Several features in the Mount Cayley volcanic field were illustrated by Jack Souther in 1980, including Mount Cayley, Ember Ridge, Mount Fee, Cauldron Dome, Pali Dome, Slag Hill and Ring Mountain, the later of which he called Crucible Dome. This resulted in the recreation of a geologic map that showed the regional terrain and locations of the volcanoes. Souther conducted the first detailed study of Mount Cayley itself during this period. At least three stages of volcanic activity were identified at the volcano. He also hypothesized that the Ember Ridge domes shared a common magma source. However, significant variations in the percentage of phenocrysts in the six domes prove otherwise.