,guide to the ,,geologic ,,map ,,of ,,illinois ,illinois ,state ,geological ,survey ,educational ,series #g ,,state of ,,illinois ,otto ,kerner1 ,governor ,illustration3 ,,seal ,,of ,,the ,,state ,,of ,,illinois ,,department of ,,registration and ,,education ,william ,sylvester ,white1 ,director #aifa ,,illinois ,,state ,,geological ,,survey ,john ,c4 ,frye1 ,chief ,,urbana1 ,,illinois ,,printed ,,by ,,authority ,,of ,,the ,,state ,,of ,,illinois #dbeag-bj,m #b 7#ghghc7 ,guide to the ,,geologic ,,map ,,of ,,illinois ,,glacial ,,geology ,illustration3 ,decorative capital ,although the age of the ,earth is measured in billions of years1 the face of ,illinois is young--a mere #ae1jjj years old4 ,during the ,ice ,age1 most of ,illinois was repeatedly invaded by huge glaciers1 sometimes towering a mile or more high1 that carried embedded in them ground up rock materials they had gouged out of the bedrock to the north as they ponderously pushed south4 ,when the last of the glaciers melted from ,illinois1 about #ae1jjj years ago1 the country that emerged looked far different from the preglacial land4 ,old hills and valleys had vanished1 new ones had formed1 and a mantle of unconsolidated rock material1 the burden carried by the ice and dropped as the ice melted1 lay over most of the region4 ,most of this material1 called glacial drift1 was brought in by the ice during the last two of the four major periods of glaciation--the ,illinoian period #ajj1jjj to #aej1jjj years ago and the ,wisconsinan #e1jjj to #ej1jjj years ago4 ,the older drift introduced during the ,kansan and ,nebraskan glacial periods is almost entirely buried beneath the later drifts4 ,the glaciers covered all of ,illinois except the northwestern corner1 the southwestern edge along the ,mississippi ,river1 and extreme southern ,illinois1 as shown in figure #a4 ,in those areas the land is much as it was before the glaciers came4 ,in the glaciated portion of the state1 however1 the bedrock generally is covered by the rock debris the ice carried from as far away as ,canada4 ,as the fringes of the ice melted1 these loads of rock material were1 in some places1 dumped as ridges 7moraines7 which are the hills and mounds on the flat prairies of the present landscape4 ,such material also filled ancient river valleys1 but new valleys were cut by torrents of water released by the melting ice4 ,illustration3 ,figure #a--;,a mantle of glacial drift covers the bedrock in much of ,illinois4 ,,wisconsinan ,,glacial ,,drift ,,kansan ,,glacial ,,drift ,,illinoian ,,glacial ,,drift ,the glacial drift belongs to the youngest 7topmost layer7 of the major divisions of our rocks1 which geologists have named the ,pleistocene 7scientific name for ,ice ,age deposits74 ,most of the drift is an unsorted mixture of clay1 pebbles1 and boulders called 8till10 but some glacial deposits consist of water-sorted sand and gravel carried and deposited by meltwater from the glaciers4 ,other materials were deposited by the wind--sand was piled into shifting dunes and fine silts were spread like a blanket over the land4 ,this mantle of silt is called loess4 ,the glacial deposits contain a wide variety of rocks1 some brought from regions to the north1 others scoured from the layers of native rock in ,illinois4 ,the limits of the ,illinoian1 the ,wisconsinan1 and the ,kansan glaciations are shown in figure #a4 ,some of the more prominent moraines are sketched with dark gray lines on plate #a4 ,within this area1 glacial drift covers the bedrock except along valleys where streams have cut through and removed it4 ,,bedrock ,,geology ,beneath the glacial drift of ,illinois many layers of rocks overlie a base of ancient crystalline rocks that in ,illinois occur at depths of #b1jjj to as much as #ae1jjj feet4 ,the geologic map 7plate #a1 in pocket7 is drawn as if the mantle of glacial drift had been removed to expose the layers of bedrock1 which are largely limestone1 shale1 and sandstone4 ,the key on the map shows the age sequence of the rocks1 arranged with the youngest at the top1 and gives the