in North America. Geology Background A number of mechanisms have been proposed to interpret the origin of volcanism in the Anahim Volcanic Belt. This includes rift propagation and melting of mantle associated with lithospheric fracturing due to flexuring of the crust along the northern edge of the subducting Juan de Fuca Plate. However, insignificant evidence exists to support these hypotheses. The most common and best mechanism used to explain Anahim Belt volcanic activity is a stationary hotspot. This is supported by a well-defined progression in age of volcanism from west to east along the belt that compares well with the age trend of the Yellowstone hotspot track. The North American Plate moves westward over the hotspot at a rate of between per year. Nazko Cone, a volcanic cone east of the Itcha Range, is centred near the Anahim hotspot. The Anahim hotspot is underlain by a low-velocity anomaly that extends approximately into the mantle north of the Juan de Fuca slab. However, this low-velocity anomaly may extend deeper southward beneath the Juan de Fuca slab. Coupled with the well documented temporal progression of surface volcanism, this has led to the conclusion that the Anahim hotspot is supplied by a mantle plume over slab edge flow. A small high-velocity anomaly east of Nazko Cone marks the eastern extent of the Anahim hotspot track. Magmatism in the Anahim Volcanic Belt can be traced as far back as 10–14 million years ago with the emplacement of dike swarms and plutons as well as the eruption of rhyolite flows and breccias on the British Columbia Coast. The slow continuous westward motion of the North American Plate during the late Neogene positioned the Anahim hotspot further east at the Chilcotin Plateau where volcanic activity built the Rainbow Range shield volcano 8.7 to 6.7 million years ago. Volcanism then shifted eastwards, in displacement contrary with the North American Plate's movement, 6.1 million years ago to construct the Ilgachuz Range shield volcano. Renewed volcanic activity southeast of the Ilgachuz Range starting 3.5 million years ago led to the creation of the Itcha Range, the youngest of the three Anahim shield volcanoes. The Itcha Range continued to be an area of Anahim hotspot volcanism well into the Quaternary period (2.58 million years ago to present). Structure The Itcha Range is the smallest shield volcano in the Anahim Volcanic Belt in terms of area covered. Unlike the Rainbow and