Glacial erratic boulders of the Puget Sound region

Many glacial erratic boulders (often simply called glacial erratics) can be found in the Puget Sound region as far south as the Yelm area where the Puget Lobe of the glacier reached its maximum extent. The Pleistocene ice age glaciation of Puget Sound created many of the geographical features of the region, including Puget Sound itself, and the erratics are one of the remnants of that age.