Region 3: The Northern Rocky Mountains

In the far northeast corner of Washington State is a small arm of the Rocky Mountain system. The Rocky Mountains formed about 70 million years ago when an oceanic plate began subducting under the North American plate. The angle of subduction was significantly shallower than usual, causing the Rockies to form much farther inland.

Metallic Resources

Metallic resources are limited in this region. In Ferry County, Washington, mining operations began in the Kettle River-Buckhorn Mountain area. The mine is an underground facility designed to maintain as small a footprint as possible in order to minimize environmental impact. In the year 2013, the mine had a gold equivalent production (wherein silver production is converted to a gold equivalent) of 42 million grams (150,000 ounces).

The other metallic mining operation lies in Pend Oreille County, Washington. This mine accesses a lead-zinc ore body that is located in a narrow belt of sedimentary, volcanic, and metamorphic rocks.

Non-metallic Resources

Non-metallic resources in this region include sand, gravel, and stone. These materials are used as building materials for roads and other infrastructure in the region and are also shipped outside the region. Commercial-size quarries are found in the area.