The Troutdale Formation was named by Hodge (1938) for thick beds of gravels and sands exposed as cliffs along the Sandy River near the town of Troutdale, Oregon.
Sandy River (Oregon) (Wikipedia) The Sandy River is a 56-mile (90 km) tributary of the Columbia River in northwestern Oregon in the United States. The Sandy joins the Columbia about 14 miles (23 km) upstream of Portland.