names that geologists have assigned to the various systems of rocks4 ,each system consists of rocks that were deposited during a long period of time4 ,the complete sequence of rocks might be likened to a book of earth history1 and each system likened to a chapter4 ,systems are divided into formations1 which might be regarded as pages in the book4 ,as shown on the generalized rock column in figure #b1 the rocks next older than the glacial drift 7,pleistocene7 are the ,tertiary and ,cretaceous sands1 gravels1 and clays1 mostly unconsolidated4 ,they occur only at the extreme southern tip of ,illinois and were deposited when that area was covered by a northward extension of the ,gulf of ,mexico4 ,the ,tertiary rocks are shown on the map in grayed pink 7,t7 and the ,cretaceous in red-violet 7,k74 ,next older than the ,cretaceous are the ,pennsylvanian rocks1 named for the state of ,pennsylvania where they are well exposed and were first studied4 ,the ,pennsylvanian ,system is divided into two areas on the map 7,p and ,p74 ,the rocks shown in lightest gray 7,p7 lie above the ,no4 #f ,coal in the sequence and those in medium gray 7,p7 lie below it4 ,the ,no4 #f ,coal is one of the thickest1 most valuable coals in the state4 ,pennsylvanian rocks occur under the glacial drift1 and their thickness ranges from a few feet to as much as #c1jjj feet4 ,illustration3 ,figure #b--;,diagram of layers of rocks in ,illinois4 ,the oldest rocks are at the bottom1 the youngest at the top4 ,names are the standard ones applied by geologists to the subdivisions of the geologic eras4 ,era ,general ,types of ,rocks ,period or ,system and ,thickness ,epoch ,,cenozoic 8,recent ,life0 ,age of ,mammals ,quaternary #j-ejj ,pleistocene or ,glacial ,age ,recent--alluvium in river valleys ,glacial till1 glacial outwash1 gravel1 sand1 silt lake deposits of clay and silt1 loess and sand dunes2 covers nearly all of state except northwest corner and southern tip ,tertiary #j-ejj ,pliocene ,chert gravel2 present in northern1 southern1 and western ,illinois ,eocene ,mostly micaceous sand with some silt and clay2 present only in southern ,illinois ,paleocene ,mostly clay1 little sand2 present only in southern ,illinois ,,mesozoic 8,middle ,life0 ,age of ,reptiles ,cretaceous ,mostly sand1 some thin beds of clay and1 #j-cjj' locally1 gravel2 present only in southern ,illinois ,,paleozoic 8,ancient ,life0 ,age of ,amphibians and ,early ,plants ,pennsylvanian ,largely shale and sandstone with beds of coal1 #j-c1jjj limestone1 and clay 78,coal ,measures07 ,mississippian ,black and gray shale at base2 middle zone of #j-c1ejj' thick limestone that grades to siltstone1 chert1 and shale2 upper zone of interbedded sandstone1 shale and limestone ,age of ,fishes ,devonian ,thick limestone1 minor sandstones and shales2 #j-a1ejj' largely chert and cherty limestone in southern ,illinois ,age of ,invertebrates ,silurian ,principally dolomite and limestone #j-a1jjj' ,ordovician ,largely dolomite and limestone but contains #ejj-b1jjj' sandstone1 shale1 and siltstone formations ,cambrian ,chiefly sandstones with some dolomite and shale2 #a1ejj-c1jjj' exposed only in small areas in north-central ,illinois ,,archeozoic and ,,proterozoic ,igneous and metamorphic rocks2 known in ,illinois only from deep wells ,the ,pennsylvanian ,system contains many different kinds of rocks1 including all of our minable coals4 ,it also contains important deposits of limestone1 shale1 and clay1 and at places oil and gas4 ,next below the ,pennsylvanian are the rocks of the ,mississippian ,system1 shown in blue on the map 7,m and ,m74 ,the lower and middle ,mississippian rocks 7,m7 are largely limestone in and near the areas mapped1 but in the central and eastern part of the state where they are buried under ,pennsylvanian rocks they contain much siltstone and cherty limestone4 ,the upper ,mississippian rocks 7,m7 consist of a succession of sandstone1 shale1 and limestone formations4 ,this system of rocks takes its name from the ,mississippi ,river because there are excellent exposures of these