This shoreline stretch on the Salish Sea is nearly all boulders. Most of the boulders matched the local bedrock geology, but there are plenty of exotic boulders from far away places brought by the ice age glacier.
The source of the boulders is a glacial drift deposit along bluff above the beach.
Glacial drift with some stratification
Glacial drift directly deposited on bedrock
The shore has enough wave energy to removed the silt, sand and gravel from the beach leaving behind a lag of boulders. The headlands at bot ends of the beach were bedrock points. Any sand and small gravel had been transported into deep water off the points and outward from the boulder lag beach.