m 
 
 
STATE OF ILLINOIS 
 DEPARTMENT OF REGISTRATION AND EDUCATION 
 
 DIVISION OF THE 
 
 STATE GEOLOGICAL SURVEY 
 
 M. M. LEIGHTON. Chief 
 REPORT OF INVESTIGATIONS-NO. 17 
 
 THE LIMESTONE RESOURCES OF THE PONTIAC- 
 FAIRBURY REGION 
 
 BY 
 J. E. LAMAR 
 
 PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS 
 
 URBANA, ILLINOIS 
 1929 
 
Digitized by the Internet Archive 
 
 in 2012 with funding from 
 
 University of Illinois Urbana-Champaign 
 
 http://archive.org/details/limestoneresourc55717lama 
 
STATE OF ILLINOIS 
 
 DEPARTMENT OF REGISTRATION AND EDUCATION 
 
 A. M. Sheltox, Director 
 
 BOARD OF 
 
 NATURAL RESOURCES AND CONSERVATION 
 
 A. M. Sheltox, Chairman 
 
 Edsox S. Bastix, Geology Henry C. Cowles, Botany 
 
 William A. Noyes, Chemistry Charles M. Thompsox, Representing 
 
 Johx W. Alvord, Engineering the President of the University of 
 
 William Trelease, Biology Illinois 
 
 THE STATE GEOLOGICAL SURVEY DIVISION 
 M. M. Leightox, Chief 
 
 Jeffersons Printing & Stationery Co. 
 
 Springfield, Illinois 
 
 1929 
 
CONTENTS 
 
 Page 
 
 Introduction 7 
 
 Summary 7 
 
 General geography 7 
 
 Transportation 7 
 
 Topography 8 
 
 Genera] geology 8 
 
 The Pontiac limestone 11 
 
 General character 11 
 
 Chemical composition 12 
 
 Results of physical tests 16 
 
 Strata associated with the Pontiac limestone 16 
 
 Distribution of the Pontiac limestone 17 
 
 Area 1 17 
 
 Area 2 19 
 
 Area 3 19 
 
 Area 4 20 
 
 Area 5 21 
 
 Area 6 21 
 
 Area 7 21 
 
 Area 8 : 21 
 
 Other data of interest 22 
 
 Point 9 22 
 
 Point 10 22 
 
 Point 11 22 
 
 Point 12 22 
 
 Point 13 22 
 
 Testing for areal distribution 23 
 
 Uses of the limestone 23 
 
 Agricultural limestone 23 
 
 Concrete aggregate 23 
 
 Macadam roads 24 
 
 Railroad ballast 24 
 
 Flux 24 
 
 Lime 24 
 
 Portland cement 25 
 
 Fuel for burning cement 26 
 
 Conclusions 27 
 
ILLUSTRATIONS 
 
 Figure Page 
 
 1. Index map showing the location of the Pontiac-Fairbury region 8 
 
 2. Maps of the Pontiac-Fairbury region 9 
 
 3. Graphic log of shaft of the Murphy, Linsky and Kasher Coal Company 10 
 
 4. Pontiac limestone in Area 1 11 
 
 5. General view of the quarry in Area 1 18 
 
 6. General view of the quarry in Area 3 19 
 
 7. Near view of limestone in Area 3 20 
 
 TABLES 
 
 Table Page 
 
 1. Chemical analyses of samples of limestone taken b\ the Illinois State Geological 
 
 Survey 13 
 
 2. Chemical analyses of limestone from Area 1 — Test boring A 14 
 
 3. Chemical analyses of limestone from Area 1 — Test boring R 15 
 
 4. Chemical analyses of limestone from Area 1 — Test boring C 15 
 
 5. Chemical tests of limestone from Babcock quarry — Area 1 16 
 
 6. Results of physical tests on Pontiac limestone 16 
 
 7. Chemical analyses of clavs 1 7 
 
THE LIMESTONE RESOURCES OF THE 
 PONTIAC-FAIRBURY REGION 
 
 By .7. E. Lamar 
 
 INTRODUCTION 
 
 In the summer of 1928 the State Geological Survey received inquiries 
 regarding the commercial possibilities of the limestone deposits in the vicinity 
 of Pontiac for cement manufacture and other uses. In response to these in- 
 quiries the writer, assisted by Mr. Carl E. Dutton, made a reconnassiance 
 study of the area, the results of which serve as the basis of this report. 
 
 SUMMARY 
 
 Within the Pontiac-Fairbury region in Livingston County, Illinois, it 
 seems probable that test-drilling would outline considerable areas of limestone 
 which have a thin overburden and are close to railroad transportation. The 
 limestone is from 10 to 20 feet thick and is sufficiently extensive and of such 
 purity and physical constitution as to be of commercial promise for cement, 
 agricultural limestone, macadam roads, and possibly flux, lime, and railroad 
 ballast. 
 
 GENERAL GEOGRAPHY 
 
 The city of Pontiac is located near the center of Livingston County on 
 the Chicago and Alton Railroad, Wabash Railway and Illinois Central Rail- 
 road, 92 miles from Chicago and 192 miles from St. Louis by rail. The city 
 has a population of 7,400 and is the center of an agricultural district. 
 
 Fairbury, with a population of 2,532 is located in the south central part 
 of the county, on the Wabash Railway and Toledo, Peoria and Western 
 Railroad which intersect trunk lines for Chicago and St. Louis. It is also 
 the center of an agricultural district. 
 
 Figure 1 shows the location of the Pontiac-Fairbury region with refer- 
 ence to northern Illinois as a whole. 
 