strata along the ,mississippi ,valley in western ,illinois1 southeastern ,iowa1 and eastern ,missouri4 ,the ,mississippian rocks are a source of limestone1 fluorspar1 zinc1 and ganister1 and are of greatest economic significance in southeastern ,illinois where they are the most important of our oil-producing rocks4 ,the ,devonian 7,d1 dark gray on the map71 ,silurian1 7,s1 violet71 ,ordovician 7,o1 light pink71 and ,cambrian 7,c1 deep pink7 rocks1 in the order named1 are older than the ,mississippian strata4 ,in general1 they include dolomite1 limestone1 shale1 and sandstone4 ,except for small areas along the ,mississippi and ,illinois ,river ,valleys1 these older rocks are found at the surface only in the northern quarter of the state and locally in ,alexander1 ,hardin1 ,jackson1 ,monroe1 ,pike1 and ,union ,counties4 ,they are nevertheless economically important because they yield limestone1 dolomite1 silica sand1 oil1 zinc and lead1 tripoli1 novaculite1 and novaculite gravel4 ,the rocks of the ,cambrian through ,pennsylvanian ,systems belong to the ,paleozoic ,era4 ,the ,paleozoic rocks overlie crystalline rocks1 such as granites1 that extend to unknown depths in the crust of the earth4 ,the crystalline rocks are not exposed in ,illinois but are encountered in the drilling of some deep wells and may be seen in the nearby ,missouri ,ozarks and in central ,wisconsin4 ,,structural ,,geology ,the rock formations appear to lie flat in most of ,illinois1 but they are slightly inclined in most places4 ,in some areas they are down-warped into basins and troughs 7synclines71 upfolded into domes and arches 7anticlines71 or broken by faults4 ,the largest structural feature in ,illinois is a great spoon-shaped basin--the ,illinois ,basin--that extends southeastward into ,indiana and ,kentucky4 ,the deepest part of the basin is in southeastern ,illinois4 ,illustration3 ,figure #c--,when rocks are down-warped and the surface is leveled by erosion1 the youngest rocks are preserved in the center and the older rocks are exposed at the margins4 ,because the entire region1 including the basin1 has been eroded by rain1 ice1 wind1 and many rivers and streams1 the youngest ,paleozoic rocks 7top-most layers7 are preserved only in the middle of the basin1 as shown in figures #c1 #f1 and #g4 ,this is why the map shows the coal-bearing rocks of ,pennsylvanian age in the center of the state and the older rocks cropping out in successive bands around the margins of the basin in southern1 western1 and northern ,illinois4 ,distribution of bedrock in northern ,illinois is influenced by a broad upfold or arch 7see figures #d1 #f1 and #g74 ,the map 7plate #a7 shows the older rocks 7,cambrian and ,ordovician7 exposed at the center of the arch and surrounded by younger ,silurian and ,devonian rocks4 ,another elongated upfold 7anticlinal belt7 extends from the vicinity of ,dixon southeastward into ,indiana4 ,the crest of the upfold is indicated on the map by patches of ,silurian and ,devonian rocks in ,champaign and ,douglas ,counties4 ,illustration3 ,figure #d--,when rocks are upfolded and the surface is eroded1 the older rocks are exposed at the crest of the dome or anticline4 ,in extreme southern ,illinois and in north-central ,illinois1 the rock layers are broken by great faults 7see figures #e and #f7 which displace the layers of rocks by as little as a few inches to as much as #c1jjj feet4 ,the structural map of ,illinois 7figure #f7 shows the position of the major geologic structures4 ,the big basin is indicated by shading1 with the darkest pattern showing where the basin is deepest4 ,the same strata that lie at sea level at the basin's outer edge are downwarped to #f1jjj feet below sea level in its deepest part4 ,axes of some small anticlines and locations of major fault zones also are shown4 ,illustration3 ,figure #e--,when rocks are faulted by earth stresses1 the layers of rock are displaced or offset4 ,illustration3 ,figure #f--,major structural features of ,illinois--the ,illinois ,basin1 anticlines1 and faults4 ,the increasing depth