The boundaries of the Hart Ranges are the Rocky Mountain Trench and the McGregor Plateau on the west/southwest, the Peace Reach of Williston Lake on the north, and a certain line of demarcation with the Rocky Mountain Foothills to the east/northeast. The southern boundary is at Jarvis Creek. Mount Ida and Mount Sir Alexander are South of Jarvis Creek and are in the Continental Ranges, which comprise the main and best-known part of the Rocky Mountains and run all the way south to Marias Pass in Montana.