, J: ( I LI3RARY OF THE NiVERSITY of ILLINOIS. THE GLACIAL DEPOSITS OF INDIANA, BY FRANK LEVERETT, J OF THE U. S. Geological Survey. i i , . .. . , , WwtfjSbJL Tiik Inland Educator 23 fire.” Many a good flint is useless, because no friction is applied. i / We have recognized that poetry excites images by addressing i'self to the imagination and mem- pry, and therefore aids in psychic action, and it occupies its legitimate place. But the remaining .■wo-thhds of this circle of beauty, have been put aside as non-essential. Mr. Butterworth, well-known as the editor of die “ Youth's Companion ,” quoted recently and with much emphasis to a body of educators — “Learn, not how to get a living, but how to lire." When this idea becomes the prevalent one, and the fact that fifty cents per day will keep your physical self in good condition, while the entire material universe is not sufficient nurture for the mental body — it will then be recognized that those studies which teach “how lo live” will be as essential as are those which teach us “howto get a living.” Poetry, art, and music are all rec- ognized as avenues leading to larger realms, — as the “Jacob’s Ladder” by which a higher intellec- tual atmosphere is reached : but because of its more immediate connection with sensation, music, may be rightfully regarded as the more universal, the more powerful of the three. In poetry, painting, or sculpture, intervening act or acts, are necessary before the elements are appreciated by sensation, while in music, the sen- sations of tone are the material of the art. Because of this union, music deals more intimately with the emotions, than any other educational factor, and thus becomes an ethical force. Not only so, but the psychic processes which a well-directed lesson in music causes, exceed in number and power those caused bv almost any two recitations of any other branches; and, added to this, the study itself lifts these processes out of the “peda- gogical rut,” and wraps around them its own in- comparable beauty. Are not those who hold the affairs educational in their grasp — who hesitate to place these phases of education before the child, depriving him of a heritage that is priceless? And is not this legiti- mate part of every training eyed askance, mainly because of the burden of opposition which the un- knowing, unthinking public would cause the lead- ers of such a movement to bear? There is an ancient legend which would just here be apropos. It runs like this : — “ When birds were first formed they were created without wings. They lived this way for a long time, gathering their food and journeying in a slow troublesome way. Finally, as if this mode of life were not hard enough, God placed a little burden across their backs, and said, ‘I wish you to carry this for me.’ This they did also for a long time cheerfully and uncomplainingly, and because of the spirit with which the burden was borne — it was given to them forever, but changed — into wings.” If this burden (if it seems so) of placing before children suggestions of their better, higher nature be borne in the spirit of justice to the minds to be educated, it will be changed into wings for all. Bella Pakk. Franklin, Ind. Site Considered tite Ltey. At a Teachers’ Convention in Detroit, lately, a lady speaking about the influence of beautiful objects upon the character and conduct of young pupils, told a pretty story received by her from an eye-witness, and thus reported by the News Tribune. The occurrence took place in New York. “ Into a school made up chiefly of children from the slums the teacher one day carried a beautiful cal la lily. Of course the children gathered about the pure, waxy blossom in great delight. “One of them was a little girl, a waif of the streets, who had no care bestowed upon her, as was evinced by the dirty, ragged condition she was always in. Not only was her clothing dread- fully soiled, but her face and hands seemed totally unacquainted with soap and water. “As this little one drew near the lovely flower, she suddenly turned and ran away down the stairs and out of the building. In a few minutes she returned with her hands washed perfectly clean, and pushed her way up to the flower, where she stood and admired it with intense satisfaction. “It would seem,” continued Miss Coffin, “that when the child saw the lil v in its white purity, she suddenly realized that she was not lit to come into its atmosphere, and the little thing fled away to make herself suitable for such companionship. Did not this have an elevating, refining effect on the child? Let us gather all the beauty we can into the school-room .” — The Youth's Companion. No. Freedom has a thousand charms to show, That slaves, howe’er contented, never know. * * * «■ * * * « Religion, virtue, truth, wlmte’er we call A blessing — Freedom is the pledge of all. Cow per — Table Tall:. For murder, though it have no tongue, will speak With most miraculous organ. Sha KESI’E.UIE. — Hamlet. 24 The Inland Educator SCIENCE. Conducted by Charles Ii. Dryer. “ To read a statement of a fact (jives knowledge; to ver- ify the fact gives training ; to discover it gives inspira- tion. Training and inspiration, not the facts them- selves, are the justification of science teaching .” Studies in Indiana Geography.