Fossiliferous Cherts of the Midwest: Their Origin, Composition, and Prehistoric Use

Introduction Collectors and those involved in studying prehistoric Indian artifacts have almost certainly encountered remnants of fossils, both fragmentary and complete, preserved in the chert or flint of knives, blades, projectile points, scrapers and similar items. These fragments can resemble a variety of shapes, such as a circular or round minidonut-like appearance, thin narrow linear fragments, a line of tiny dots, fragments having a cluster of tiny holes or pores, and others. The well known Harrodsburg chert from Kentucky is an outstanding example of a silicified "fossil hash" composed of broken fragments from a variety of former marine organisms. How did the Harrodsburg and similar fossiliferous cherts form and what kinds of fossil fragments are represented? Geologically, how old are these fossiliferous cherts and in what environment and what processes led to their formation? What kinds of fossil organisms comprise the bulk of these cherts and where and how did they live? What specific fossiliferous cherts were utilized by prehistoric cultures and how did they use them? Were fossils themselves used by prehistoric people for specific purposes? The aim of this paper is to answer these and related questions without getting bogged down in detailed geochemical information. Since the author is most familiar with the fossil record, geologic history and chert (and flint) varieties of Ohio, Indiana, and Kentucky, the focus of this paper will concern this region.