SOUTHERN ILLINOIS GEOLOGY
CIVILIZATION BASED ON GEOLOGY—GENERAL SCIENTIFIC PHASE—THE GEOLOGICAL ERAS—TABLE OF GEOLOGICAL TIME DIVISIONS-THE GLACIAL PERIOD
CIVILIZATION BASED ON GEOLOGY“It is axiom in general application in geological science that there is an intimate relation existing between the physical geography and the geological history of every portion of the earth ‘s surface; and in all cases the topographical features of a country are moulded by, and therefore must be, to some extent at least, a reflection of its geological structure. . . . More over, all the varied conditions of the soil and its productive capacities, which may be observed in different portions of our state, are traceable to causes existing in the geological history of that particular region, and to the surface agencies which have served to modify the whole, and prepare the earth for the reception and sustenance of the existing races of beings. Hence we see the geological history of a country determines its agricultural capacities, and also the amount of population which it may sustain, and the general avocation of its inhabitants.” The people of Arabia could not well be other than horsemen, herdsmen, and dwellers in tents. It was altogether fitting that the shepherds of Judea should have been watching their flocks by night. What else could the early people of New England do so well as to fish for their living? It is no mystery that Southern Illinois should count among her population tens of thousands of native and foreign-born miners. How appropriate that central Illinois should raise corn, and hay and oats. It is as easy to explain why the people of western Dakota, Nebraska, Kansas, Oklahoma, and Texas should lead the life of the plainsman as to explain why the Scotch are a frugal, healthful, God-fearing people. Reverting once more to the principle that things are known only in their relation, we may readily understand that the life of any people as a whole may be interpreted in a very large degree in terms of the geological structure of the region where that people lives. It is true that the casual observer may see that the people of central Illinois are agriculturalists because the lands are adapted to that occupation: Or that the people of the Rocky mountains are largely miners because there are many precious minerals in that region. But this understanding of these things is superficial and not in any sense scientific and hence not satisfying. He fails to see the vital relation between the particular calling a people may have and the peculiar geological formation of the region which lies at the base of that calling. The fundamental, scientific explanation of a people’s occupation is wrapped up in the geology of that people’s land. Nor does the geological history explain only the kind of occupation a people may follow; but the social, intellectual, and spiritual life derives its character indirectly from the rocks, the hills, and the streams, or perchance from the presence of the great ocean. It is generally agreed that the explanation of the wonderful genius of the old Greek civilization was partly accounted for by the great number of physical units in mountains and valleys. The Greeks never attained to a great national life; the geological facts were against such attainment. But what the Greeks lost in government and national political p. 3 life, they were more than compensated for in their enriched intellectual and spiritual life. Nowhere has beauty had such exponents as in Greece. Nowhere has the spirit of moderation been so wonderfully manifest. The wonderful language of the Greeks, their unparalleled sense of the beautiful, their charming spirit of moderation—may they not all be accounted for in the great variety of landscape, the well proportioned hills, the flowing valleys, the alternation of land and water? Be it so.
GEOLOGY (GENERAL SCIENTIFIC PHASE)Geology is a science which has for its purpose the revelation of the processes by which the outer portion, or crust of earth, was brought to its present state or condition. It does not attempt to account for the origin of matter, but assumes that the earth once “existed in a state of fusion,” or in other words, that the earth was a globe of liquid fire. The radiation of heat from the surface resulted in the gradual cooling of the mass, and thus the first rocks were formed, just as rocks are now formed from molten masses that are poured forth from some of our great volcanoes. It is the theory then that the outer surface of the earth was once a great mass of rock formed from the cooling of the outer portions of the liquid sphere. This outer crust became hard while the inner part of the earth was still in a molten condition. This hard crust of the earth formed from the cooled outer portions of the liquid mass is called igneous rock. As the cooling process continued, the layer of rock became thicker by the additions of inner portions, and the liquid mass has constantly decreased in size. As time went on the enclosing crust “crumpled” in its effort to conform to the liquid mass beneath. In the course of time water gathered in the depressions and the projecting portions became our continents. Eventually the elevated portions began to disintegrate under the influence of rain and other agencies, and the detritus was transported by running water and deposited in the lower levels, In the course of great stretches of time these deposits, which necessarily were in layer form, grew in numbers until they now aggregate thousands of feet in thickness. These layers of rock formed under standing water are known as sedimentary, or stratified rocks. We thus have two general classes of rock, igneous or fire rock, and sedimentary