of the basin is shown by progressively darker patterns4 ,,kankakee ,,arch ,,mississippi ,r4 ,,arch ,,la ,,salle ,,anticlinal ,,belt ,,ozark ,,uplift ,,key ,position of major anticline ,major faults ,illustration3 ,figure #g--,the cross section from north to south through ,illinois shows the strata down-warped into the basin4 ,,historical ,,geology ,reading the history of the earth's crust is like reading a mystery story4 ,the geologist must examine1 or read1 each rock layer1 from the youngest at the top to the oldest at the bottom1 searching for clues to its origin1 age1 and development from which he can reconstruct the past4 ,one of the clues to the past is the fossil remains of plants and animals found in the rocks4 ,for instance1 if a certain coral is known to have lived only during one span of time1 all rocks containing that coral fossil must have been formed within that span4 ,records of wells 7well logs7 and rock cores or samples collected when test holes are drilled into the bedrock also reveal much about the sequence of rock strata beneath the surface4 ,the kinds of rocks encountered tell1 in addition1 something about ancient geography1 for some were formed on land and others were deposited in long-departed seas4 ,such knowledge is extremely important in finding and developing mineral resources such as coal and oil4 ,,economic ,,geology ,minerals produced commercially in ,illinois include crude oil1 coal1 limestone1 dolomite1 clay1 sand1 gravel1 fluorspar1 tripoli1 ganister1 novaculite gravel1 silica sand1 and the metals zinc and lead4 ,the distribution of mineral industries1 shown in the several maps of figures #h through #ab1 is1 of course1 related to the distribution of the rocks 7plate #a74 ,for example1 the coal mines are scattered along the margin of the area of ,pennsylvanian rocks where the coals are at relatively shallow depths4 ,the mineral fuels1 coal and petroleum1 are the leading mineral products of ,illinois1 making up about #gj percent of the annual value of all minerals produced in the state4 ,for many years coal was at the top of the list1 but petroleum now holds first place4 ,petroleum ,in recent years production of petroleum has averaged about #gh million barrels each year1 making ,illinois the eighth largest petroleum producing state4 ,the major oil area is the deep part of the ,illinois ,basin in the southcentral and southeastern parts of the state1 but significant discoveries have been made recently in central and western ,illinois4 ,there are about #dij oil fields in ,illinois1 ranging from a few to several thousand acres in size4 ,oil has been discovered in rocks of the ,pennsylvanian1 ,mississippian1 ,devonian1 ,silurian1 and ,ordovician ,systems1 but the ,mississippian are the most productive and account for about #gf percent of our total oil production4 ,illustration3 ,figure #h--,oil pools in ,illinois as of ,january #a1 #aifa4 ,the pools are concentrated mainly in the ,illinois ,basin and along the ,la,salle ,anticlinal ,belt4 ,illustration3 ,figure #i--;,active coal mines are scattered around the margin of the basin where the coals are at relatively shallow depths4 ,,key ,,shipping ,,mines ,underground ,strip ,slope ,,local ,,mines ,,over #be1jjj ,,tons ,underground ,strip ,coal ,illinois ranks fourth in the nation among states that produce bituminous coal1 the type of coal most widely mined in the ,united ,states4 ,coal is used by many manufacturing industries1 by public utilities companies that burn coal to generate electricity1 and by individuals for heating homes4 ,all ,illinois coal deposits are found in the ,pennsylvanian ,system4 ,of the many coals1 only a few are thick enough to be mined profitably4 ,the coal is of bituminous rank1 but it varies in quality4 ,illinois coal reserves in strata more than #bh inches thick are estimated at #acg billion tons and are larger than those of any other state4 ,around the edge of the coal basin where the coal lies at shallow depths1 it is commonly mined in open pits 7strip mines74 ,however1 in the past1 most coal has been mined