 Transportation 
 
 The Pontiac-Fairbury region is crossed by four railroads (fig. 2). The 
 main line of the Chicago and Alton Railroad between Chicago and St. Louis 
 cuts diagonally across the northwest part of the area ; the Kempton to Minonk 
 
8 THE LIMESTONE RESOURCES OF 
 
 branch of the Illinois Central Railroad crosses the north part ; the Forest- 
 Streator branch of the Wabash Railroad crosses the entire area diagonally 
 from northwest to southeast and the Toledo, Peoria and Western Railroad 
 from Effner, Indiana, to Keokuk, Iowa, touches the southern margin. 
 
 In addition to the ample railroad facilities, the region possesses many 
 good roads. State Highways 4 and 2 parallel the Chicago and Alton and the 
 Toledo, Peoria and Western railroads respectively, and many of the secondary 
 roads are graveled or macadamized. 
 
 JO DAVIESS STEPHENSON I WINNEBAGO I g I M( . HEN a Y | LAK£ 
 
 I OGLE 
 
 keh °*%ol.et1- l _ 
 
 MERCER I I [putnamI I ' 
 
 I ] ' I ' ■) ]_ I KANKAKEE 
 
 I S TARK I MARSHAU H j uwssroH 1 
 
 l £\ KNOXp ~1 L_J agONTIACI I 
 
 FORD |__ 
 
 I L-— ^ BL00MINGTON „„„ 
 
 TA7PWELL mPlEAN T 
 
 I \— 
 
 J 1 / mason I "h r\ 
 
 "1 SCHUYLER '— JZ/ _J , „_.„ DEWITT / I CHAMPAIGN VERM 
 
 ^ /\ ~^~C I LOGAN I I 
 
 , D A M <! \ J MENARD I ' 
 
 Fig. 1. Index map showing the location of the Pontiac-Fairbury region 
 with reference to northern Illinois as a whole. 
 
 Topography 
 
 For the most part the topography of the Pontiac-Fairbury region is level 
 to gently rolling. The total relief rarely exceeds fifty feet and in most 
 localities is considerably less. The principal stream is Vermilion River which 
 with its tributaries is chiefly responsible for much of the relief. Some undula- 
 tions are due to glacial deposition. 
 
 GENERAL GEOLOGY 
 
 The limestone in question belongs to the upper coal measures which are 
 composed chiefly of shales. Although the limestone member is probably the 
 
THE I'OXTIAC-IWIRBURY REGION 
 
 Lonsdale or LaSalle, it is here called the "Pontiac" limestone because of the 
 uncertainty of its identity. 
 
 Fig. 2. Map of the Pontiac-Fairbury region showing areas and points men- 
 tioned in the text. In the upper right hand corner is an enlarged sketch 
 map of Area 1 showing the location of bore holes A, B, and C, which are 
 mentioned in Tables 2, 3, and 4 of the text. 
 
 Coal No. 7 is mined at Fairbury and was at one time mined at Pontiac. 
 The record of the formations reported to have been penetrated in digging 
 the mine shaft at Pontiac (Point 13, fig. 2) are shown in figure 3. 
 
 The local occurrence of the limestone is probably the result of the preser- 
 vation from erosion of a tract of the stone in a saddle on the LaSalle anti- 
 
THE LIMESTONE RESOURCES OF 
 
 Thic k- Depth 
 
 
 62 10- 
 f§'l'gbark 
 
 Coal ^H 
 
 Fig. 3. Graphic log of shaft of the Murphy, Linsky and Kasher Coal Company. T! 
 \7y 2 foot bed of limestone is probably the equivalent of the Pontiac limestone. 
 
THE PONTIAC-FAIRBL'RY REGION" 
 
 11 
 
 cline. The main axis of the anticline extends from the LaSalle-Utica area 
 in LaSalle County southeast through the Pontiac area. 
 
 The surficial materials consist of glacial drift and earth. The former is 
 commonly a gray or brown clay, containing pebbles and locally boulders and 
 cobbles. Its thickness varies from a few inches to probably about 30 feet. 
 The drift is overlain by black soil which mantles the entire region and varies 
 from 3 inches to about 3 feet in thickness. 
 
 Fig. 4. Near view of the Pontiac limestone in quarry 
 in Area 1, showing the fractured and thin bedded 
 character of the stone. 
 
 THE PONTIAC LIMESTONE 
 General Character 
 
 The general character of the Pontiac limestone is quite constant so that 
 the bed is readily recognizable at its various outcrops. (See figs. 4, 5, 6 
 and 7.) The stone is nodular, fine-grained, brown, light gray or bluish-gray, 
 containing numerous cavities lined with crystals of calcite. Irregular masses 
 of hydrated iron oxide are also common in cavities and along joint-planes. 
 
12 THE LIMESTONE RESOURCES OK 
 
 The limestone where unweathered is in beds 1 to 3 feet thick, but weathers 
 commonly to slabs 1 to 2 inches thick. Where weathering- has been severe 
 water has dissolved channels along joints and bedding-planes which are now 
 filled with brown earth. As a whole the limestone is much fractured, par- 
 ticularly the upper 10 to 12 feet. The principal variations found in the out- 
 crops as observed at quarries is in the amount of iron hydroxide present and 
 the extent to which the deposit has weathered. 
 
 The most extensive outcrop of the limestone is in the quarry in Area 1, 
 sec. 16, T. 28 N., R. 5 E. (fig. 2) where the sequence of beds exposed is as 
 follows : 
 
 Pontine limestone exposed In quarry, Area 1 
 
 Thickness 
 Feet Inches 
 
 3. Limestone, gray, porous, locally spotted brown by iron hydroxide 11 
 
 2. Limestone, similar to limestone above but less porous and bluish-gray 
 
 in color ; grades into bed above 3 
 
 1. Limestone, bluish-gray, clayey, fossiliferous 1 2 
 
 This three-fold division is common to most outcrops of the stone. Bed 
 No. 2 is probably an unweathered phase of bed No. 3. In the deeper quarries 
 bed No. 1 is almost invariably reported to occur below the bluish stone. 
 
