Cobb Seamount

The Cobb Segment is in the northern part of the Juan de Fuca Ridge, south of the Endeavour Ridge segment. This 150-km-long segment, also known as the Northern Symmetrical or NSymm Segment, is the longest of the Juan de Fuca Ridge. It has a narrow axial crest, 1-2 km wide, with a shallow graben that has a high point at about 2,300 m depth. 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 source is thought to underlie the Cobb Segment, and a preliminary Uranium-series date of Holocene age was obtained on a basaltic lava flow.