1. Geologic map showing distribution of clinker in the tertiary Fort Union and Wasatch formations, northern Powder River Basin, Montana Yale Public content 1993. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Powder River Basin (Wyo. and Mont.), Fort Union Formation, and Wasatch Formation.