— IV. The Glacial Deposits of Indiana. By Frank Leverett of the r. S. Geological Survey. Note Concerning the Glacial Boundary. The glacial map of Indiana which is here presented, was prepared in March, 1896, and the position of the glacial boundary in Southeastern Indiana and adjacent portions of Kentucky, was based mainly upon a map prepared by Prof. G F. Wright, for his official report (U. S. Geol Survey, Bui. No. 58, 1890, p. 05). In the month of June, 1890, the writer examined the imme- diate borders of the Ohio valley from near Louisville up to Maysville, Kentucky, and found that the glaciation extended to the Ohio river throughout this distance, nearly 200 miles, except perhaps for a few miles below Maysville. In several places till was found in considerable amount south of the Ohio, not only in the bond of the Ohio opposite Cincinnati, where it had been noted by Prof. Wright and others, but also at numerous points both above and below this bend. The full extent of glaciation and the position of the glacial boun- dary in Northern Kentucky has not, however, been deter- mined, nor lias further study been given the boundary westward from Louisville. There seems to be a general agreement among the several geologists who have worked in Southern Indiana, that an unglaciated district extends from the Ohio river northward as far as Northern Monroe county, but the full extent of this unglaciated district has not been determined. The glacial boundary as laid down on this map should, therefore, be considered as, at best, only a rude approximation. introductory. In Indiana, the glacial deposits and scorings have been recognized from the earliest days of set- tlement; indeed, it is in this state that we find about the first recognition in America of the bowl- ders as erratics and of strife as products of ice action. So long ago as 1828, granite and other rocks of distant derivation were observed by geologists near New Harmony, in the southwestern part of the state.* At nearly as early a date (1842), strife were noted near Richmond, in the eastern part of the state, f Notwithstanding the early date at which obser- vations of glacial action began, very little attention was given to the drift, here or elsewhere, until within the past twenty years. It was commonly passed over in geological reports much as the soil *See Geology of Indiana, 1878, pp. 105-106. |See Araer. Jour. Sci., Vol. XL1V, 1842-3, pp. 281-313. is even to-day, with some casual remark concerning its presence in great or small amount. Within the past twenty years interest in these deposits, be- cause of the varied history which they reveal, has been so aroused, that many geologists, both in America and Europe are making a systematic study of them. In Indiana, these deposits are engaging the atten- tion of both the State and the United States Sur- vey. The study of general features and a com- parative study of the drift of Indiana and neigh- boring states has been undertaken by the United States Survey, while the detailed examination of deposits has been entered upon by the State Sur- vey. Professor T. C. Chamberlin lias superin- tended the United States Survey work and has him- self silent considerable time in Northern and West- ern Indiana. Under his direction Professor G. F. Wright and Professor J. C. Branner, have investi- gated the glacial boundary; Professor L. C. Woos- ter has studied the district north of the Kankakee, and t he writer has made a reconnoissance of nearly all the drift-covered part of the state. Professor Wright’s results have already been published in United States Geological Survey Bulletin, No. 58, issued in 1890. Professor Chamberlin’s earlier results are set forth in his paper on the Termi- nal Moraine, in the Third Annual Report of the United States Geological Survey for 1S81-82. The later results of his studies and those of Professors Branner, Wooster and the writer, are largely unpublished. Through the courtesy of Professor Chamberlin the writer is permitted to set forth some of the leading results in this paper. The work of the State Survey has not been uni- form. Portions of it have been less detailed than that of the United States Survey, while other por- tions have been carried into greater detail. Proba- bly the most detailed and careful study of any con- siderable area is that made by Dr. C. R. Drver in the northeastern part of the state.* An examina- tion of the reports of t he Indiana Geological Survey will serve to set forth these differences and to show the importance of extending the detailed study of glacial deposits over all the glaciated portions of the state. Such a study probably can be carried on to the best advantage under the organization of a State Survey. But independent workers can do much to throw light on these deposits by collect- ing the records of well-borings and by careful notes taken at natural or artificial exposures. Before entering upon the discussion of the Indi- ana drift a few words of explanation seem neces- sary concerning the material of the drift, and con- cerning the gathering grounds of the ice which *See sixteenth, seventeenth and eighteenth reports of State Geologist. Tin: lx land Educator 26 overspread this region. The latter subject, how- ever, has been so well covered by