Big Raven Formation
The Big Raven Formation is a stratigraphic unit of Holocene age in northwestern British Columbia, Canada. Description The Big Raven Formation is part of the Mount Edziza volcanic complex. This is the second largest eruptive centre in the Northern Cordilleran Volcanic Province, attaining a volume of and an area of . It consists of shield volcanoes, stratovolcanoes, cinder cones and lava domes that have formed in the last 12 million years. Lithology The Big Raven Formation consists primarily of alkali basalt and hawaiite. These rocks form lava flows and small volcanic cones throughout the Mount Edziza volcanic complex. A small volume of comenditic trachyte pumice is assigned to the Sheep Track Member, the only formally named sub-unit of the Big Raven Formation. Distribution The Big Raven Formation has a volume of , making it the least voluminous geological formation of the Mount Edziza volcanic complex. It includes the Desolation Lava Field on the northern slope of Mount Edziza, the Snowshoe Lava Field on the southwestern slope of Ice Peak, the Mess Lake Lava Field east of Mess Lake, Nahta Cone near the northern edge of the Arctic Lake Plateau, Kana Cone on the extreme northern flank of the Mount Edziza