underground1 and more than half of ,illinois coal is still produced from such mines4 ,limestone and ,dolomite ,there are two types of carbonate rocks in ,illinois1 limestone and dolomite4 ,in appearance they are almost indistinguishable1 although they are different chemically4 ,limestone is composed mainly of calcium carbonate 7the mineral calcite71 whereas dolomite is calcium magnesium carbonate 7the mineral dolomite74 ,limestone deposits are found at many places in the western1 southwestern1 and southern marginal portions of the state4 ,they are largely of ,mississippian and ,ordovician age4 ,lesser deposits of ,pennsylvanian limestone are found in the central portion of the state4 ,in the northern fifth of the state1 dolomites of ,silurian and ,ordovician age are exposed at many places4 ,limestone and dolomite are quarried for a variety of uses1 including aggregate for concrete1 agricultural limestone1 railroad ballast1 chips for bituminous roads1 and for use in metallurgical and chemical processes4 ,they also are quarried for building stone at some places1 and marble is produced in southern ,illinois4 ,illustration3 ,figure #aj--,limestone and dolomite are quarried at many places1 but fluorspar1 zinc1 and lead are produced in restricted mineralized areas4 ,,key ,quarry1 ,limestone or ,dolomite ,cement or ,lime ,fluorspar ,zinc and ,lead ,limestone and shale or clay are burned together in kilns to produce portland cement4 ,portland cement is manufactured from a ,pennsylvanian limestone in ,la,salle ,county and from an ,ordovician limestone in ,lee ,county4 ,limestone or dolomite also is burned in kilns to make lime4 ,mississippian limestone is used in ,adams ,county and ,silurian dolomite is used in ,cook ,county for lime making4 ,clay and ,clay ,products ,illinois commercial clays are found in glacial1 ,cretaceous1 ,tertiary1 and ,pennsylvanian deposits4 ,pennsylvanian shales also are sources of clays4 ,glacial clays1 which occur as loess 7wind-blown materials71 alluvial 7water-deposited7 sediments1 and glacial till1 are widespread in the state4 ,cretaceous and ,tertiary clays1 at the extreme southern tip of the state1 are valuable for the manufacture of heat-resistant bricks and coatings and for floor-sweeping compounds4 ,pennsylvanian clays and shales are the most important source of clay for manufacturing such products as pottery1 stoneware1 drain tile1 sewer pipe1 flue tile1 building tile1 brick1 and special heat-resistant fire-brick4 ,sand and ,gravel ,deposits of sand and gravel1 found in many parts of ,illinois1 provide large quantities of material for concrete1 railroad ballast1 road gravel1 building sand1 molding sand1 and other uses4 ,glacial deposits are the principal sources of sand and gravel1 but in extreme southern ,illinois where there is no glacial drift the main source of supply is ,tertiary gravel and ,devonian chert gravel4 ,illustration3 ,figure #aa--,the clay industry is scattered widely in ,illinois4 ,many manufacturing plants are located at the clay pits4 ,,key ,pit or ,plant ,almost every county has some sand and gravel1 but the major areas of production are northeastern ,illinois and some of the major rivers4 ,considerable tonnages of sand and gravel are dredged from bars in the channels of the ,mississippi1 ,ohio1 and ,wabash ,rivers4 ,silica ,sand ,silica sand is used in making glass1 for sand blasting1 as grinding sand1 as molding sand for casting steel1 and in the fracture treatment of oil wells to increase oil production4 ,some of the sand is finely pulverized into a powder that is used as a filler1 a fine abrasive1 as a ceramic material1 and for many other purposes4 ,this special sand1 composed of grains of the mineral quartz 7silica71 comes from a sandstone of ,ordovician age that is mined in ,la,salle and ,ogle ,counties4 ,tripoli and ,ganister ,tripoli1 or 8amorphous0 silica1 is mined from ,devonian rocks in ,alexander ,county4 ,the silica is finely ground for use as a polishing agent1 as a filler1 in buffing compounds1 and for other purposes4 ,ganister1 a granular material