From the USGS, an overview of this region's geology.

Operates seismograph stations, locates earthquakes in Washington, and disseminates information on regional earthquake and geologic hazard activity.

Part of the Department of Natural Resources. Includes bibliography of Washington geology, news, FAQ, links, and educational resources.

List of locations that are sources of obsidian across the state. Also includes a scientific bibliography.

Trips and photos, classifieds, site map, weather forecast, government contacts, and further reading.