Level IV: (1d) Coast Range Volcanics
The Volcanics ecoregion consists of steeply sloping mountains and capes underlain by fractured basaltic rocks. Elevation generally varies from 600 to 4100 feet (180 to 1250 m), although in some places the volcanic rock extends down to sea level. The region is marked by columnar and pillow basalt outcrops. Its mountains may have been offshore seamounts engulfed by continental sediments about 200 million years ago. High gradient, cascading streams and rivers occur, and the basaltic substrate preserves summer flows that are more consistent than streams on the sedimentary rocks in surrounding ecoregions.
The streams still support runs of spring chinook salmon and summer steelhead. The region’s Douglas-fir plantations are heavily logged. Mature forests consist of Douglas-fir, western hemlock, salal, sword fern, vine maple, Oregon grape, and rhododendron. Wetter slopes and riparian areas may support western redcedar, bigleaf maple, red alder, salmonberry, and oxalis. Grassy coastal headlands and mountaintop balds feature Roemer’s fescue, thin bentgrass, California oatgrass, and diverse forbs.
This large but disjunct ecoregion covers 2,043 square miles (5,291 km2) in Oregon and 1,542 square miles (3,994 km2) in Washington, including parts of the Olympic and Siuslaw National Forests and the Cummins Creek and Rock Creek Wildernesses, as well as higher elevations in the Cape Meares National Wildlife Refuge. California has not been mapped yet.
Origianal Work: EPA