Matahpi Peak is a 9,370-foot mountain in Glacier National Park’s Lewis Range, rising above Sexton Glacier near Going-to-the-Sun Mountain. Like many peaks in Glacier, it is made of sedimentary rock laid down in ancient shallow seas from the Precambrian through the Jurassic. Its broader geologic setting took shape beginning about 170 million years ago, when movement along the Lewis Overthrust fault drove a huge slab of much older rock over younger Cretaceous rock. Matahpi Peak stands within this striking overthrust landscape, where rugged summits and glaciers expose an unusually clear cross-section of deep geologic time.