Tuya Butte formed when magma intruded into and melted a vertical pipe in the overlying Cordilleran Ice Sheet. The partially molten mass cooled as a large block, forming the highly developed hyaloclastite and pillow lava with gravity flattening its upper surface. Horizontal columns occur at numerous locations along the periphery of the mass. The absence of glacial erosion of the tuya suggests that it erupted during the Pleistocene. The volcano has no summit crater or obvious vent, suggesting the volcano was fed by a fissure, although several indictions suggest a vent location near a large cirque on the north face. Other subglacial volcanoes can be found in the Wells Gray-Clearwater volcanic field and the Garibaldi Volcanic Belt.