Sourdough Ridge Trail, Mt. Rainier National Park, Washington State. Two overnight backpackers pass by, heading east on the Sourdough Ridge Trail. The Emmons Glacier is the predominant view of the northeast side of Mt. Rainier from this section of the trail, which features a significant dry stone wall. Little Tahoma is visible on the skyline to the left of the summit of Mt. Rainier, a composite volcano, which is the highest mountain in Washington and the Cascade Range with a summit elevation of 14,411 feet.