Nazko cone is a small, tree-covered volcano in central British Columbia, approximately 75 km west of Quesnel. It is believed to be the easternmost expression of the Anahim hot spot that stretches across central British Columbia from Nazko to the Pacific Ocean. The volcano comprises lava flows, a composite cinder cone, and air-fall tephra. The sequence of eruption at Nazko started with the eruption of two distinct series of fluid lava flows, an older, grey basalt overlain by a younger, darker black basalt. The passive lava eruptions were followed by a period of explosive, pyroclastic eruptions [MOV, 3.1 Mb, player] of volcanic bombs and ash. This explosive activity built three overlapping cinder cones that were breached by the eruption of two lava flows near the end stages of the explosive eruptions. Finally, explosive volcanic activity scattered tephra to the north and east of the cones. The tephra deposits are deepest near the cones (>3 m) and thin to less than a few centimetres only a few kilometres away, suggesting that the explosive eruptions were relatively small. However, scientists at the Geological Survey of Canada surmise that this last eruption at Nazko cone may have started forest fires because charcoal is found within the tephra layer.

The lowermost (hence oldest) lava flows at Nazko volcano have been dated at approximately 340 000 years using the K-Ar method. The youngest deposits of air-fall tephra were dated indirectly by analyzing burned wood within the tephra; the burned wood ranges from 10 000 to 7000 radiocarbon years old. The ages for the tephra can be confirmed geologically because the air-fall material is found on top of glacial till deposited during the Fraser Glaciation, which ended about 10 000 years ago. The cinder cones at Nazko are currently mined for their valuable resources of scoria, which is used for light-weight aggregate, landscaping and groundcover, and in agricultural and horticultural applications as a soil additive (Figure A14).

The most immediate hazard relating to future eruptions from Nazko cone is of local concern only and includes the possibility of forest fires and the disruption of local air traffic should an ash cloud be produced.

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• Cinder cone eruption (0:06-0:24 of Ashfall) [MOV, 8.9 Mb, player]
  (© 1995 IAVCEI)

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