or layer rock. Great convulsions of the earth have completely changed the original relation of these two kinds of rock. The igneous elevations have been worn down and in many instances have sunken under the sea, and the sedimentary areas have been upheaved and have produced our present continental forms. In such cases the sedimentary rocks are no longer lying horizontal as they were when first formed, but are found in all kinds of positions. In some instances the layers may be seen standing on edge. Again the upheaving force may have been less violent, and the layers may have been pushed up in long folds; a cross section of which would present a series of arches. A third form of upheaval resulted in pushing large areas straight up, the elevated area breaking loose from the surrounding areas thus presenting the fractured edges to view many hundreds of feet above the surrounding country. p. 4
It must not be thought that there was much regularity in the original formation of the sedimentary layers. For these layers are not uniform in thickness, nor in extent. Often a layer will appear in one place while in large areas of adjacent territory that layer will not appear. This is accounted for by supposing that there were slight upheavals which pushed the given territory up while the surrounding areas were receiving other layer material. If a certain deposit was begun upon a foundation which was slightly inclined and the deposit continued for long periods, that layer would be thick on one side of the area and thin upon the other, even thinning to an edge.These layers have all been studied and named, their life history written, and their relationships established. The individual layers have been brought into “groups” and named from the condition of life represented in the various layers. The time occupied in depositing the layers in any named group, is sometimes spoken of as an era, while the subdivisions of an era are known as periods. A brief description of the eras will enable the reader to follow the descriptive matter with greater ease.
THE GEOLOGICAL ERAS
The Archeozoic Era includes the oldest stratified rocks, and these under ordinary circumstances would be found just above the oldest igneous formation. The word Archeozoic means beginning—that is the beginning of life. However, few life remains have been found in the layers of this era. So uncertain are the geologists about the identity of life forms in this era that the word Azoic, which means without life, has been applied. The rocks of the Archeozoic Era are so interwoven with the igneous rocks that there is great confusion in the layers, and much uncertainty in identification obtains.The Proterozoic Era rests directly on top of the archeozoic layers. The stratifications are much more easily determined in this era. Little if any signs of animal or plant life are to be found in these rocks and the term Azoic is also applied here. The Paleozoic Era is the third in order, and lies directly above the Proterozoic. The word means ancient life—that is first life. The oldest forms of life appear in the rocks of this era. Since they are the oldest forms they would be by the evolutionary theory the lowest forms when structure is considered. Something like five hundred species of the fauna have been classified belonging mostly to the invertebrates. Some plant life is also recognized. The Mesozoic Era is fourth in order and lies just above the Paleozoie Era. The rocks of this group are so named because of the advanced stage of life represented, the word Mesozoic meaning middle life—that is life between the invertebrates and the higher forms of vertebrate life. The life found includes reptiles, amphibians, and mollusks, as well as the lowest forms of mammals, fishes, and birds. And lastly we have the Cenozoic Era. The word means modern life or new life. This is the age of mammals. There now appears the fullest development of animal life including man. The poisonous gases have disappeared—largely consumed by the abundant growth of vegetation. The earth, and water, and air have become the fit habitation of the highest forms of fishes, birds, and mammals. This is the age in which we now live. p. 5
TABLE OF GEOLOGIC TIME DIVISIONS
GEOLOGY OF SOUTHERN ILLINOIS
THE GLACIAL PERIOD
The Cenozoic Era is so recent and its history is so vitally related to the life of the human race that it will be quite proper to give a p. 8 more extended account of the geological story of this period. The formations are discussed under the Tertiary and Quaternary Periods. The latter period is popularly divided into the Glacial and the PostGlacial formations. These glacial formations have been so recent and the territory covered by the great ice sheets so extensive, that great interest attaches to this period.In North America there seems to have been three great centers of glacial movement—one known as the Labrador ice sheet; a second called the Kewatin ice sheet; and the third the Cordilleran ice sheet. The first sheet had its center of movement near the central point of the peninsula of Labrador; the second had its center near the western shore of Hudson Bay; and the third moved from the Canadian Rockies. The ice sheet whose center rested on the Labrador peninsula is the one we are locally interested in. The movement from this center to the south, northeast and northwest soon reached the waters of the Atlantic and the Hudson Bay; but the movement to the southwest covered nearly the entire state of Illinois. The Labradorean sheet reached its extreme southern limit in Southern Illinois, some 1,600 miles from the point of departure. The advancing front in Illinois took on the form of a crescent and its extreme southern reach may