The massif resides in the middle of a north-south trending zone of volcanism called the Mount Cayley volcanic field. It consists predominantly of volcanoes that formed subglacially during the Late Pleistocene age, such as Pali Dome, Slag Hill, Ring Mountain and Ember Ridge, but activity continued at Pali Dome and Slag Hill into the Holocene epoch. The Mount Cayley volcanic field is part of the Garibaldi Volcanic Belt, which in turn represents a northern extension of the Cascade Volcanic Arc. Volcanism of the Cascade Arc is largely a result of the Juan de Fuca Plate sliding under the North American Plate at the Cascadia subduction zone.