South Park, the famous "Bayou Salado" of the mountain men, is one of three "holes" or "parks" that grace the Rocky Mountains of Colorado. The northwestern edge of South Park is bounded by the Mosquito Mountains which form the Continental Divide in this part of the Rockies. The Mosquito Mountains are an uplifted wedge of ancient Paleozoic sediments overlain in some places by younger Cretaceous sediments and intruded by numerous Laramide stocks and plugs. In the northeastern portion of the range, near Kenosha Pass, ancient Precambrian basement rock crops out at the surface. These Precambrian crystalline rocks consist of truly ancient schists and gneisses and slightly younger granites.
The area in the immediate vicinity of Deadman Gulch consists mostly of ancient Precambrian metamorphics and granites bounded on the west by a large northwest-southeast trending fault. The fault serves as the boundary between the Precambrian crystalline rocks described above and much younger Cretaceous sedimentary rocks to the west. These Cretaceous sediments consist of sandstones and shales which form the crest of the Mosquito Mountains in some parts of the range. Just west of the fault and parallel to it, a large Laramide intrusion crops out above the old site of Tarryall. But this is not the only Laramide intrusion in this part of the state. The Mosquito Mountains and surrounding country are peppered with small Laramide plugs, stocks, and plutons.
The headwaters of Deadman Gulch originate high above South Park within the ancient Precambrian basement rock described above. The gulch cuts through a small Laramide plug as it descends from the mountains into South Park. In its lower reaches it cuts through Cretaceous and Tertiary sedimentary rocks.
The nearest mining district to Deadman Gulch is the Tarryall Creek District, located only 8 miles to the southwest. The Tarryall Creek District is famous for the tremendous placer deposits found on Tarryall Creek, Deadwood Creek, and Little French Creek. But the district also contained lode deposits. Located near the headwaters of Middle Tarryall Creek, the lode deposits consisted of both veins and replacement bodies. The veins contained gold-bearing pyrite while the replacement bodies consisted of native gold, pyrite, and magnetite.
Placer gold was also found in small quantities in Jefferson Creek, Michigan Creek, and Ohler Gulch. These creeks lie just southwest of Deadman Gulch.
Prospectors face a bit of a challenge in their search for the Lost Mine of Dead Man's Gulch. First and foremost, they are entering a country that has been heavily prospected since 1859. It is quite unlikely that any large deposits of gold still remain in the area. Still, the area is richly mineralized with virtually every stream containing some placer gold. It is quite possible that a small but rich pocket of gold ore still lies hidden somewhere in the Deadman Gulch area. Indeed, the nearby Tarryall District is home to a number of skarn deposits containing native gold, pyrite, and magnetite. Similar contact metamorphic deposits may exist near Deadman Gulch.
Prospectors may want to begin their search for the lost mine along the headwaters of Deadman Gulch. A good place to start would be the small Laramide plug that crops out near the foot of the range, just north of Jefferson. Deadman Gulch cuts through the western edge of this intrusion as it descends the mountains to South Park. The surrounding country rocks may harbor a hidden skarn deposit of gold-bearing ore.
Prospectors may also want to work their way upstream into the Precambrian schists and gneisses at the head of the gulch. This is a vast and rugged area which may yet conceal a rich pocket of gold. The high mountain peaks extending from Georgia Pass northeastward to Whale Peak should be considered as well as the rugged country leading up to them. This area encompasses the headwaters of Jefferson Creek, Deadman Gulch, Guernsey Creek, and Beaver Creek. It is almost entirely overlain by ancient Precambrian metamorphic country rock.