Example of Vashon drift at Duck Bay
A layer of silty clay, gravel, and boulders that was deposited on the West Coast when the Fraser Glaciation melted 13,000 years ago. Those huge boulders you see on Savary's beaches are visible examples of it.
1. "The Fraser Glaciation began about 25,000 BP and lasted until the glaciers retreated for a final time between 13,000 and 11,000 years ago.
As the ice melted, rock debris and sediments dropped out as a discontinuous and variable-depth layer of till (Vashon Drift)[over] the island. … Bornhold et al. (1996) note that most of the boulders and gravel found on the beaches are derived from eroding layers of Vashon Drift.
The Vashon Drift layer is quite extensive through DL 1375, with the greatest depths occurring under the dunes on the western side of the property."
(Source: Dunster, 2000)