Mount Silverthrone is an eroded lava dome on the northeast edge of a large caldera complex called the Silverthrone Caldera. It lies within the Coast Plutonic Complex, which is the single largest contiguous granite outcropping in the world. The plutonic and metamorphic rocks extend approximately 1,800 kilometers on the coast of British Columbia, southwestern Yukon and southeastern Alaska. In addition, Garibaldi, Meager, Cayley and Silverthrone areas are of recent volcanic origin. The volcanic terrain in the Silverthrone area is very similar to the Mount Meager massif further south. However, there is much more ice.