Sentinel Mountain is an 8,245-foot peak in the Belly River area of Glacier National Park in northern Montana’s Lewis Range, near the Canada–United States border. Rising sharply above the North Fork Belly River, it has nearly 2,900 feet of relief in one mile, and its runoff feeds Belly River tributaries. Officially named in 1929, the mountain reflects the park’s deep geologic history: sedimentary rocks deposited from the Precambrian through the Jurassic and shaped by the Lewis Overthrust, which began about 170 million years ago as older rock was thrust over younger Cretaceous rock. Its high elevation gives it a harsh alpine subarctic climate with snowy winters and frequent summer storms.