last (Vashon) glaciation of the Puget Lowland
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.
global sea level
ice advance and retreat
isostatic depression and rebound
initial topography (a fiction!)
Ralph A. Haugerud -USGS