Split Mountain, an 8,797-foot peak in Glacier National Park’s Lewis Range, rises from a rugged chain of mountains shaped by distinctive northern Rocky Mountain geology. Like many peaks in the park, it consists of sedimentary rock laid down in ancient shallow seas from the Precambrian through the Jurassic. Its deeper geologic significance is tied to the Lewis Overthrust, which began about 170 million years ago and pushed a vast slab of older Precambrian rock over younger Cretaceous rock. Set in an alpine subarctic climate with long snowy winters and short summers, the mountain is part of a landscape prized for both dramatic scenery and visible evidence of Montana’s formation.