The Cayley volcanic field is a deeply dissected basaltic andesite to rhyodacitic complex that covers a broad area between the Cheakamus and Squamish river valleys in the central Garibaldi volcanic belt. Mount Cayley itself was formed during at least three periods of activity primarily during the Pliocene and Pleistocene, but activity at satellitic dominantly subglacial vents along a N-S line both north and south of Mount Cayley continued in the late Pleistocene and Holocene. Vents in the Cheakamus Valley formed a 22-km-long lava flow sequence prior to 50,000 years before present that was topped by esker-like flows of late Pleistocene age. The youngest lava flows from Pali Dome West and from the subglacial Slag Hill volcano north of Mount Cayley were not impounded by ice at low elevations, implying that they erupted after the end of the Fraser Glaciation (less than 10,000 years ago). Large volcanic landslides have occurred at heavily eroded Mount Cayley during the Holocene. At least five hot springs are present in valleys adjacent to the volcano, and shallow earthquakes have occurred in the vicinity.