An Introduction to the Geology of Parke County, Indiana

Parke County, which is located about 50 miles west of Indianapolis, has an area of 447 square miles. It is bounded on the north by Fountain County, on the northeast by Montgomery County, on the east by Putnam County, on the south by Clay and Vigo Counties, and on the west by Vermillion County. This publication provides a summary of the glacial and bedrock geology of Parke County, Indiana, including information on landforms, bedrock geology and mineral resources. Landscape features are natural phenomena which long have attracted man\u27s attention. Fr.equent reference to the permanence of mountains has been made in literature, even though the surface feature s of the earth actually have been modified continuously by water, ice, and winds. Geologic processes change the face of the earth an insignificant amount during a human lifetime, but if allowed to continue for thousands or millions of years, reduce mountains to nearly level plains. Because the surface features of the earth have changed so slowly during human history, little thought was given to a possible origin for them until the early part of the nineteenth century. Thus only a little more than a century ago scientists came to realize that the present surface of the earth has been formed by slowly acting agents throughout an immense span of time. Most of the landscape features of the earth have been sculptured by running water. The water that rushes down a bare-hillslope during a heavy rain erodes gullies in the soil. Soil particles that are removed in this way then are carried in suspension by rivers to a lake or an ocean where they are deposited as sediments of sands, muds, and oozes. As new material settles on top of the muds that already have been deposited, the older sediments are compressed and eventually become sandstones, mudstones, shales, and limestones. If the earth\u27s crust had never undergone any deformation, all the sediments which had accwnulated beneath ocean waters still would be under water. Large portions of the continents, however, have been intermittently exposed and submerged. Therefore, in places where these former sea floors now are dry land, the rocks that were deposited at a time when the land was covered by water can be studied, and some of the rocks which contain materials of use to man can be quarried or mined. If the rocks that underlie the earth\u27s crust were exposed everywhere, a geologist could trace rather easily any formation or stratum from one place to another. The rocks are not exposed in allplaces, however; in fact, in manyplaces outcrops are scarce. Thus the only reliable method by which rocks of a particular age can be identified from place to place is by their organic fossil content. The organisms which live during any geologic period are not like those of any other period because they undergo gradual change. Therefore, fos sils furnish a record, even though fragmentary, of the evolution of life