Mr. Taylor that but little need be added. MATERIALS OK THE DRIFT. It is quite a prevalent idea that the bowlders which strew the surface of the glaciated districts C and which have suffered a transportation from distant regions, constitute the most impressive evidence of ice action. It seems by many not to be understood t hat the thick deposits of stony clay with associated beds of sand and gravel which blanket the North Central States to a depth of 1(K), 200 feet, and occasionally 500 feet, are also due to ice transportation. Over a large part of the, coun- try from the Dakotas eastward to the Appalachian ranges, these deposits arc so thick that ordinary wells fail to reach their bottom, and many of the valleys of the large streams are formed entirely in them. The bowlders in reality constitute but an i/ insignificant portion, for probably ninety-five, per cent, of the drift of these states consists of minute rock fragments and sand and clay, and of the remaining five per cent, only a small part is made up of large blocks of distant derivation; •/. e., of bowlders proper. An examination of rocks in the drift mass will usually disclose a large percentage of material which has not been transported far, but there is usually to be found a Sprinkling of rocks from dis- tant localities. Let the reader select some space, sav a square yard, in a gravel pit or other exposure and set about classifying the several kinds of rocks represented, and he will ascertain the relative amount of local and distant material. (/ In its bedding the drift displays great irregu- larity. In general, it consists of a confused mass of angular, semi-angular, and well-rounded stones imbedded in a matrix of sandy clay. This confused mass was named till by Scottish geologists, and this term has been adopted by American geologists. By some it is called bowlder clay because of its containing bowlders. With the till one can find, in many exposures, beds or pockets of sand and gravel. These beds in some cases comprise the entire section, but they are usually subordinate to the till. In some parts of the glaciated districts the till j / constitutes the lower part of the drift, while the sand and gravel lie mainly near the surface. In Indiana such a relationship does not prevail over wide areas. The drift deposits of this state are unusually varied in the arrangements of till sheets, gravel beds and sand beds ; what is true of one township may find no application in a neighboring one. ‘■•Inland Educator, Yol II , pi>. ioa, 138. Farther on we shall discuss the evidence upon which is based the conclusion that there are in Indiana drift-sheets differing widely in age. GLACIATED ROCK SURFACES. The peculiar appearances presented by rock sur- faces which have been abraded by the ice-slieet are usually of such a striking nature as to arrest the attention of untrained as well as of trained ob- servers. These surfaces differ somewhat from place to place but still have a characteristic appearance. They present, usually, a series of parallel or but y slightly divergent lines or grooves, varying in size from faint scratches as fine as a hair, to broad shallow grooves an inch or two, and occasionally several inches in widt h. Between the grooves the rock has usually been scoured down to a plane surface. The stria- indicate, as a rule, the general course of ice-movement and with few exceptions point toward the margin presented by the ice- sheet at the time they were formed. As the ice-sheet was subject at times to excessive I wastage, if not to complete destruction, followed by readvance in which some shifting of movement ip occurred, we find the striae showing some interest- ing variations in neighboring localities. Some of the best illustrations in America are to be found in Western I ndiana and these are discussed farther on. TIIE GLACIAL GATHERING GROUNDS. On the glacial map of North America are shown the extent of glaciation, and the several main cen- ters of dispersion; viz., the Cordilleran, Keewatin, Labrador, and Greenland. The glaciated districts in North America are estimated to cover 4,tKX),(KK) square miles. It is doubtful, however, if this en- tire area was covered by the ice-sheet at any one time. Dr. G. 51. Dawson, director of the Canadian Geological Survey, has found evidence that the Cordilleran ice-field overspread the Rocky Moun- tains and extended some distance to the east and then withdrew before the Keewatin ice-sheet had reached that region *. Similarly the Keewatin ice-sheet culminated and wit hdrew from its southern limits ( in Missouri and Iowa) before the Labrador ice-field had reached its extreme western limits. The writer has found that the Labrador movement extended into South- eastern Iowa at a date considerably later than the time when the Keewatin ice-sheet withdrew; there being a sril and other evidences of an ''nterval found on the surface of the Keewa* - 1 drift and under the drift of the Labrador s=l et - !*■ should be understood, however, that tb Auction in size of the Cordilleran and Keew -sheets at the time of the culmination of tb ' L,a 1J 01 sheet, may # Bulletin of the Geol. Soc’p Vl " Lri va, \ ol. A II. pp. _> November, 1S95 Titt: Itstuand Educator. 