with a high silica content1 also is mined in extreme southern ,illinois4 ,it is used in making products that can withstand high temperatures4 ,fluorspar ,for many years ,illinois has led the nation in the production of fluorspar1 accounting annually for about half the total ,united ,states output4 ,the industry is centered in ,hardin and ,pope ,counties where the deposits occur in veins and beds in rocks of the ,mississippian ,system4 ,reserves of fluorspar are adequate to supply the industry for many years4 ,illustration3 ,figure #ab--,sand and gravel is produced at many places in the state4 ,silica sand is produced only from a sandstone in northern ,illinois4 ,tripoli is found only in southern ,illinois4 ,,key ,sand and ,gravel ,silica ,sand ,molding ,sand ,tripoli ,fluorspar is used in the manufacture of hydrofluoric acid1 as a flux in the manufacture of steel1 in the refining of aluminum1 for the manufacture of fluorine compounds used in a variety of products1 in ceramic glazes1 and for other special purposes4 ,lead and ,zinc ,lead and zinc are the only metallic minerals mined in ,illinois4 ,deposits are found in ,jo ,daviess ,county in northwestern ,illinois and in the fluorspar area of ,hardin and ,pope ,counties in extreme southern ,illinois4 ,in northwestern ,illinois the ore occurs in rocks of ,ordovician age1 but in southeastern ,illinois it is associated with fluorspar in rocks of ,mississippian age4 ,between #ahbj and #ahfe1 the mining area of which northwestern ,illinois is a part was the nation's principal producer of lead ore4 ,in recent years production of zinc has increased and that of lead has decreased4 ,water ,supplies ,water1 too1 is a mineral resource1 and our most necessary one4 ,the source of nearly all water is rain and snow1 which collect in lakes and streams or seep into the ground to form our two types of water supplies--surface water and ground water4 ,ground water in ,illinois collects underground in deposits of sand and gravel or in the porous sandstone or limestone layers of bedrock4 ,these rock materials are called 8aquifers0 because of their ability to hold water and to allow it to flow into wells that are drilled into them4 ,the aquifers are not equally distributed throughout ,illinois1 so ground-water supplies are abundant in some parts of the state but are scarce in others4 ,some ,illinois cities depend wholly or partly on surface supplies from lakes and rivers4 ,the sand and gravel aquifers yield more ground water than any others in ,illinois4 ,the major sand and gravel aquifers were deposited by streams and lie along river valleys4 ,some of these river valleys are no longer visible to us because they were buried by glacial drift4 ,they are recognized1 however1 from well records or drilling records4 ,the northern third of ,illinois has the most abundant supplies of ground water4 ,bedrock formations of ,devonian through ,cambrian age are favorable aquifers and supply drinkable 7potable7 water at depths of from #bjj to #b1jjj feet4 ,these formations1 however1 lie much deeper in the ,illinois ,basin1 where the water they furnish is too salty for most uses4 ,west of the ,illinois ,river and at the southern tip of the state1 the ,mississippian1 ,devonian1 and ,silurian limestones are the chief aquifers4 ,their yield1 however1 is small4 ,in the ,illinois ,basin all these formations are overlain by ,pennsylvanian rocks which offer only small1 scattered supplies of ground water4 ,,illinois ,,state ,,geological ,,survey ,a city or farmer needs a new water supply4 ,where can suitable water-bearing formations be found8 ,a new limestone quarry is considered4 ,where are the most suitable limestone deposits8 ,a coal mine is being planned4 ,how deep must a shaft be sunk to reach the nearest minable coal and what will the mining conditions be8 ,a land owner has a clay deposit on his land4 ,what uses can be made of it8 ,a road is to be constructed4 ,are sand and gravel or limestone deposits available nearby for construction materials8 ,a farmer wants to know whether there might be oil on