Cobb Seamount
| Cobb Seamount | |
|---|---|
| Summit depth | 34 m (112 ft) |
| Height | 2,743 m (8,999 ft) |
| Summit area | 824 km2 (318 sq mi) |
| Location | |
| Coordinates | 46°44′N 130°47′W / 46.733°N 130.783°WCoordinates: 46°44′N 130°47′W / 46.733°N 130.783°W |
| Geology | |
| Type | Seamount (underwater volcano), guyot |
| Volcanic arc/chain | Cobb-Eickelberg Seamount chain |
| Age of rock | about 3.3 million |
| History | |
| Discovered by | MV John N. Cobb, 1950 |
Cobb Seamount is a seamount (underwater volcano) and guyot located 500 km (310 mi) west of Gray's Harbor, Washington, United States. Cobb Seamount is one of the seamounts in the Cobb-Eickelberg Seamount chain, a chain of underwater volcanoes created by the Cobb hotspot that terminates near the coast of Alaska. It lies just west of the Cascadia subduction zone, and was discovered in 1950 by MV John N. Cobb. By 1967, over 927 km (576 mi) of soundings and dozens of samples from the seamount had been collected.
Cobb Seamount is geologically interesting for its terraced, pinnacle structure, and its biological community. Like many other seamounts, Cobb Seamount acts as a biological center of diversity, and supports a dense oceanic ecosystem. Relatively convenient access and an interesting biological setting have made the seamount an object of several scientific cruises and dives.
Cobb Seamount lies 270 mi (430 km) off the coast of Washington, in the 8,500 ft (2,600 m)-deep Cascadia Basin.argon-argon dating of basalts retrieved from the volcano show that it is about 3.3 million years in age. Cobb Seamount's slopes average 12° in grade, and are indented by four prominent terraces at various depths; this morphology is partly the result of sub-aerial exposure and wave erosion at sea level and partly due to volcanic processes far below wave base. The volcano's pinnacle is generally flat, and is defined by a pocketed area approximately 880 m (2,887 ft) by 577 m (1,893 ft) in size.
Although it is one of over 100 underwater features in the region, Cobb Seamount is the only one known to extend well upwards into the region of the ocean penetrated by light. Like many other seamounts, Cobb Seamount is a local biological hotspot and functions as an "island of stability" for local organisms. It supports an extensive fish population, mostly Sebastes species and especially Sebastes miniatus. Bird life has been noted in the area of its summit, indicating that it is a prime fishing ground. For the complete known species inventory of Cobb Seamount, see Du Preez et al., 2015.
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