Indiana Geology as it Influences Engineering Projects

The modern philosophy of the science of geology is based on the theory that “the present is the key to the past.” That is to say, the processes operating to modify the crust of the earth today have operated in much the same manner for countless ages. Thus by observing these processes and their incremental results, we may reconstruct the earth’s history from similar but accumulated results. These accumulated results are the materials that surround us, the rocks and the soils, their shape and character. Their content and arrangement bear witness to the patterns of ancient lands and seas, mountains and valleys, deserts and frozen waste lands. No modern trained geologist doubts the plausi­ bility of this thesis. Conversely, in applying the science to utilitarian ends it may be pointed out that “the past is the key to the present.” The past events, which have shaped the land and formed its underpinnings, are respon­ sible for our present environmental and economic situations. In the field of engineering alone we can find this maxim illustrated over and over again. For example, what lies behind the fact that unbroken road alignments are readily obtainable in northern Indiana whereas in the southern part of the state tremendous cuts and fills are often required, adding to the expense of construction? Why does one rock bed in Indiana produce material suitable for aggregate whereas others of seemingly similar character yield material which is deleterious when put to the same use ? Why do water supplies obtained from some wells seem limitless and consistent in purity while those of others are undependable and often need excessive treatment? These and many another engineer’s headache are intimately related to the past history of the earth. By delineating the areas of influence exerted by various periods of geologic time, similarity of conditions are