The geography of northwestern British Columbia and Yukon, Canada is dominated by volcanoes of the Northern Cordilleran Volcanic Province formed due to continental rifting of the North American Plate. It is the most active volcanic region in Canada. Some of the volcanoes are notable for their eruptions, for instance, Tseax Cone for its catastrophic eruption estimated to have occurred in the 18th century which was responsible for the death of at least 2,000 Nisga'a people from poisonous volcanic gases, the Mount Edziza volcanic complex for at least 20 eruptions throughout the past 10,000 years, and The Volcano (also known as Lava Fork volcano) for the most recent eruption in Canada during 1904. The majority of volcanoes in the Northern Cordilleran Volcanic Province lie in Canada while a very small portion of the volcanic province lies in the U.S.