GEOHERITAGE AND COLLECTIONS

Historical fossil, rock, or mineral collections are an important but sometimes overlooked component in geoheritage studies. These collections are frequently essential in documenting the historical role of geology in the early exploration, development, and scientific study of these sites. Moreover, the localities that produced these specimens often no longer exist owing to urban and regional development, thereby eliminating the opportunity to acquire additional material for new research programs. This is especially true in heavily developed eastern and central United States areas. Here natural bedrock exposures tend to be rare and small in contrast with mountainous or undeveloped areas of the west. The Chicago and Milwaukee metropolitan regions of the central United States are key examples of the importance of historical collections of this nature. Through the 19^th and early 20^th centuries, quarrying and mining produced many temporary rock exposures, providing construction resources such as Milwaukee Cement or energy resources such as coal, essential for local development and opportunities for scientific research. At some of these manmade rock exposures, important scientific discoveries were made, including the discovery of the first known early Paleozoic (Silurian) reefs and the documentation of the world-famous Carboniferous Mazon Creek Biota. Since the mid-20th century, however, most stone quarries and coal mines have closed, limiting the further study of the local geology and the assembly of new paleontological collections. Surviving examples of important geoheritage collections from this region are the Thomas A. Greene and F. H. Day collections. The Greene collection was assembled by a 19^th-century Milwaukee businessman. It features the most extensive collection of Milwaukee-Chicago Silurian reef fossils and a substantial collection of the Devonian Milwaukee Formation biota. Well documented with extensive original correspondence, it demonstrates how 19^th-century amateur naturists assembled their collections and their role in scientific discovery. The Day collection, made by a contemporary Wauwatosa physician, consists of Wisconsin Silurian reef fossils assembled from now-inaccessible localities that were critical in identifying these ancient ecosystems.