blasted out of a well under some forty feet of drift. 31. In the bed of the creek running east and west through the north half of the northeast quarter of section 27, T. 2 N., R. V W. 32. A quarry has been worked on a small scale in a ravine south of the B. & O. S.-W. railroad near the west line of section 22, T. 2 N., R. V W. 33. Quarries have been worked on both sides of the main creek near the center of section 21, T. 2N., R. V W. 34. Large loose blocks of the Shoal creek limestone lie in the bed of the creek a little east of the center of the south line of section 17, T. 3 N. R. IV W. 35. North of the wagon bridge over the main creek near the center of the northwest quarter of section 9, T. 2 N., R. V W., the rock was also noted. 36. Southwest of Qarlyle about two miles and a half, in the northeast (iuarter of section 35, on Stone Quarry creek, a quarry has been operated where the following section was observed: Ft. In. 4. A grayish colored limestone, weathering brown, in seams 3 and 12 inches in thickness, containing a great number of crinoid stems 3 4 3. Dark colored shale with crinoid stems and Der'bya crassa 6 12 2. Shoal creek limestone, gray color, very hard and breaking up into irregular splinters, in beds 6 and 18 inches thick, with a great abundance of Productus longispinus between bedding planes 6 7 1. A very black slate, to bottom of creek 3 In the northwest quarter of section 35 in the same township and range limestone similar to number 4 of locality 36 was observed. Fossils are more abundant and a great number of a Chonetes and a Productus were noted. The limestone is more sandy and a great number of imbedded fiakes of mica were observed. The total thickness amounted to about three feet. Uddbn.] SHOAL CREEK LIMESTONE. 125 37. In a ravine north of the cemetery north of Carlyle in section 18, T. 2 N., R. II W., a limestone similar to the above is observed with a thick- ness about four feet. The limestone is greatly weathered and showed the sandy appearance and contains flakes of mica. Fossils are rather abundant. Washington county. — About one mile north of Nashville along the west side of the creek in the northwest quarter of the section 13, T. 2 S., R. Ill W., limestone has been quarried. It is approximately four and a half feet in thickness, bluish gray in color, very hard and containing Reticularia per- plexa, Productus longispinus, Seminula argentea, and an undetermined gasteropod. Beneath the limestone, a grayish colored shale was observed about one foot in thickness containing many fossils such as a ChoneteSt Derbya crassa and Productus longispinus. 39. A similar limestone has been quarried about two miles west of Nash- ville in section 22, T. 2 S., R. Ill W. 40. Along Beaucoup creek quarries have been worked in the Shoal creek limestone. On Mr. Merkles’ place in the southwest quarter of section 34, T. 2 S., R. II W., the following section wjus noted: Ft. In. 1. Bluish gray colored limestone. Very hard, breaking into irregu- lar pieces and weathering brown. The following fossils were observed: Productus longispinus, Spirifer cameratus, Pugnax uta, Reticularia perplexa, Seminula argentea and an unde- termined gasteropod 4 5 2. A very black slate to bottom of creek 2 In digging a well at Mr. Wm. Merkles’ place it was observed that this slate had a thickness of four feet, below which a gray shale or “soapstone” some 25 feet in thickness is reported. 41. This same limestone was observed in the northeast quarter of section 34, T. 2 S., R. II W., and also lalong the creek crossing the east and west highway between section 23 and 26 same township and range. Summary. In the exposures that have been described, the following succession appears above and below the Shoal Creek limestone 5. Chocolate colored linaestone, 4 feet. 4. Gray shales, 15 feet. 3. Shoal creek limestone, 7 feet. 2. Gray shales, 4 feet. 1. Black slate, 6 inches to 4 feet. The topmost limestone (number 5) is coarse grained and brown in color. In some places it has the appearance of a sandstone, containing some quartz sand and flakes of mica. Fossils are numerous, but in most cases poorly preserved on account of its rapid disintegration on weathering. The grayish colored shales (number 4) vary in different localities in both color and texture. Occasionally they contain bituminous partings. No fossils have been observed in their upper portion, but a few have been noted in the shale resting on the Shoal Creek limestone. The Shoal Creek limestone (number 3) is generally bluish gray, com- pact, close textured, and very hard, breaking into irregular splintery pieces. On weathering it assumes a rusty color. It averages about seven feet in thickness. There are two features that are characteristic of this limestone, one a blotchy appearance, and another its tendency to weather into seams two and one-half or three inches in thickness. 126 YEAR BOOK FOR I907. [Bull. No. 8 It is interesting to note the relative abundance of the fossils in the Shoal Creek limestone. The fauna of this limestone excluding the shaly partings occurring between the different beds, is quite limited in forms. Only four fossils are abundant: Productus longispinus, Reti- cularia per pie xa, Seminula argentea and a gasteropod, probably Nati- copsis altonensis, usually found in the upper foot of this limestone in a poor state of preservation. Associated with these one occasionally finds Hustedia mormoni and Pugnax uta. On comparing the fauna of number 5 of the above section, with that of the Shoal Creek limestone, one is impressed with the difference between the two. There are present in the upper rock an abundance of Producti such as P. longispinus, P. punctatus, P. cora, P. nebras- kensis, P, semireticulatus, and Beller option Meekanus, and with these are a number of Chonetes variolata and Spirifer cameratus. The grayish colored shales (number 2) varies in thickness from one to four feet. Fossils have been found in the upper three or four inches which lie in contact with the limestone. There is usually found a great abundance of Chonetes mesoloba and Derbya crassa. The black slate (number i) is cut up by joints which are usually five or six inches apart, and breaks readily into thin pieces along the lamination planes. Another peculiarity of this slate is that it contains some grayish white traversions resembling fucoid markings. (Plate 5.) These run parallel with the bedding planes and are from an eighth to more than half an inch in breadth and run variously in straight and sinuous courses through the slate. Their forms suggest th^ these may be tracks of animals which inhabited the mud which formed the slate. There are a number of small stone quarries throughout this area, although none are worked on a large scale. No building stone is exported, and such quarries as these, merely supply the local demand for building stone and in one place for road material. state Geological Survey. Bull. No. 8, PI. 5. Fuccidal markings in black slate associated with the Shoal Creek limestone. i- X\ UNIVERSITY OF ILLINOIS- URBANA N30 11 2088464927 A