The St. Elias Mountains form the highest coastal mountain range on Earth. It formed due to the subduction of the Yakutat microplate underneath the North American Plate. The Yakutat microplate is a wedge shaped oceanic plateau with a thickness of . Similar to the adjacent Pacific plate, which has a crustal thickness of , the Yakutat plate is moving northwestward at a rate of per year with respect to North America. The Yakutat plate is transported northwards along the active Fairweather Fault, which probably started more than 35 million years ago. Due to its thickness, the Yakutat plate is buoyant, resulting in surface uplift of the overriding North American plate, which formed the Talkeetna Mountains and the Alaska Range in Southcentral Alaska, located above the subducted part of the Yakutat plate.