Puget Sound faults about 1100 years ago (AD 900—930) an earthquake of magnitude 7+ uplifted Restoration Point and Alki Point, dropped West Point (the three white triangles in the Seattle Basin on the map), caused rockslides in the Olympics, landslides into Lake Washington, and a tsunami on Puget Sound. It extends as far east as (and probably terminates at) the Rattlesnake Mountain Fault Zone (RMFZ; the southern extension of the SWIF) near Fall City. This seems geologically reasonable, as both the SWIF and RMFZ appear to be the contact between Tertiary Crescent Formation basement of Puget Sound on the west and the older
Puget Sound honor of Peter Puget, a Huguenot lieutenant accompanying him on the Vancouver Expedition. This name later came to be used for the waters north of Tacoma Narrows as well. A different term for Puget Sound, used by a number of Native Americans and environmental groups, is "Whulge" (or "Whulj"), an anglicization of the Lushootseed name "x̌ʷə́lč", which means "sea, salt water, ocean, or sound". The USGS defines Puget Sound as all the waters south of three entrances from the Strait of Juan de Fuca. The main entrance at Admiralty Inlet is defined as a line between Point Wilson on the