Columbia River Basalt Group
comparison with Panthalassa
- Puget_lobe_of_the_Cordilleran_ice_sheet.jpg (wikimedia.org)
- In the nearby Pacific Ocean, roughly 170 miles (270 km) west of Vashon Island, lies the 700-mile (1,130 km) tectonic boundary known as the Cascadia Subduction Zone, and as such, Vashon Island is one of many areas at risk for earthquakes or related natural disasters.
- Millions of years ago, vents and fissures opened under the Pacific Ocean and lava flowed forth, creating huge underwater volcanic mountains and ranges called seamounts. The Farallon tectonic plate that formed a part of the Pacific Ocean floor (separate from the Pacific plate) inched eastward toward North America about 35 million years ago and most of the sea floor subducted beneath the continental land mass of the North America plate. Some of the sea floor, however, was scraped off and jammed against the mainland, creating the dome that was the forerunner of today’s Olympics.
- down the Pacific coast
- up the Pacific coast
- Willapa River
- Deception Pass
- Pacific Ocean (Wikipedia)
The Pacific Ocean is the largest and deepest of Earth’s five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continents of Asia and Oceania in the west and the Americas in the east.