27 have amounted to but a small percentage of the area which they had covered. Greenland is now ice-covered while districts to the west which have been ice-covered are nearly free from glaciers. The continuation of glaciation there parallels the observations in the fields to the west and adds to the weight of these observations in indicating a progressive culmination of the ice- sheet from west to east. Aside from the four main gathering grounds there appear to have been minor gathering grounds in the extreme east on New Brunswick and on Nova Scotia as indicated by Mr. Robert Chalmers in his paper in the Annual Report of the Canadian Sur- vey for 1894. There were also small ice-fields on the Rocky and Sierra Nevada Mountains in the Western United States, as described many years ago by King, Whitney and others. THE GLACIAL SUCCESSION IN INDIANA. First Tee Invasion. This state was invaded by ice which had as its center of dispersion the elevated districts to the east and south of Hudson Bay. There was a movement from the region north of Lake Huron in a course west of south over the Lake Michigan basin, Illinois and Western Indiana. There was also a southward movement from the same region across Lakes Huron and Erie, Western Ohio and Eastern Indiana. It is not known whether these movements were independent and of differ- ent dates or whether there was simply a radiation in movement of a single ice accumulation. It should not be taken for granted that even within the state of Indiana the ice-sheet was occupying the glacial boundary completely at any one time. The ice deposited but little drift near its extreme limits, either in Indiana or states to the west. There is not, as a rule, a Avell defined ridge or thick belt of drift along the glacial boundary, such as characterizes the southern limit of some of the later drift-sheets, though occasional ridging of drift is to be seen, as in Chestnut Ridge in Jackson county* and a similar ridge in Southern Morgan county. The boundary of the drift in Indiana is usually so vague and ill defined that it is only approximately known. (See note accompanying Glacial Map of Indiana.) If we may judge of the deposit over the state from the outlying portions, south of deposits made by later invasions, the deposits of the first invasion are of much less volume than those of later inva- sions. They appear to include not more than 30 of the 130 feet which the writer estimates the state to carry. In the portion of the state which was glaciated but once the thickness is usually less than 25 feet, but filled valleys will probably give it an average somewhat above that amount. What is * Geology of Indiana, 1871, pp. 56-57. true of the drift of the earliest invasion in South- ern Indiana is true also of the same drift of South- ern Illinois and Southwestern Ohio. This invasion seems, therefore, to be quite widely characterized by a lighter deposition than that of later invasions. First Interglacial Interval. After reaching the line marked by the glacial boundary, the ice melted away and left the drift exposed to atmospheric agencies. How far to the north the land became uncovered is not known. At this time a black soil was formed, which is now concealed beneath depos- its of silt, termed loess, in Southern Indiana, and be- neath later deposits of till in the northern portion of the state. This soil is found at the base of the loess at various points over the southern portions of the state, but is best developed on flat tracts. It may be seen beneath the loess in the flat dis- tricts east and south of Terre Haute at a depth of from six to eight feet. The vegetable matter appears to have accumulated there just as it does on the present surface of poorly drained tracts in northern latitudes, where decay is slower than accumulation. In Western Indiana, from Parke and Vermillion counties northward, the soil is found below a later sheet of till at depths varying from twenty feet up to one hundred feet or more. Numerous references to the soil below till in this portion of the state are to be found in the Indiana Geological Reports. It has not been observed in Eastern Indiana, so far as the writer is aware, but may be present, for few valleys there reach low enough to expose it. It seems not to be so conspicuous, however, as in Western Indiana, otherwise it would have been brought to notice in well-borings. No conclusions have been reached concerning the length of time involved in the formation of this soil. The land at that time seems to hav^e been so low or so flat in Indiana, that drainage lines were not well developed in the drift surface, and we are thus deprived of one important means of estimating the work accomplished. Main Loess Depositing Stage. Loess is a term applied to a fine-grained yellowish silt or loam, which overspreads the southern portion of the glacial drift in North America, and extends thence southward on the borders of the Mississippi valley to the shores of the Gulf of Mexico. The term was originally applied to deposits of this character on the Rhine, which have very extensive development in the German lowlands and bordering districts in Northern Europe. Microscopical analysis shows it to consist principally of quartz grains, but it usually has a variety of other minerals such as occur in the glacial drift. It is apparently derived from the