Ilgachuz, and Itcha ranges. These fairly dissected shield volcanoes lie on the northern end of the Chilcotin Group lava plateau and distal lava flows at the margins of the shield volcanoes merge imperceptibly with flat-lying lava flows comprising the Chilcotin Group lava plateau. Unlike the Chilcotin Group basalt, which is not associated with any felsic derivatives, the volcanoes of the central Anahim Volcanic Belt are markedly bimodal, comprising a mixed assemblage of basalt and peralkaline silicic rocks. While volcanoes of the Anahim Volcanic Belt appear to merge laterally with the Chilcotin Group lavas, the particular nature and connection between the Anahim Volcanic Belt and the Chilcotin Group is unknown. However, volcanoes within the Anahim Volcanic Belt usually become younger from coastal British Columbia to near the small city of Quesnel further east, indicating these volcanoes may have formed as a result of the North American Plate passing over a possible mantle plume known as the Anahim hotspot, whereas the Chilcotin Group is related to back-arc basin volcanism. Nazko Cone, a cluster of basaltic cinder cones in the Nazko area west of Quesnel forms the youngest and most easterly part of the Anahim Volcanic Belt with dates of 7,200 years. The Explorer Ridge, an underwater mountain range lying west of Vancouver Island on the Coast of British Columbia, consists of a north-south trending rift zone. It contains one major segment known as the Southern Explorer Ridge, along with other smaller segments, such as the Northern Explorer Ridge. With a depth of , the Southern Explorer Ridge is relatively shallow in comparison with most other rift zones of the northeast Pacific Ocean, indicating there has been considerable volcanic activity along this part of the Explorer Ridge in the past 100,000 years. Magic Mountain, a large hydrothermal vent area on the Southern Explorer Ridge, is a scene of this volcanic activity. Unlike most hydrothermal systems found in the Pacific Ocean, the Magic Mountain site is situated outside the primary rift zone. The source for the hydrothermal fluid that fuels Magic Mountain probably rises along fracture systems associated with a recent episode of rifting that, in turn, followed a massive outpouring of lava. In contrast, the Northern Explorer Ridge has evolved into a complex compound structure consisting of several rift basins bounded by half-graben and arcuate shaped faults with a superimposed pattern of rhombohedral grabens and horsts. The Endeavor Segment, an active rift zone