 In the shaft of the Pontiac mine (fig. 3) the \7y 2 feet of limestone en- 
 countered at a depth of 36 feet is probably the equivalent of the limestone 
 outcropping in the general region. Outside the immediate vicinity of the 
 mine shaft the overlying limestone beds are absent; the underlying limestones 
 are not known and may thin and disappear. 
 
 Chemical Composition 
 
 Because the Pontiac limestone has been quarried locally in many places 
 it is possible to secure a more complete set of samples for chemical and 
 physical analysis than is normally the case for undeveloped limestone deposits 
 of its type. In addition to the results of tests made on samples taken by the 
 Survey, a very detailed set of analyses of the limestone in Area 1 (see inset 
 fig. 2) are presented through the courtesy of Miss May H. Babcock, owner 
 of the quarry in Area 1. They are significant in that they show the vertical 
 differences in the composition of the limestone. 
 
THE rOXTlAC-FAIRBURY REGION 
 
 | q 
 
 'in c/5 
 
 1.33 
 
 5.44 
 
 25.34 
 4.64 
 1.12 
 
 •| o" 
 
 C\ 00 rn ^O C\ 
 r-i o .-< © © 
 
 ■c s o m 
 
 £ o £ 
 
 ft- o — i t- lo 
 
 O C\ u-j t^ O 
 
 © © o © o 
 
 Magnes- 
 sium 
 Oxide 
 MgO 
 
 .-( y-h -f CO i-< 
 
 ©' o © o © 
 
 Magnes- 
 
 sium 
 Carbon- 
 ate 
 MgC0 3 
 
 00 o\ O 00 o 
 
 o © o --< © 
 
 5 4j o 
 u ° 
 
 N «-H C\ -I" © 
 
 f^i o od •-< eo 
 
 Calcium 
 Carbon- 
 ate 
 CaCO.. 
 
 93.50 
 89.20 
 
 68.75 
 91.56 
 95.05 
 
 
 Limestone, gray 
 
 Limestone, blue . 
 
 Limestone, blue, 
 argillaceous. . 
 
 Limestone, gray . 
 
 Limestone, gray . 
 
 o 
 
 Area 1 
 Area 1 
 Area 1 
 
 Area 8 
 Area 3 
 
 & 6 
 in 
 
 M <*3 T O CO 
 
 CU Ol di Oh' Oh' 
 
TIIK !.l.MI-Mn\K KKSOIIUKS OF 
 
 Table 2. — Chemical analyses of limestone from Area 1 
 Test Boring A (See fig. 2) 
 
 Depth 
 
 (Feet) 
 
 CaCO s 
 
 MgC0 3 
 
 CaO 
 
 MgO 
 
 Fe 2 3 
 
 A1,0 3 
 
 Si0 2 
 
 Phos- 
 phorous 
 
 Total 
 
 6 
 
 87.2 
 
 2.02 
 
 48.82 
 
 0.96 
 
 0.99 ' 
 
 2.13 
 
 8.30 
 
 .025 
 
 100.66 
 
 8 
 
 94.6 
 
 0.86 
 
 53.09 
 
 0.41 
 
 0.99 
 
 0.81 
 
 2.76 
 
 .019 
 
 95.90 
 
 10 
 
 94.6 
 
 1.74 
 
 53.03 
 
 0.87 
 
 0.70 
 
 1.58 
 
 1.40 
 
 .017 
 
 100.40 
 
 12 
 
 92.6 
 
 1.61 
 
 51.80 
 
 0.77 
 
 1.48 
 
 2.13 
 
 0.92 
 
 .019 
 
 98.76 
 
 14 
 
 91.6 
 
 1.40 
 
 51.36 
 
 0.67 
 
 1.60 
 
 2.58 
 
 1.16 
 
 .018 
 
 98.30 
 
 16 
 
 90.4 
 
 2.08 
 
 51.06 
 
 0.99 
 
 1.48 
 
 2.05 
 
 2.74 
 
 .024 
 
 98.77 
 
 18 
 
 75.0 
 
 3.11 
 
 42.0 
 
 1.48 
 
 1.72 
 
 4.86 
 
 13.84 
 
 .033 
 
 98.56 
 
 20 
 
 62.5 
 
 3.48 
 
 35.0 
 
 1.74 
 
 1.97 
 
 8.93 
 
 22.22 
 
 .042 
 
 99.14 
 
 22 
 
 46.1 
 
 5.38 
 
 26.81 
 
 2.56 
 
 3.90 
 
 14.63 
 
 27.64 
 
 .025 
 
 98.67 
 
 Average 
 
 
 
 
 
 
 
 
 
 
 (6'-16') 
 
 91.72 
 
 • 1.63 
 
 51.53 
 
 0.78 
 
 1.21 
 
 1.88 
 
 2.88 
 
 .020 
 
 100.30 
 
 Average 
 
 
 
 
 
 
 
 
 
 
 (18'-22') 
 
 61.58 
 
 3.99 
 
 34.60 
 
 1.93 
 
 2.53 
 
 9.47 
 
 21.23 
 
 .033 
 
 99.13 
 
THE PONTIAC-FAIRBURY REGION 
 
 Table 3. — Chemical analyses of limestone from Area 1 
 Test Boring B (See fig. 2) 
 
 Depth 
 (Feet) 
 