drift, either by the action of water or wind. In many places, especially on the borders of the large valleys, the loess is charged with cal- 28 Tiie Tnxand Educator. careous matter which partially cements it. When excavations are made in it the banks will stand for years, and will retain inscriptions nearly as well as the more consolidated rock formations. It has a strong tendency to vertical cleavage, and usually presents nearly perpendicular banks on the bor- ders of streams which erode it. It often contains concretions or irregular nodules of lime and of iron and manganese oxides. It is also often highly fos- j siliferous. The fossils are usually land and fresh- water mollusks, but occasionally, insects and bones of mammals are found. The deposit appears to be mainly of one stage in the glacial period, and has been definitely corre- lated by Mr. W. J. McGee with an ice invasion which followed the interglacial stage just dis- cussed.* In the region which Mr. McGee studied, in Northeastern Iowa, it connects on the north with a sheet of till called by him the upper till, and afterwards named by Professor Chamberlin, the Iowan Drift-Sheet. The writer has visited that region and fully concurs with Mr. McGee’s opinion. This drift-sheet has not been recognized in Indiana, for if present it lies entirely within the limits of a later invasion and the later deposits have con- cealed it. There is, in Western Indiana along the Wabash, a loess of more recent date than the main deposit, but it is confined to low altitudes, seldom appearing more than one hundred feet above the river level. In Western Illinois, a loess has been found which is older than the main deposits, but it has been seen in only a few places and is apparently a thin and perhaps patchy deposit. It is thought by Pro- fessor Salisbury that the loess of the lower Missis- sippi was deposited at two distinct stages. Loess is, therefore, a deposit which, like sand or gravel, may be laid down whenever conditions are favor- able, but the great bulk of it having been deposited at a definite stage of the glacial period, it seems proper to refer to that stage as the Loess stage. In Southern Indiana, and in bordering portions of Southern Ohio and Southern Illinois, there is a continuous sheet of pale silt locally termed “ white clay, ” which is thought to be a phase of the loess, though more clayey and less uniform in texture than typical loess. It covers the interfluvial tracts as far north as the limits of a later sheet of drift, and has been discovered at a few places beneath that later drift. It probably extended much farther north than its present exposed limits, for the ice- sheet appears to' have receded far to the North at the main loess-depositing stage, thus leaving the surface free to receive these deposits. The north- ern limit of the exposed portion in Indiana is j -Eleventh Annual Report, U. S. Geol. Survey 1SS9-90, pp 435-471. marked by the “ Wisconsin boundary,” shown on the Glacial Slap of Indiana. This deposit is usually but a few feet in thickness, seldom exceed- ing eight feet. Along the Wabash, however, where it becomes a typical loess it often reaches a thick- ness of twenty to twenty-five feet. It may be readily distinguished from the underlying till both by tex- ture and color. It contains only very minute rock fragments, while the till is thickly set with stones of all sizes. In color it is paler yellow than the till. There is usually, also, a weathered zone at the top of the till and sometimes a black soil, making still more clear the line of contact. The loess and its associated silts is found at all altitudes in Southern Indiana ; from the low tracts near the Wabash, scarcely 400 feet A. T., up to the most elevated tracts in Southeastern Indiana, which in places exceed 1,000 feet A. T. The great range in altitude is one of the most puzzling feat- ures of the loess. The same perplexing distribu- tion is found in Europe as in America. As yet, no satisfactory solution for the problem of its deposi- tion at such widely different altitudes has been found. Interglacial Stage Following the Loess Depos'tion. Between the main deposition of loess and the in- vasion of Northern Indiana by a later ice-sheet, considerable time elapsed ; for we find that the drainage lines have reached a much more advanced stage on the loess-covered districts south of the deposits of the later ice-sheets than they have upon those deposits. It is found that large valleys had been opened in the loess and the underlying drift before the streams from the later ice-sheet brought their deposits into the valleys. This interval of val- ley-erosion is thought by several who have had op- portunity to study it, including the present writer, to be longer than the time which has elapsed since the ice-sheet last occupied Northern Indiana. The question has been raised, whether the greater amount of erosion outside the later drift may not have been due to streams of large volume which accompanied the later ice invasion. That this is only a minor influence, is shown by the fact that valleys in Southern Illinois which lie entirely out- side the reach of such waters are much larger than valleys of similar drainage areas within the limits of the later drift-sheet. It cannot be urged that the