 It last erupted about 7,000 years ago, producing two small lava flows that traveled to the west, along with a blanket of volcanic ash that extends several km to the north and east of the cone.The volcanic belt also contains three large shield volcanoes that were formed between 8 and 1 million years ago, called the Ilgachuz Range, Rainbow Range and the Itcha Range.The Chilcotin Group in southern British Columbia is a north-south range of volcanoes, thought to have formed as a result of back-arc extension behind the Cascadia subduction zone.