British Columbia, also called the Stikine Volcanic Belt, is the most active volcanic region in Canada. It comprises a large number of small cinder cones and associated lava plains, and three large, compositionally diverse volcanoes, known as the Level Mountain, the Mount Edziza volcanic complex, and Hoodoo Mountain. In the south the volcanic province is somewhat narrow and crosses diagonally through the northwesterly structural trend of the Coast Mountains. Farther north it is less clearly defined, forming a large arch that swings westward through central Yukon. Volcanoes within the British Columbia portion of the Northern Cordilleran Volcanic Province are disposed along short, northerly trending en-echelon segments which, in the British Columbia portion of the volcanic province, are unmistakably involved with north-trending rift structures including synvolcanic grabens and half-grabens similar to the East African Rift, which extends from the Afar Triple Junction southward across eastern Africa. The Northern Cordilleran rift system formed as a result of the North American continent being stretched by extensional forces as the Pacific Plate slides northward along the Queen Charlotte Fault to the west, on its way to the Aleutian Trench, which extends along the southern coastline of Alaska and the adjacent waters of northeastern Siberia off the coast of Kamchatka Peninsula. As the continental crust stretches, the near-surface rocks fracture along steeply dipping cracks parallel to the rift known as faults. Hot basaltic magma rises along these fractures to create passive lava eruptions. The compositions of lavas in the Northern Cordilleran Volcanic Province are mantle-derived alkali olivine basalt, lesser hawaiite and basanite, which form the large shield volcanoes and small cinder cones throughout the volcanic province. Many of them contain inclusions of lherzolite. The large central volcanoes of the volcanic province consist largely of trachyte, pantellerite, and comendite lavas. These lava compositions were formed by fractionation of primary alkali basalt magma in crustal reservoirs. A region of continental rifting, such as the Northern Cordilleran Volcanic Province, would support the development of high-level reservoirs of sufficient size and thermal capacity to sustain prolonged fractionation. The Anahim Volcanic Belt extends from coastal British Columbia across the Coast Mountains into the Interior Plateau. Its western end is defined by alkaline intrusive and comagmatic volcanic rocks of the Bella Bella-King Island complex, exposed in fjords and islands of the western Coast Mountains. The central portion of the Anahim Volcanic Belt contains three complex shield volcanoes, known as the Rainbow,