Mount Brown, in Liberty County in northern Montana, is the highest point in the county and on East Butte, and the second-highest peak in the Sweet Grass Hills. Rising sharply above the plains, it stands out as a landmark visible for many miles. The mountain is an exposed laccolith formed about 50 million years ago when igneous material intruded into older sedimentary rock, leaving a resistant core after erosion. Its runoff flows north toward the Milk River, and its slopes support elk, mule deer, and white-tailed deer. The Sweet Grass Hills have long been culturally important, especially as sacred ground to the Blackfoot and other tribes.