
	The last (Vashon) glaciation of the Puget Lowland Inputs: global sea level ice advance and retreat isostatic depression and rebound initial topography (a fiction!) Ice advance and retreat were rapid. Seattle was covered by ice for less than 2,000 years. At glacial maximum about 1 km (3,000 ft) of ice covered Seattle. glacier fresh water salt water Ralph A. Haugerud -USGS