Castle Rock is part of the Pacific Ring of Fire that includes over 160 active volcanoes and is in the Klastline Group of the Northern Cordilleran Volcanic Province and last erupted in the Pleistocene.
Castle Rock is included in the Pacific Ring of Fire, a region with more than 160 active volcanoes. It is part of the Klastline Group in the Northern Cordilleran Volcanic Province and its most recent volcanic activity happened during the Pleistocene period.