region with the smaller valleys is less favored by slopes or stream gradients than the region with well-developed valleys, for the reverse is the case. There are large areas within the loess-covered districts which do not possess the reliefs and other conditions favora- ble for the rapid development of drainage lines which appear in much of the newer drift. In short, there appears no escape from the view, that the \ )/ 80 The J^ixand Educator. interval between the loess deposition and the later ice invasion was a long one. The yV'ixcomin Stage of Glaciation. After the in- terglacial interval just mentioned, there occurred one of the most important stages of glaciation in the entire glacial period. It is marked by heavier deposits of drift than those made at any other invasion. Throughout much of its southern boun- dary in the -United States, a prominent ridge of drift is to be seen rising in places to a height of 100 feet or more above the outlying districts on the south, and merging into plains of drift on the north which are nearly as elevated as its crest. At this time the ice reached its farthest exten- sion in New England, and also in much of the dis- trict between New England and the Scioto River in Ohio. From the Scioto westward, however, it usually fell far short of extending to the limits of the earliest ice invasion. In Illinois it fell short about one hundred miles and in Iowa a still greater distance, but projected into the edge of the Drift- less Area in Wisconsin. Partly because of this development in Wisconsin, Professor Chamberlin has called it the Wisconsin Drift Sheet. The lim- its of this ice invasion appear on the small map of North America. The southern border of this drift-sheet in Indi- ana is less conspicuous than that in the states to the east and west. The ridge on its south-border in Western Indiana rises scarcely twenty feet above the outer border tracts, and it is no more conspicu- ous in Central Indiana. Indeed, from near Green- castle to the vicinity of Columbus there is not a well defined ridging of drift along the border ; the limits there being determined by the concealment of the loess beneath a thin sheet of bowldery drift. From the east border of East White River a few miles below Columbus, northeastward to 'White- water valley at Alpine in Southern Fayette county, there is a sharply defined ridge of drift standing twenty to forty feet above outer border tracts. Upon crossing Whitewater, where the border leads southeastward, it is not so well defined as west of the river, though there is usually a ridge about twenty feet in height. Although not conspicuous in Indiana by its re- lief, this border is about as clearly defined as any- where in the United States. Within the space of a half a dozen steps one will pass from loess-cov- ered tracts of earlier drift to the bowldery drift of this later invasion. Accompanying the change from loess to bowldery drift, there is a change in the color of the soil from a pale yellowish or ashy color to a rich black. This line is one of great agricultural importance. The district lying to the north is finely adapted to corn and timothy, while that to the south seems poorly adapted to these crops. The southern district when uncultivate soon becomes thickly covered with briers, a feature which is not common on the black soil of tl bowldery drift. In this connection we won remark, that while the loess Juts usually great fertility, (he compact loess of Southeastern Indian; is adapted only to certain products. It seems a well adapted to wheat, orchards, and small fruits a the black soil, and there appears to be an apprecia tion on the part of the residents of this restricted adaptability. Between the time when the ice-slieet stood a the line just discussed, and the final disappearance of the ice from Indiana, several moraines wer formed. The best defined ones are indicated oi the accompanying State map. In a few places not indicated on the map, weak morainic lines hav been observed but their courses and connection have not been fully determined. These moraines indicate considerable complex . ity of movement. It will be observed that several 'moraines lead eastward from Illinois into Warren and Benton counties, Indiana, and that their east- ern ends are crossed by weaker morainic belts car- rying many bowlders. These features appear to indicate that after the former moraines had been made and the ice had retreated some distance nortli- j^Avard, there was a readvance of ice from the north- east to the line marked by the outer bowlder belts. It is as yet undecided whether much of an interval of deglaciation preceded this advance, but there was apparently a great shifting of ice-movement. The prominent moraines which are overridden in Benton and Warren counties mav find a con- tinuation eastward in a belt of very thick drift which crosses Central Indiana from Benton county- eastward, but which has not the definite ridges which are to be seen from Benton county west- ward. This belt of thick drift in Indiana is fifteen to thirty miles wide, and has a thickness perhaps three times as great as the general thickness of drift in bordering districts north and south of it. The average thickness is fully 200 feet. It leads south of east across Tippecanoe and