GIS APPLICATION OF THE NEWLY DIGITIZED USGS-DENVER CRETACEOUS FOSSIL MOLLUSK COLLECTION

Computer databases and GIS have revolutionized the way georeferenced data is stored, queried, analyzed, and graphically presented. We recently digitized the USGS Denver Cretaceous fossil mollusk collection. The collection has three primary components: 1) Core collection (approximately 14,000 localities) represents the fieldwork career of Dr. Cobban, his colleagues as well as specimens submitted from outside the Survey. The focus of this collection is the North American Cretaceous interior seaway. 2) A subset (approximately 1,000 localities) of fossil mollusks from historically early USGS Washington collections. 3) The Conlin collection, which was acquired from Texas cartographer James P. Conlin, (approximately 4,000 specimens), is perhaps the finest collection of North American Gulf ammonites. Our first GIS application of the data was on behalf of the USGS Rio Grande Basins Project. We converted locality coordinates from the standard township/range format to decimal degrees utilizing mathematical algorithms and topographical maps. This enables GIS software to import and portray the spatial distribution of sample sites within the Mancos Shale of Santa Fe County, New Mexico. The distribution of fossil localities was used to generate a map that delineates the Cretaceous seaway in Santa Fe County during the Upper Cretaceous Cenomanian through Campanian Stages.