 CaCO a 
 
 MgC0 3 
 
 CaO 
 
 MgO 
 
 Fe 2 3 
 
 A1 2 3 
 
 Si0 2 
 
 Phos- 
 phorous 
 
 Total 
 
 6 
 
 80.2 
 
 1.70 
 
 44.91 
 
 0.81 
 
 1.11 
 
 2.82 
 
 14.40 
 
 .034 
 
 100.26 
 
 8 
 
 87.5 
 
 2.46 
 
 49.09 
 
 1.17 
 
 0.99 
 
 2.27 
 
 6.24 
 
 .040 
 
 99.50 
 
 10 
 
 92.1 
 
 1.57 
 
 51.67 
 
 0.75 
 
 0.99 
 
 1.77 
 
 4.06 
 
 .025 
 
 100.50 
 
 12 
 
 91.6 
 
 2.59 
 
 51.30 
 
 1.23 
 
 2.34 
 
 0.74 
 
 2.32 
 
 .034 
 
 99.62 
 
 14 
 
 90.0 
 
 2.79 
 
 50.38 
 
 1.33 
 
 1.72 
 
 1.02 
 
 4.24 
 
 .025 
 
 99.80 
 
 16 
 
 90.8 
 
 1.46 
 
 50.81 
 
 1.17 
 
 1.72 
 
 1.64 
 
 3.36 
 
 .059 
 
 99.04 
 
 18 
 
 88.2 
 
 3.11 
 
 49.40 
 
 1.48 
 
 1.97 
 
 1.97 
 
 4.12 
 
 .058 
 
 99.43 
 
 20 
 
 84.2 
 
 3.45 
 
 47.24 
 
 1.64 
 
 1.84 
 
 1.84 
 
 4.76 
 
 .035 
 
 96.13 
 
 22 
 
 84.6 
 
 1.47 
 
 47.44 
 
 0.70 
 
 0.62 
 
 0.80 
 
 12.68 
 
 .052 
 
 100.22 
 
 Average 
 
 
 
 
 
 
 
 
 
 
 (6'-16') 
 
 88.45 
 
 2.26 
 
 49.69 
 
 1.08 
 
 1.48 
 
 1.71 
 
 5.77 
 
 .036 
 
 
 Average 
 
 
 
 
 
 
 
 
 
 
 (18'-22') 
 
 85.49 
 
 2.65 
 
 48.03 
 
 1.27 
 
 1.48 
 
 1.54 
 
 7.15 
 
 .048 
 
 
 Table 4. — Chemical analyses of limestone front Area 1 
 Test Boring C (See fig. 2) 
 
 Depth 
 (Feel) 
 
 CaC0 3 
 
 MgCO, 
 
 CaO 
 
 MgO 
 
 Fe 2 3 
 
 A1 2 3 
 
 Si0 2 
 
 Phos- 
 phorous 
 
 Total 
 
 2 
 
 95.8 
 
 1.51 
 
 53.64 
 
 0.72 
 
 0.86 
 
 0.73 
 
 1.10 
 
 .024 
 
 100.20 
 
 4 
 
 94.6 
 
 1.68 
 
 53.02 
 
 0.84 
 
 1.84 
 
 0.81 
 
 0.74 
 
 .021 
 
 99.69 
 
 6 
 
 72.2 
 
 1.88 
 
 40.41 
 
 1.37 
 
 1.35 
 
 6.19 
 
 16.54 
 
 .012 
 
 98.17 
 
 8 
 
 88.1 
 
 2.04 
 
 49.34 
 
 0.97 
 
 1.11 
 
 2.54 
 
 6.14 
 
 .013 
 
 99.94 
 
 10 
 
 94.6 
 
 1.53 
 
 53.02 
 
 0.73 
 
 1.11 
 
 1.10 
 
 1.32 
 
 .014 
 
 99.67 
 
 12 
 
 93.9 
 
 1.41 
 
 52.66 
 
 0.67 
 
 1.35 
 
 0.95 
 
 1.96 
 
 .013 
 
 99.58 
 
 14 
 
 94.5 
 
 1.17 
 
 52.90 
 
 0.56 
 
 1.35 
 
 0.85 
 
 1.90 
 
 .015 
 
 99.79 
 
 Average 
 
 90.4 
 
 1.60 
 
 50.79 
 
 0.77 
 
 1.28 
 
 1.88 
 
 4.24 
 
 .016 
 
 99.56 
 
16 THE LIMESTONE RESOURCES OF 
 
 Table 5. — Chemical tests of limestone from Babcock quarry — Area 1 
 
 
 CaC0 3 
 
 MgCO a 
 
 Fe 2 0„ 
 
 A1 2 3 
 
 Si0 2 
 
 Total 
 
 Upper limestone, including 
 
 90.16 
 42.13 
 
 0.48 
 3.36 
 
 2.30 
 2.20 
 
 0.82 
 11.80 
 
 4.64 
 36.64 
 
 98 40 
 
 Lower limestone, clayey, blue.. 
 
 96.13 
 
 The outstanding features brought out by the analyses are: (1) the cal- 
 cium carbonate content of the limestone is commonly above 90 per cent and 
 is reasonably constant from place to place ; (2) the magnesium carbonate 
 content is with one exception consistently lower than 4 per cent and in over 
 3/5 of the samples tested was less than 2 per cent; (3) the ferric oxide, 
 alumina, and silica contents vary considerably with the calcium carbonate 
 content ; and (4) the phosphorous content is small. 
 
 Results of Physical Tests 
 
 In order to determine the value of the Pontiac stone for concrete aggre- 
 gate, road material, and the like, two samples were taken for physical analysis. 
 The results of the analyses are given in Table 6. These tests indicate the 
 character of the limestone only in the places where the samples were taken. 
 Nevertheless they give a general idea of various physical properties of the 
 stone. 
 
 Table 6. — Results of physical tests on Pontiac limestone a 
 
 Limestone Limestone 
 
 From Area 1 From Area 8 
 
 (Sample P. 9) (Sample P. 7) 
 
 Specific gravity 2.55 2.63 
 
 Weight, lbs. per cubic ft 159 164 
 
 Absorption (24 hrs.) per cent 2.0 0.6 
 
 Absorption, lbs. per cubic ft 3.2 1.0 
 
 Abras'on loss per cent 7.5 5.8 
 
 French coefficient 5.3 6.9 
 
 Soundness 2 pieces failed O.K. 
 