Clinton conn ties to Western Tipton county where it turns abruptly southward through Eastern Boone and Western Hamilton counties and Marion county, coming to White River in the vicinity of Indianap- olis. It there turns eastward and passes through Hancock, Henry and Northern Wayne and South- ern Randolph counties into Ohio. This belt oi thick drift was apparently overridden by the late advance. The weak moraines and bowlder belts of the later advance cross it obliquely in a north west to southeast course in Western Indiana, am return in a northeastward course to it in Henry, Wayne, and Randolph counties. TOR ’.1 This later advance apparently exten™d as far | southwest as the bovldery moraine of Central .Hendricks county and the bowldery morainic tracts of Southern Johnson and Southern Shelby comities. |l ' Its northwest limits were perhaps at the curving belt in Iroquois county, Illinois, and Newton and * Jasper counties, Indiana, though there was possi- _ bly only a reentrant angle at that line with a Lake Michigan ice-lobe on the northwest. From this outer limit of the later advance the ice-sheet appears to have shrunk on all sides until ' its limits on the northwest were at the moraine which lies along the north side of the Wabash in the vicinity o{ Logansport, and at the southwest were near the dotted line indicated on the Indiana map, leading from White county southeast to the vicinity of Indianapolis. It is in the district southwest of the latter line that feeble moraines and patches of bowlders are found crossing over the great belt of drift in oblique courses. From near Indianapolis, the line marking this later posi- tion of the last invasion, as shown on the map, leads eastward to the strong belt in Southeastern Delaware county. There appears to have been at the stage just outlined, a lake bordering the ice on the northwest in which the deposits of sand were made which form such a conspicuous feature in Northwestern Indiana from Cass and White counties northwest- ward to the moraine north of the Kankakee. It seems probable that the eastern and northern, as well as the southeastern limits of this lake were determined by the ice, for we find that the sandy districts terminate at moraines on these borders. The moraine leading northward from Northern Fulton county through Western Marshall and St. Joseph counties, would in that case, be about con- temporaneous with the moraine on t he north side of the Wabash in Southwestern Fulton, Miami, Cass, Carroll and White counties, and both would be of about the same date as the strong moraine lying north of the Kankakee. These correlations are not, however, fully established and should be taken simply as a working hypothesis to be tested by future developments in the study of t hat region. In Northeastern Indiana, moraines appear along the north border of the Mississinewa, Salamonie, Wabash and St. Mary’s rivers, which were appar- ently formed in succession as the ice was wasting away after its last advance. These moraines are traceable eastward across Northern Ohio and north- eastward into Southeastern Michigan and mark successive limits of a lobe of ice which flowed south westward across the Erie and Maumee basins. This ice-lobe appears to have persisted at the line of the outer of these four belts to a date wlven there was open country on the northwest, for the drainage lines lead from this morainic belt north- west to the St. Joseph river, passing across the moraines of the intervening district, as they would scarcely have done had the, ice persisted there as long as in the Erie lobe.* Having traced the ice-sheet to its final disappear- ance from Indiana, the reader may find in Mr. Taylor’s History of the Great Lakes a continuation of the events incident to the retreat of the ice to- ward Labrador f. SUCCESSION OF ICE INVASIONS SHOWN BY DRIFT > DEPOSITS. The evidence of difference in the age of the drift, shown by erosion of its surface, has been discussed. Other lines of evidence of successive invasions have been recognized. One of the most interesting and significant is the presence in a vertical section of sheets of drift showing differences of age and of derivation. Such sections are occasionally seen along streams, and are frequently brought to light by wells. Professor Chamberlin has presented as the frontispiece illustration in Geikie’s last edition of “The Great Ice Age,” such a section found on Stone creek near Williamsport in Warren county, Indiana. There is exposed at the base, a reddish till of the earliest drift upon which there rests a bed of old ferruginous gravel. This gravel is overlain by a fresh blue till, which is apparently of the age of the moraines which lead into that county from the west. Above this till is another gravel bed much fresher than the one below. Above the gravel is a gray till, which was apparently deposited by the ice at the time when it fronted southwest, and had its terminus at the bowlder belt which crosses Warren county from north to south just west of the place where this section is exposed. SUCCESSION OF ICE INVASIONS SHOWN BY ST RLE. The strite of Western Indiana, as may be seen by the maps, are widely different in their bearings. Until the several ice invasions had been recognized they were a puzzling feature; but they are now found to support the other lines of evidence of such invasions. Perhaps the best illustration is to be found near Williamsport. There are found in this village two sets of strife ; one bearing southeast and belonging apparently to the earliest invasion ; another bearing southward and belonging appar- ently to the same invasion which formed the bulky moraines in that vicinity. Two miles east of Williamsport, on the north side of the Wabash, Professor Chamberlin found a third set of striae, with westward-bearing, which apparently pertain to the last invasion of the ice. At Monon and near Kentland, strife pf two dis- *See 18th Report Incl. State Geologist, pp. 29, 89. Inland Educator, Vol. II. p. uts, 2l(>. 