1. Map showing depth to bedrock of the Tacoma and part of the Centralia 30ʹ x 60ʹ quadrangles, Washington Yale Public content 1994. 2002-06-01T04:00:00Z. 2002-06-01T04:00:00Z. Geological Survey (U.S.). The Survey ; For sale by Map Distribution. English. Public. Washington (State) and Puget Sound Region.