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COLORADO

George A. Jackson's Lost Mine

GEOLOGY OF THE AREA

The great mountain chain that comprises the Sierra Madre, Park, Gore, and Tenmile ranges consists of an uplifted core of ancient Precambrian igneous and metamorphic basement rock bounded by major fault zones on its eastern and western margins and intruded by several small Tertiary volcanic bodies. This block-faulted chain of ancient crystalline rock intersects the Colorado Mineral Belt near Climax. Here, three mountain ranges converge: the Gore Range which marches away to the northwest, the Tenmile Range which rises up to the north, and the Mosquito Range which wends its way to the south.

The main portal through the heart of the Gore and Park Ranges is Rabbit Ears Pass, located just southeast of Steamboat Springs. As one ascends the eastern flanks of the Park Range to Rabbit Ears Pass, they pass successively through older and older rock. Beginning with the upper Cretaceous shales and limestones at Muddy Pass, the traveler first passes through the distinctive lower Cretaceous clastic formation known as the Dakota Sandstone. This important marker bed is exposed all the way to the crest of the Park Range. Continuing westward, the traveler next encounters a thin band of older Paleozoic sedimentary rock followed by a vast terrane of ancient Precambrian igneous and metamorphic basement rock. These primordial gneisses, schists, migmatites, and granites are among the oldest rocks exposed at the surface in Colorado and comprise the uplifted core of the Sierra Madre and Park Ranges, most of the Gore Range, and the Tenmile Range to the south.

The jagged peaks that comprise the famous landmark known as Rabbit Ears Peak are the erosional remnants of a large volcanic plug composed of agglomeritic quartz latite.

It is one of several shallow Tertiary intrusive bodies that occur in the heart of the Park Range. Others crop out on Walton Peak and along the headwaters of Walton Creek.


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The mineral deposits of Routt County are indeed sparse and meager compared to the great mining districts located within the Colorado Mineral Belt. In Routt County, all of the gold-producing areas occur in the northeastern part of the county, near Hahns Peak. The small outlying districts of Slavonia, Farwell Mountain, Greenville, and Slater produced only minor amounts of the yellow metal. In the Hahns Peak area, the majority of the gold was recovered from the streams surrounding the peak. The best placers occurred in Deep Creek, Ways Gulch, Willow Creek, and at Little Red Park.

Disseminated lode deposits of gold-bearing pyrite occur on Hahns Peak near the Royal Flush Mine. Dispersed throughout the Tertiary quartz latite, these unique deposits were locally quite rich. In some ways they remind us of the great disseminated gold deposits at Carlin, Nevada except that the Hahns Peak deposits are miniscule in comparison. The small, subsidiary districts at Farwell Mountain, Greenville, and Slavonia were all founded on gold-bearing polymetallic sulfide veins. These ore deposits are hosted within the ancient Precambrian gneisses, schists, and migmatites that form the country rock in this area.

PROSPECTING POTENTIAL

The Park Range and adjoining Gore Range present a number of difficulties to the modern-day prospector, just as they did for the early gold-seekers over a hundred years ago. The area includes some of the most rugged country in Colorado and much of it is heavily forested. In addition, the area of interest near Walton Peak is poorly mineralized with little or no gold production from the streams that drain the mountain. Indeed, the main focus of mineralization in Routt County is at Hahns Peak, more than 30 miles to the northwest.

George Jackson always claimed that Rabbit Ears Peak was no more than 5 or 6 miles from the mine, but distances can be deceiving in the mountains. Prospectors should probably concentrate on Walton Peak and the adjoining Walton Creek drainage basin in their search for the lost mine. Harrison Creek, which drains the southern slopes of Walton Peak, should also be investigated. Finally, the crest of the Gore Range between Silver Creek (a tributary of the Yampa River) and Red Dirt Creek (a tributary of Muddy Creek) should also be


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surveyed while one is in the area. Small deposits of placer gold have been found along the headwaters of Red Dirt Creek and the area lies only 11 miles southeast of Walton Peak.

The Tertiary volcanics on Walton Peak and along the southern headwaters of Walton Creek certainly deserve a quick going-over, especially along the margins of the igneous bodies. The Precambrian country rock should not be overlooked in the search for gold-bearing veins. The deposits at Slavonia, Farwell Mountain, and Greenville are all hosted in Precambrian metamorphic rock.

A metal-detector would certainly be useful in the search for gold-bearing float, not to mention the gold cache left behind by the Jackson party back in 1868.