Paralleling the Canadian Cascade Arc to the northeast is an area composed of minor basaltic lava flows. This zone, known as the Chilcotin Group, formed as a result of back-arc basin volcanism behind the Canadian Cascade Arc, in response to ongoing Cascadia subduction. Volcanic activity began 31 million years ago, but most of the volcanism occurred during two younger magmatic periods, the first between 6.0 and 10 million years ago and the other between 2.0 and 3.0 million years ago. This indicates that most Chilcotin Group volcanism corresponded with volcanism in the Pemberton Belt, although some of the younger Chilcotin lavas were erupted during early stages of Garibaldi Belt volcanism. A few volcanic eruptions have occurred in the Chilcotin Group in the last 1.6 million years.