The Hells Gate Roadless Area comprises about 31, 200 acres in the northern part of the Tonto National Forest. It lies beneath the Mogollon Rim between the communities of Payson and Young. The area is roughly a 4 by 15 mi strip along the deeply incised segment of Tonto Creek and along a 2 mi segment of Haigler Creek at its intersection with Tonto Creek. Elevations range from 2,960 ft in the lower Tonto Creek gorge near Gisela, in the southeastern part of the area, to 6,200 ft in the Green Valley Hills, in the northern part of the area. Local relief in the deep canyon of Tonto Creek is commonly greater than 1,000 ft. Hells Gate is the geographic name for the canyon at the confluence of Tonto Creek and Haigler Creek. Foot trails cross Tonto Creek at Hells Gate and between Houston Pocket and McDonald Pocket. Descent into Tonto Creek elsewhere is extremely difficult.
The Hells Gate area lies in the central part of the Tonto Basin, which consists of Tonto Creek and tributaries draining the Mogollon escarpment and the northern Sierra Ancha. These streams dissect a table land which is the unconformable surface at the base of the Paleozoic section and the Mogollon Rim. This tableland is a part of the Colorado Plateau margin, which has been slightly structurally disrupted by late Cenozoic faulting and from which most of the Middle Proterozoic and
Paleozoic strata have been stripped by subsequent erosion. Early Proterozoic rocks constitute about ninety percent of the exposed rocks in the roadless area and are composed of granite, granophyre, and intrusive and extrusive rhyolite (Conway, 1983).
Aeromagnetic map of the Hells Gate Roadless Area, Gila County, Arizona