 (5 runs) 
 
 Strata Associated with the Pontiac Limestone 
 
 According to the data available the beds immediately below the Pontiac 
 limestone are shale, but there is no information as to the character of this 
 material. 
 
 a Tests made by Division of Highways, Bureau of Materials. Springfield, lllinoi: 
 
THE PONTIAC-FAIRBURY REGION 
 
 Unconsolidated materials overlie the limestone at all the outcrops visited 
 In some places the rock is immediately overlain by a tough, greenish-brown 
 clay m others by a pebbly, gray or brown glacial clay which is usuallv thin but 
 may he 15 or 20 feet thick in places. Where the overburden on the limestone is 
 heavy this glacial clay is probably the dominant constituent of the overburden 
 In all places the uppermost material is black soil. Locally the soil rests directlv 
 on the limestone, elsewhere on the brown clay or pebbly glacial clay. Analyses 
 indicating the general chemical composition of the various materials follow 
 
 
 Table 7.— Chemical analyses 
 
 of chiys 
 
 
 
 
 Sample 
 
 CaCO, 
 
 MgC0 3 
 
 CaO 
 
 MgO 
 
 Fe 2 3 
 
 A1 2 3 
 
 SiO, 
 
 Loss on 
 igni- 
 tion 
 
 PI — Area 1 ; from 2 
 feet brown clav and 
 
 
 
 
 
 
 
 
 
 2 feet black earth. . 
 
 1.50 
 
 0.11 
 
 0.84 
 
 0.06 
 
 4.31 
 
 5.31 
 
 77.72 
 
 6.80 
 
 P5— Area 8; from 5 
 
 
 
 
 
 
 
 
 
 feet brown clay. . . . 
 
 3.79 
 
 0.11 
 
 2.12 
 
 0.06 
 
 6.45 
 
 16.33 
 
 58.74 
 
 12.43 
 
 Area 1 ; surface clay" 3.20 
 
 1.02 1.80 
 
 0.49 j 
 
 4.30 
 
 12.38 
 
 67.00 
 
 
 
 lay H. B 
 
 abcocK. 
 
 
 
 
 
 
 
 Distribution of the Pontiac Limestone 
 
 The areal distribution of the limestone in the region southeast of Pontiac 
 as known from outcrops is shown in figure 2, page 9. In addition the lime- 
 stone outcrops at intervals along Vermilion River northwest of Pontiac to 
 approximately the township line. According to well drillers limestone is com- 
 monly encountered at a shallow depth in most of T. 28 N R 5 E T 27 N 
 
 bodies E of a , nd '^ W " * T 27 / N " R - 6 E ' ThCre are With ° llt doU ' bt s -able 
 bodies of limestone ,n most of the region outlined but these bodies are prob- 
 ably not continuous. This discontinuity is doubtless the result of stream 
 channeling and glacial erosion. 
 
 dah ?"! ops ; f , the p ? ntiac ,imestone shown in fi?ure 2 - ***** *** the 
 
 data from wells also indicated on the map, are listed and described below. 
 
 SW. 
 
 Area 1 
 V A NE. 14 sec. 16, T. 28 N., R. 5 E. 
 
 At this place a quarry about 300 by 350 feet has been a source of stone 
 tor crushed-stone roads and agricultural limestone. (Figs 4 and 5 ^ The 
 section exposed at the quarry is as follows ■ 
 
18 THE LIMESTONE RESOURCES OF 
 
 Section in quarry at Area 1 
 
 Thickness 
 Feet Inches 
 
 6. Soil, black, matted with roots 1 6 
 
 5. Earth, black 2 
 
 4 Clay, brown, breaks into grans 2 
 
 3. Limestone, gray, spotted with iron hydroxide ; numerous cavities lined 
 with calcite crystals; fracturing and jointing prominent; beds be- 
 fore weathering are 1 to 3 feet thick, after weathering 1 to 2 inches ; 
 
 grades into bed below 11 
 
 2. Limestone, similar to limestone above but less porous, less iron- 
 stained, and blue-gray in color ; grades into bed above 3 
 
 1. Limestone, clayey, fossiliferous, slabby, blue-gray 1 2 
 
 Floor of quarry 
 
 The total thickness of limestone exposed is about 15 feet, but borings in 
 the vicinity of the quarry indicate at least 22 feet of limestone (see pp. 
 
 Fig. 5. General view of the quarry in Area 1, showing the almost flat-lying 
 Pontiac limestone with a comparatively level surface and thin overburden. 
 
 14 and 15). A former workman in the quarry states that in drilling 
 blast-holes an average of about 11 feet of hard limestone was penetrated, 
 underlain by a softer bluish limestone (bed No. 1 of above geologic section) 
 which was 20 feet thick in a test hole drilled into it. There appears, there- 
 fore, to be a good thickness of limestone at this place. 
 
 The areal extent of this deposit is difficult to determine without test- 
 drilling. From the topography it seems likely that limestone with a thin 
 overburden underlies 120 to 160 acres and possibly more; other estimates are 
 that it underlies 200 acres or more. Only thorough test-drilling will accurately 
 delineate the extent of the limestone. 
 
 A large number of chemical analyses of stone from the quarry at Area 1 
 are shown in the tallies of chemical analyses (pp. 13, 14, 15. and 16). Of the 
 
THE PONTJAC-1 .MRI',1 KV RF.GIOX 
 
 samples taken for chemical analysis by the Survey during the present studies, 
 Sample P. 1 is from beds 4 and 5 in the preceding section of formations 
 (p. 17) ; Sample P. 2 from bed 3, P. 3 from bed 2, and P. 4 from bed 1 (p. 
 13) : Sample P. 9 was taken from beds 2 and 3 for physical analysis (p. 16). 
 
 NW. 
 
