Upper Eocene to Oligocene(?) rocks of the Ashford area, southern Cascades, Washington, include terrestrial sedimentary types derived from plutonic and metamorphic sources and dominantly andesitic volcanic flows and volcaniclastics. The sedimentary rocks crop out along the Nisqually River near Mount Rainier National Park and intertongue with andesitic volcanic rocks. At least 10,000 feet of andesite, basalt, and dacite, chiefly in the form of volcanic breccia, conglomerate, sandstone, and shale, with some thick flow units, overlies the sedimentary rocks of the Nisqually River. This series is lithologically divisible into lower, middle, and upper parts.

The sedimentary rocks are lithologically similar to those in the Puget group, and the volcanic rocks to those in the Keechelus andesitic series, but correlations are uncertain. New formational names are not warranted without more detailed studies

First Page Preview

First page PDF preview
You do not currently have access to this article.