Thunderbird Mountain is an 8,805-foot peak in Glacier National Park’s Livingston Range in Montana, standing on the Continental Divide with Thunderbird Glacier just northeast of it. Like many mountains in the park, it is made of sedimentary rock deposited in ancient shallow seas from the Precambrian through the Jurassic. Its present shape reflects the broader geologic forces that formed Glacier’s landscape: beginning about 170 million years ago, movement along the Lewis Overthrust fault pushed a huge slab of much older Precambrian rock over younger Cretaceous rock, helping create the park’s striking mountain scenery.