 Area 2 
 
 23, T. 28 N., R. 
 
 5 E. 
 
 At the northeast edge of the city of Pontiac are two abandoned quarries 
 in the Pontiac limestone. One is used as a city dump and is filled with rub- 
 bish ; the other is full of water. Very little information is available, therefore, 
 concerning the character of the stone but such as is obtainable indicates that 
 the deposit and stone are generally similar to that at Area 1 . The overburden 
 on the stone is from 2 to 5 feet thick and is largely black or brown earth. 
 
 
 
 
 
 
 <_L, ■ , /jfc 
 
 bsv; 
 
 
 
 
 Fig. 6. General view of quarry in Area 3, illustrating the irregular surface of the 
 limestone and the thin overburden. 
 
 In the most elevated parts of Pontiac, the limestone is commonly found 
 in digging sewers and basements, so it appears that a considerable tract is 
 underlain by limestone in this area. 
 
 NW, 
 
 Area 3 
 NE. y 4 sec. 1, T. 27 N., R. 5 E. 
 
 About a mile northwest of McDowell a small quarry has been a source of 
 road material and agricultural limestone. (Fig. 6.) About 15 feet of lime- 
 stone is exposed which is much less weathered than most of the deposits. 
 (Fig. 7.) Excepting the badly weathered upper 3 or 4 feet, the rock is dense, 
 fine-grained and very hard. Fossils are common. The stone lies in beds 1 
 to 8 inches thick and is mostly white. The overburden is from 1 to 4 feet 
 of black and brown earth. 
 
20 
 
 ki.-o' if. . 
 
 Sample P. 8 was taken from this quarry for chemical analysis. The 
 results of the test shown on page 13 indicate that this stone is among the best 
 sampled. 
 
 There is very little data on which to estimate the size of the limestone 
 body at this place, but the presence of two quarries at McDowell suggests 
 that a fairly extensive tract may he underlain by the stone at no great depth. 
 
 Fig. 7. Near view of limestone 
 The rock is thicker bedded than 
 
 i quarry, Area 3. 
 most exposures. 
 
 SW. }i sec. 6, T 
 
 Area 4 
 27 N., R. 6 E., near McDowell. 
 
 In the NE. corner of sec. 12, T. 27 N., R 5 E. and the NW. corner NE. 
 34 NW. Y\ sec. 7, T. 27 N., R. 6 E. respectively, are abandoned quarries 
 in the Pontiac limestone. The quarry in sec. 7 exposes 11 feet of gray lime- 
 stone with 3 to 5 feet of earth overburden. The limestone is underlain by 
 an unknown thickness of blue shaly limestone. Well drillers report 18 to 20 
 feet of limestone underlain by blue shale (probably shaly limestone) in this 
 vicinity. 
 
THE PONTIAC-FAIRBURY REGION 21 
 
 The quarry in sec. 12 is partly filled and shows only 6 feet of weathered 
 limestone overlain hy 3 to 5 feet of earth. 
 
 These exposures, though small, are significant because they suggest a 
 limestone body of considerable size in this area having an overburden averag- 
 ing less than 5 feet. 
 
 Area 5 
 Center SE. y A sec. 19, T. 27 N., R. 6 E. 
 
 A small quarry at this place which has been a source of crushed rock for 
 local roads shows 12 feet of typical weathered gray Pontiac limestone under- 
 lain by about 1 foot of blue shaly limestone. The overburden ranges from 
 practically nothing to about 2 feet in thickness. 
 
 There are no data on the extent of this deposit. 
 
 Area 6 
 Sec. 16, T. 26 N., R. 6 E. 
 
 Limestone similar to that in the Pontiac region outcrops for about a 
 third of a mile along a creek in sec. 16, about lj/j miles southwest of Fair- 
 bury. At one place the stone was once quarried for foundations and well 
 walls. In the old quarry the limestone is said to have been 15 to 20 feet 
 thick, though only about 10 feet are now exposed because the quarries are 
 filled with water. Another partly covered outcrop was noted in a barnyard 
 near the center of the SW. 34 sec - 16 and is probably a continuation of the 
 same deposit seen along the creek. 
 
 The outcrops in this area are due to stream erosion of a broad, flat hill 
 composed of Pontiac limestone. The rock hill is apparently of considerable 
 extent. 
 
 Area 7 
 NW. corner sec. 23, T. 27 N., R. 5 E. 
 
 At this place typical Pontiac limestone outcrops for a short distance in 
 the bed of small gully. The extent of the limestone is not known. 
 
 Area 8 
 Center E. line, sec. 25, T. 27 N., R. 4 E. 
 
 In digging a drainage ditch in this area typical Pontiac limestone was 
 cut through for a distance of about 1200 feet. The limestone was first en- 
 countered about a mile and a half north of the south line of Livingston 
 County ; it extends in a northeast direction, paralleling the Chicago and Alton 
 Railroad and State Route No. 4. In the ditching operations the limestone bed 
 was not penetrated for more than about 3 feet. The section exposed near 
 the center of the outcrop follows : 
 
22 THE LIMESTONE RESOURCES OF 
 
 Formations exposed in drainage ditch, Area 8 
 
 Thickness 
 Feet Inches 
 
 5. Soil, black 2 
 
 4. Clay and gravel, brown clay and fine chert gravel 4-6 
 
 3. Clay, greenish-brown, tough, irregular fracture; containing a few chert 
 
 pebbles 5 
 
 2. Gravel and clay; limestone and igneous pebbles up to 3 inches in diam- 
 eter in a clay matrix 0-8 
 
 1. Limestone, gray, porous, iron-stained 3 
 
 Sample P. 5 was taken from bed No. 3, P. 6 from bed No. 1 for chemical 
 analysis. Sample P. 7 was taken for physical analysis. The results of the 
 analyses are given on pages 17, 13, and 16. 
 
