1. Map of bedrock geologic data sites, Glacier Peak Wilderness study, Chelan, Skagit, and Snohomish Counties, Washington [cartographic material] Yale Public content 1983. 2002-06-01T04:00:00Z. 2023-06-24T03:04:30Z. Geological Survey (U.S.). U.S. Geological Survey. English. cartographic image. Public. Washington (State) and Glacier Peak Wilderness Area.