his property4 ,are oil-bearing structures present and1 if so1 at what depth8 ,these are typical questions brought to the ,illinois ,state ,geological ,survey by the industries and people of ,illinois4 ,from its accumulated store of information and experience1 the ,survey provides answers4 ,this storehouse of knowledge is the result of the ,survey's continuous program of geologic exploration1 mapping1 research1 and organization and interpretation of data4 ,the ,survey explores and maps the geology and mineral resources of the state1 does research to find new and improved uses for our mineral resources1 and organizes and interprets basic geologic information gathered from well logs1 rock samples1 and field studies1 putting them all into usable form4 ,such knowledge is shared with the public through publications1 maps1 lectures1 and personal consultations with industries1 drillers1 engineers1 land owners1 teachers1 and others in need of geologic information4 ,the discovery of facts about the rich mineral resources of ,illinois has1 in effect1 only begun1 and it is the task of the ,geological ,survey to continue to collect and apply new information so that our resources can be used to the best advantage4 ,,educational ,,extension ,,program ,the ,educational ,extension ,section of the ,geological ,survey conducts six field trips each year1 in various parts of the state1 for teachers1 students1 and laymen4 ,it also assembles and distributes rock and mineral collections for ,illinois educational groups1 gives lectures1 prepares exhibits1 and identifies rocks and minerals for the public4 ,educational ,extension publications1 such as this book1 are simplified discussions of geological subjects4 ,available for #be cents each1 these include3 ,educational ,series #d3 ,guide for ,beginning ,fossil ,hunters1 by ,charles ,w4 ,collinson4 ,educational ,series #e3 ,guide to ,rocks and ,minerals of ,illinois4 ,educational ,series #f3 ,field ,book of ,pennsylvanian ,plant ,fossils of ,illinois1 by ,charles ,collinson and ,romayne ,skartvedt4 ,many technical discussions of the various phases of ,illinois geology also are published by the ,geological ,survey4 ,regional reports on the geology and mineral resources of some areas are available in many school and public libraries or they may be purchased from the ,survey4 ,some of the regional reports include3 ,beardstown1 ,glasford1 ,havana1 and ,vermont ,quadrangles1 ,bulletin #hb1 #a4jj4 ,buda ,quadrangle1 ,circular #bge1 no charge4 ,carlinville ,quadrangle1 ,bulletin #gg1 #a4jj ,chicago ,region1 ,bulletin #fe1 ,part #a1 #ej cents4 ,marseilles1 ,ottawa1 and ,streator ,quadrangles1 ,bulletin #ff1 #a4jj4 8,mineral ,production in ,illinois in #aiei10 ,circular #cjj 7no charge71 is one of a series of annual economic summaries4 8,caves of ,illinois10 ,report of ,investigations #bae1 price #ej cents1 will be available by ,september #aifa4 ,illinois ,state ,geological ,survey ,educational ,series #g #bd pages1 #a plate1 #ab figures1 #aifa ,illustration3 ,illinois ,state ,geological ,survey1 ,urbana ,educational ,series #g--,plate #a--,north ,illustration3 ,illinois ,state ,geological ,survey1 ,urbana ,educational ,series #g--,plate #a--;,central ,illustration3 ,illinois ,state ,geological ,survey1 ,urbana ,educational ,series #g--,plate #a--,south ,,geologic ,,map ,,of ,,illinois showing ,,bedrock ,,below ,,the ,,glacial ,,drift #aifa ,,key ,t ,tertiary 7,pliocene omitted7 ,k ,cretaceous ,p ,pennsylvanian 7,above ,no4 #f ,coal7 ,p ,pennsylvanian 7,below ,no4 #f ,coal7 ,p ,pennsylvanian 7,above ,no4 #f ,coal7 ,m ,mississippian 7,upper7 ,m ,mississippian 7,middle and ,lower7 ,d ,devonian ,,sd ,silurian and ,devonian ,s ,silurian ,o ,ordovician ,c ,cambrian ,f ,fault ,,osdm ,complex faulted area ,physiographic base map by ,james ,a4 ,bier ,price1 #be cents ,illustration3 ,,pennsylvanian ,,coal-,,bearing ,,rocks ,transcriber's ,notes --,silently corrected a few typos4 --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,in the text versions only1 text in italics is delimited by underscores4