 The fact that the limestone outcrops for 1200 feet at a shallow depth in 
 the drainage ditch suggests a good sized body of stone in this area. 
 
 Other Data of Interest 
 
 In addition to tbe outcrop data presented the following information de- 
 scribed as occurring at various "Points" is of interest. 
 
 Point 9 
 SW. corner sec. 19, T. 27 N., R. 6 E. 
 
 Limestone is reported at a very shallow depth in wells. 
 
 Point 10 
 SW. corner sec. 13, T. 27 N., R. 5 E. 
 
 In the vicinity of the adjoining corners of sees. 13. 14, 23. and 24 lime- 
 stone is reported at a shallow depth. 
 
 Point 11 
 Center W. line. sec. 15. T. 27 N.. R. 5 E. 
 
 Limestone is reported at a depth of 15 feet. 
 
 Point 12 
 S. y 2 S. y 2 sec. 5, T. 27 N.. R. 5 E.. at County Farm. 
 
 Six feet of limestone was encountered at a depth of 20 feet in well. 
 
 Point 13 
 SW. corner SE. J4 sec. 15, T. 28 N., R. 5 E. 
 
 Approximate location of Pontiac coal shaft. (See figs. 2 and 3.) 
 
THE PONTIAC-FAIRBURY REGION 23 
 
 Testing for Areal Distribution 
 
 In view of the likelihood of local discontinuity of the Pontiac limestone 
 it is advisahle to thoroughly test the extent of the deposit by drilling either 
 with core or churn drills, though preferably the former because they yield 
 a better record for study and analysis of the strata penetrated. The test 
 borings will also give critical information as to the thickness of the limestone 
 which doubtless varies considerably from place to place. 
 
 Uses of the Limestone 
 
 The uses of the Pontiac limestone may be divided into two groups : 
 
 (1) those requiring simply crushing and screening of the limestone; and 
 
 (2) those necessitating burning in addition to crushing and screening. The 
 first group includes agricultural limestone, concrete aggregate, railroad bal- 
 last, flux, and other minor uses ; the second includes lime and cement. 
 
 AGRICULTURAL LIMESTONE 
 
 The function of agricultural limestone is to neutralize soil acidity and 
 thereby promote the growth of bacteria, some of which convert nitrogen 
 from the air into a form available to plants and others of which aid in the 
 decomposition of humus materials in the soil. Inasmuch as both calcium 
 and magnesium carbonates are effective in neutralizing soil acidity the total 
 of these carbonates is an approximate measure of the effectiveness of a lime- 
 stone in correcting acidity. As will be seen from the tables of chemical an- 
 alyses (pp. 13-16) the total carbonate content of the Pontiac limestone varies 
 from 90 to 95 per cent in the non-shaly part. A stone of this carbonate con- 
 tent is ordinarily considered a good agricultural limestone and this, therefore, 
 is an important use for the stone in the Pontiac-Fairbury area. 
 
 CONCRETE AGGREGATE 
 
 The physical analyses given on page 16 indicate that the limestone in 
 the Pontiac-Fairbury area is on the borderline as aggregate for concrete 
 roads and concrete for construction purposes. Regarding Sample P. 9, V. L. 
 Glover, Engineer of Material of the Illinois Division of Highways, says, 
 "This rock fails to meet our requirements as the abrasion loss exceeds the 
 maximum permitted by our specifications. Our specifications permit a loss 
 of 7 per cent whereas the tests on the rock show 7.5 per cent. 
 
 "The rock contained streaks of iron carbonate and oxide caused appar- 
 ently by the infiltration of these compounds through the voids. These streaks 
 are rather soft and are, no doubt, partially responsible for the high abrasion 
 loss which we obtained in the tests. These soft spots are rather undesirable. 
 
_4 THE LIMESTONE RESOURCES OF 
 
 especially if the rock is to be considered as an aggregate for concrete. I 
 would not consider this rock satisfactory for use in concrete road or bridge 
 work, but it may he used in macadam construction on secondary road-." 
 
 Concerning Sample J'. 7 (see p. 16) the report is. "According to our 
 tests the limestone is satisfactory. The specific gravity, absorption, and abra- 
 sion loss are well within the limits of our specifications. The soundness test 
 also showed satisfactory results." 
 
 From the foregoing it is apparent that though parts of the Pontiac lime- 
 stone are suitable concrete aggregate other parts are not. Inasmuch as there 
 is considerable variation in the character of the limestone from place to place 
 in the same quarry it seems probable that the stone can not he used exten- 
 sively for this purpose. Of the outcrops visited, the limestone in Area 3 
 seemed most likely to be an acceptable aggregate stone. 
 
 MACADAM ROADS 
 
 Water-bound macadam roads, popularly known as crushed-rock roads, 
 can be satisfactorily constructed from the Pontiac limestone of the Pontiac- 
 Fairbury region as indicated in the interpretation of the results of tests on 
 Sample P. 8 given above under the discussion of "Concrete Aggregate." 
 The limestone in general is probably slightly too soft and friable to be used 
 in primary macadam roads carrying a heavy traffic, but for secondary roads 
 the stone should give good service either in water-bound or bituminous 
 macadam. 
 
 RAILROAD BALLAST 
 
 The specifications for first-class limestone railroad ballast are about the 
 same as for concrete aggregate, and the Pontiac limestone is therefore slightly 
 on the borderline in this regard. However, the bulk of the stone would proba- 
 bly be satisfactory to many railroads. 
 
 The specifications for limestone to be used as flux vary to some extent 
 with the particular requirements of the user, but in general limestone flux 
 should contain over 90 per cent calcium carbonate, less than 5 per cent silica 
 (most fluxes contain less than 3 per cent) and be low in pyrite, alumina and 
 phosphorous. Some of the Pontiac limestone meets these requirements and 
 can probably be used as flux. 
 