32 The, tinct sets appear. The latest bear westward and belong, apparently, to the last ice invasion. The date of the earlier, southward-bearing striae, is as yet undetermined. THICKNESS OF THE DRIFT. There are surprising differences in the thickness of the drift within the state. The portion of the older drift exposed to view has, as already noted, an average thickness of about thirty feet. The additional 100 feet of the newer drift is, however, deposited very irregularly. In the beltof thick drift which leads from Benton county southeast to Marion county, and thence east into Ohio, the thickness is probably 200 feet. The portion of the newer drift area to the south of this belt has an average of about fifty to seventy-five feet. A still larger tract extending north from this belt of thick drift as far as Allen county and the west-flowing portion of the Wabash, has only fifty to seventy- five feet with limited areas where its thickness is but twenty to thirty feet. In Northwestern White, Southwestern Pulaski, and Southern Jas- per counties there are several townships in which scarcely any drift appears excepting bowlders and sandy deposits. In Northern Indiana the drift is very thick. Its average thickness for fifty miles south of the north boundary of the state is prob- ably not less than 250 feet, and may exceed 300 feet. At Kendallville it is 485 feet, and at several cities on the moraine which leads northeast from Fulton county to Steuben county, its thickness has been shown by gas borings to exceed 300 feet. The rock is seldom reached in that region at less than 200 feet. Were the drift to be stripped from the northern portion of Indiana its altitude would be about as low as the surface of Lake Michigan, though much of the present surface is 200 to 300 feet above the lake. Denmark, Iowa. Method in Arithmetic.— XII. Typical Plans — Finding the Area of a Circle. fhe area of a circle is found by multi- plying the diameter sepia red by .7854. 3. The area of a circle is found by multi- plying the scpiare of the radius by 3. 14 hi. The first is chosen as the form to be learned in this lesson. The book definition need not be studied antecedently to the lesson. The truth is to be developed from the nature of the triangle and the circle and their relations to each other. II. Purposes in the mind of the teacher ; effects upon the minds of the pupils. 1. To give the pupils a knowledge of the subject matter, that the circle’s area may be found by multiplying the circumfer- ence by one-half the radius. 2. To arouse pleasurable emotions in this search for and mastery of new truths. 3. To affect the will in the entire process for immediate and remote results. III. Movements of mind in learning this new truth. 1. Rethinking a particular triangle. a. Its form and parts. b. Its area as equalling the product of one-half its altitude by its base, which is easily generalized. 2. Rethinking a particular circle, a. Its form and parts. 3. Thinking this circle as made up of sev- eral triangles whose bases are equal. a. The sum of whose bases equals the circumference. b. Whose altitudes equal the radius. 4. Thinking the area of the circle is equal to the sum of the areas of the triangles, and is the product of the circumference by one-half the radius. 5. Thinking this process as general, the area of any circle may be so found. 6. The association of the particular and general until the truth is fixed, the sub- ject matter is a possession of the pupil. Mensuration should be one line of work in the grades of a well-organized school. The relations of number and form, of arithmetic and geometry, should be kept in mind by the teacher and progressively learned by the pupil. To illustrate the general work in teaching such relations the following is given, a relation between the triangle and the circle : I. The general subject-matter is the process of finding the area of a circle. This may be one of several processes. 1. The area of the circle is found by mul- tiplying the circumference by one-half the radius. IV. Basis for this work, the known whence the process advances. 1. A knowledge of the triangle, its parts, and the process for finding its area. 2. A knowledge of the circle and its parts, at least the circumference and radius. 3. Some experience in working out similar ideas. Y. Devices or means used in the process of teach- ing this particular subject. 1. A triangle, to cause the rethinking of its parts and their relation to the area. 2. A circle cut into any number of equal triangles. To lead to thinking the equiv- V ' / \