The southeastern portion of the range is bounded by the White Knob Mountains, Pioneer Mountains, Bould Mountains, and the basins of Marsh Creek, Valley Creek and Warm Spring Creek. The southwestern boundaries are formed by forks of the Payette River, also a Snake River tributary.[2] The height of the mountains gradually increases from west to east, sloping up towards the Continental Divide. The highest peak is West White Mountain in the eastern subrange, rising to 10,442 feet (3,183 m).