 Most limestones burned for lime contain over 95 per cent total carbonates. 
 If the lime resulting contains less than 5 per cent magnesia it is known as a 
 
THE PONTIAC-FAIRBURY REGION -0 
 
 "high-calcium lime" ; if it contains over 30 per cent magnesia it is known as a 
 "high-magnesium lime." 2 If the lime contains over 5 per cent of impurities 
 such as silica, iron oxide, and alumina it is usually dark in color and is known 
 as a "lean" or "poor" lime. 3 The Pontiac limestone, because of its impurities, 
 high iron oxide content, and slightly low carbonate content, would probably 
 make a lean lime. 
 
 PORTLAND CEMENT 
 
 Portland cement is made by heating to incipient fusion an intimate mix- 
 ture of limestone and shale or clay or their equivalents, in the proportion of 
 Bout three parts of limestone to one part of shale or clay. The principal 
 substance to be avoided in cement materials is magnesium carbonate, which 
 should not exceed about 5 per cent. 
 
 The Pontiac limestone offers a good combination for cement manufac- 
 ture. Though the limestone does not contain the requisite amount of clay 
 itself, there are overlying clays and an underlying shaly limestone which may 
 be combined with the purer limestone to yield the raw cement mix desired. 
 For example in Area 1 a cement mix composed of the top earth and clay 
 (Sample P. 1, p. 17), the gray limestone (Sample P. 2, p. 13) the blue lime- 
 stone (Sample P. 3, p. 13) and the blue shaly limestone (Sample P. 4, p. 13) 
 in the ratio of their thicknesses, which are 4, 11, 3 and 3 feet respectively 
 (see p. 18) would have the following composition: 
 
 Approximate composition of cement mix, Area 1 
 
 Per Cent 
 
 CaCO s 71.83 
 
 MgCO ;i 0.34 
 
 SiO„ 19.89 
 
 A1 2 3 1.94 
 
 Fe~0 3 1.35 
 
 According to Eckel 4 the ratio of silica to alumina plus iron for ordinary 
 purposes should be about 3 to 1. In the above analysis the ratio is about 6 
 i to 1, but by the addition of shale from the bed underlying the shaly limestone 
 in the bottom of the quarry, or by employing a surface clay of somewhat dif- 
 ferent composition, as Sample P. 5. page 17, any common raw mix for cement 
 pan be produced. 
 
 In Area 8, a cement mix composed of the limestone ( Sample P. 6, p. 1 3 ) 
 and the clay (Sample P. 5, p. 17) in the proportion of 1 1 to 5, which is their 
 ipproximate thickness, would have about the following composition : 
 
 2 Eckel, E. C. Cements, limes and plasters, Wiley and Sons, New York, p. 118. 190f>. 
 
 3 Idem, p. 117. 
 *Op. cit. p. 394. 
 
26 THE LIMESTONE RESOURCES OF 
 
 Approximate composition of cement mix, Area 8 
 
 Per Cent 
 
 CaCOg 64.13 
 
 MgCO s 1.26 
 
 SiO„ 21.55 
 
 Al 2 O s 3.35 
 
 Fe 2 O s 2.52 
 
 This, though not quite fulfilling the requirements mentioned by Eckel, 
 indicates that a suitable mix might readily be obtained. 
 
 Other areas also offer opportunities for obtaining suitable materials for 
 cement manufacture. 
 
 FUEL FOR BURNING CEMENT 
 
 The manufacture of Portland cement requires a large amount of fuel ; 
 that used in Illinois is mostly powdered coal. The coal formerly mined by 
 the Murphy, Linsky and Kasher Coal Company (Point 13, fig. 2; fig. 3) 
 appears to be a potential fuel source. According to observations made by 
 Dr. G. H. Cady of the Survey staff in 1918 the coal is from 48 to 66 inches 
 thick, averaging about 57 inches. 
 
 A clay band about 3 inches thick occurs 2 or 3 inches above the floor. 
 A band of pyrite (iron sulphide) about y 2 inch thick occurs 18 inches above 
 the floor, and locally concentrations of pyrite occur in the coal itself. When 
 the mine was in operation the pyrite was removed by hand-picking. The 
 pyrite was of excellent quality, hard and stony, and it is estimated that 2 or 
 3 car-loads could have been produced monthly when the daily output was 175 
 tons of coal. An analysis made of the coal "as received" follows : 
 
 Analysis of coal from the mine of the Murphy, Linsky, and Kasher Coal Company 
 
 Moisture 9.41 
 
 Ash 13.81 
 
 Volatile matter 35.69 
 
 Fixed carbon 41.09 
 
 Sulphur 4.74 
 
 B. t. u 11.258 
 
THE POXTIAC-FAIRBURY REGION 27 
 
 Conclusions 
 
 1. In the Pontiac-Fairbury region there are tracts, some of them prob- 
 ably 200 acres or more in extent, underlain by limestone. A 200-acre tract 
 underlain by 11 feet of limestone would contain about 3,500,000 cubic yards 
 or about 7,500,000 tons of limestone. 
 
 2. Many of these tracts are located on or close to a railroad. 
 
 3. The overburden on the limestone varies from 1 to 5 feet in thickness 
 and probably averages about 3 feet. 
 
 4. The limestone is suitable for agricultural limestone, macadam roads, 
 Portland cement, probably railroad ballast, flux and lime. 
 
 5. Of these uses the outstanding one for which the limestone is not 
 now employed is the manufacture of Portland cement, which is favored by 
 the presence of a suitable limestone and associated clay, shale and argillaceous 
 limestone which provide conveniently the necessary raw materials. 
 
 6. Fuel for cement burning can probably be obtained locally. 
 
 7. The local labor supply is regarded as adequate. 
 
:cher-s m 
 
 IBRARY BINDERS 
 
 S07 3.Goodwto 
 
 Urbana.nL