be traced according to the most recent geologic surveys from Chester in Randolph county southeast through the southern side of Jackson, eastward through southern Williamson, east and northeast through southeastern Saline, northeastward to the Wabash through the northwest corner of Gallatin and southeastern White. This line marks the southern limit also of the prairie areas and is also coincident with the northern foot hills of the “Ozark Mountains” which trend east and west across the state through Union, Johnson, Pope, and Hardin. Illinois was subject to at least four ice-sheet invasions according to the more recent investigations. These in order of time were: First, the Illinois sheet, which seems to have covered nearly the entire state. The portions not covered are known as the driftless or unglaciated areas. There are three of these—First, all the territory south of the southern end of the drift as traced above from Chester to the Wabash. This driftless or unglaciated region includes in part the counties of Jackson, Williamson, Saline, Gallatin, and White, and it includes in whole the counties of Union, Johnson, Pope, Hardin, Alexander, Pulaski and Massac. There is a second driftless area of a few counties in the extreme northwest corner of the state in the vicinity of the old lead mines. The third driftless area is found in the end of the peninsula formed by the Illinois and the Mississippi rivers including the counties of Pike and Calhoun. The second invasion is known as the Iowan sheet. It seems not definitely settled whether this sheet had its origin in the Labrador center or in the Hudson Bay vicinity. It seems to have moved southeastward and left a “profusion of large granatoid boulders which lie chiefly on the surface and are somewhat aggregated into a boulder belt on the eastern border of the tract.” One may see residences and other buildings, yard fences and ornamental structures constructed from these boulders in the towns near the boulder field. Such houses may be seen in the county of DeKalb and adjoining counties. The territory covered by this second invasion may be roughly enclosed by the Rock river on the west, Wisconsin on the north, Lake Michigan p. 9 on the east, and on the south by the parallel of the southerly bend of Lake Michigan. The Third invasion is named the Earlier Wisconsin and covers the northeastern fourth of the state. The Fourth invasion is known as the Later Wisconsin and borders the west shore of Lake Michigan, reaching out some fifty or sixty miles from that body of water. Here in Southern Illinois we are more interested in the first ice sheet since it is the only one that directly affects us. No other single agent has been so potent in the modification of the surface of the earth as have glaciers and ice sheets. When we remember that these ice-sheets were hundreds and possibly thousands of feet thick, and were hundreds of miles in width and length, some adequate notion may be formed of their power to plow up and completely change the surface structure of the earth. The debris which they brought with them from the Laurentian mountains of Canada was distributed over Illinois greatly to the enrichment of the soils of our entire state. This material which eventually became our soil in all the glaciated areas, was transported in several ways. Much of it was pushed along mechanically in front of the advancing ice-sheet, so that when the forward movement began slowing up this material was left scattered along in lines agreeing in general with the front of the advancing ice-sheet. Much material was carried along under the ice-sheet and was very generally ground and distributed over the glaciated area.. Other material was carried on the ice-sheet and often deeply imbedded in it. When the movement was checked this superimposed material becoming heated under the warm rays of the sun worked its way through the ice and rested on the ground, the whole body of ice eventually melting. Lastly. Vast quantities of material were carried by the streams which continually flowed from the melting ice. Much of this detritus was left on the broad flat prairies, but much was carried into the streams which overflowing their banks carried this material to right and left in the stream’s valley where it was deposited as alluvium, previously mentioned. The material which these glaciers brought into our state is called Drift. Its composition varies, but is usually clay, sand, and boulders. This drift is often found stratified, but more generally it is without definite layer formation. Further attention will be given to this matter under the head of soils. We come now to the last phase of the geology—the Human or Present Period. We must now see the earth as the home of man. Through untold ages the Creator has been gradually unfolding his plan to us, of filling the earth with plants, and animals, and last and most important of all—man. It must not be supposed that the forces which have been operating through all the geological ages have all run their courses and are no longer active and powerful. Many of these forces which were instrumental in producing the various stages in the geological history are still at work and will continue to work for untold ages. Among these we may mention the forces affecting the elevation and subsidence of the continental forms. The work done by running water has not ceased as we can easily see everywhere. The disintegrating power of alternations in heat and cold especially when accompanied by the presence of moisture is always going on. We will now turn our attention to the resources which a wise Creator has placed within the reach of the human race.
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