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Cobb Segment   »  Summary

Cobb Segment

A photograph is not available for this volcano.

Subregion Name:Northeastern Pacific Ocean
Subregion Detail:Juan de Fuca Ridge
Volcano Number:1301-011
Volcano Type: Submarine volcano
Volcano Status:Uranium-series
Last Known Eruption: 1180 BC (?) 
Summit Elevation: -2100? m - 6,890 feet
Latitude: 46.88°N 46°53'0"N
Longitude: 129.33°W 129°20'0"W

The Cobb Segment in the northern part of the Juan de Fuca Ridge, lies south of the Endeavour Ridge segment. Also known as the Northern Symmetrical or NSymm Segment, the 150-km-long Cobb Segment is the longest of the Juan de Fuca Ridge. It has a narrow, 1-2 km wide axial crest with a shallow graben that has a high point at a depth of about 2300 m. A prominent seamount with hydrothermal deposits at its summit lies just west of the axis high and was the source of a broad area of young, mostly sediment-free lava flows. As with other Juan de Fuca Ridge segments, a shallow magma chamber is thought to underlie the Cobb Segment, and a preliminary uranium-series date of Holocene age was obtained on a basaltic lava flow from the Cobb Segment.

Global Volcanism ProgramDepartment of Mineral SciencesNational Museum of Natural HistorySmithsonian Institution

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