1. Geologic map and distribution of heavy minerals in Tertiary and uppermost Cretaceous rocks of the Douglas 30ʹ x 60ʹ quadrangle, Converse and Platte counties, Wyoming Yale Public content 1990. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Wyoming, Converse County, and Platte County.