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CALIFORNIA

Lost Gunsight Mine

GEOLOGY OF THE AREA

The Death Valley depression harbors the lowest point in the United States (about 260 feet below sea level) and extends roughly 120 miles in a northwest-southeast direction. The valley and surrounding mountains and deserts constitute some of the most forbidding country in North America. At its northern end, the valley is bounded by the Last Chance Range (on the west) and the Grapevine Mountains (on the east). Both ranges are composed mostly of Paleozoic marine sediments. As one travels southward, the Cottonwood Mountains and Panamint Range rise up on the western side of the valley, while the Funeral Mountains and Amargosa Range loom up on the eastern side. The Cottonwood Mountains, like the Last Chance Range and Grapevine Mountains, are mostly composed of Paleozoic marine sediments, but in the southernmost part of the range a large Mesozoic granitic intrusion is exposed. This Mesozoic granite is one of several similar plutons that intrude the ancient Precambrian to Cambrian metamorphic and sedimentary basement rocks of the Panamint Range.

The Funeral Mountains are an uplifted block of ancient Precambrian to early Devonian metamorphic and sedimentary rocks. These rocks represent a virtually unbroken sequence of deposition extending some 220 million years.

The Amargosa Range marches southward from Boundary Canyon (the southern terminus of the Grapevine Mountains) to Copper Canyon (located about 7 miles south of Badwater). To the north, the Amargosa Range and the Funeral Mountains are very closely associated; indeed, there is really no intervening valley between them until one goes south of Echo Canyon and Death Valley National Monument. In this area, the Amargosa Range and the Black Mountains are similarly very closely associated. Further south, past Copper Canyon, only the Black Mountains form the eastern wall of

Death Valley. The Black Mountains are an uplifted, northwest-southeast trending block of ancient basement rock wedged between the Death Valley and Furnace Creek fault zones. They are made up of Precambrian to Cambrian metamorphic and sedimentary country rock which is intruded and overlain by younger Mesozoic granite plutons and younger still Tertiary volcanic rocks. Tertiary volcanics include basalts, rhyolites, and pyroclastics; one deposit of pyroclastic rocks consists of brecciated tuffs 500 feet thick! These pyroclastic rocks bear witness to the violent history of this part of the Black Mountains during early-Tertiary time.

As one travels southward, the valley constricts somewhat as the Owlshead Mountains crowd in on the southern end of the Black Mountains. The Owlshead Mountains form the western wall of Death Valley in this area and are mostly composed of Mesozoic-age granites. The southern spur of the Black Mountains is made up of Precambrian to Cambrian metamorphic and sedimentary rocks.

Further south, the southern terminus of Death Valley is finally encountered. The valley is bounded to the south by the heavily faulted Avawatz Mountains. These mountains consist of an uplifted core of ancient Precambrian metamorphic basement rock intruded by small Mesozoic granitic stocks. The Ibex Hills and Saddle Peak Hills pop up along the southern end of Death Valley. Both consist of Precambrian to Cambrian metamorphic and sedimentary rocks.

Many small hills and buttes in the Death Valley basin (and also in the surrounding deserts) are composed of Tertiary volcanic rocks. Examples include Shoreline Butte (located near Ashford Junction) and the Dublin Hills (located near Shoshone).

PROSPECTING POTENTIAL

The area of interest for the Lost Gunsight Mine presents some daunting problems for the prospector in that it is extremely barren and remote and encompasses a vast area. On the other hand, it's a prospector's delight in that it has virtually no vegetative cover and the remoteness of the area precludes thorough and detailed prospecting by anyone. Small deposits may still lie hidden in the area.

Prospectors may want to concentrate on the country paralleling the route of the 49'ers through Death Valley. For example, the Manly-Bennett party journeyed southward from Furnace Creek Wash to Bennett's Well, and then southwestward along the eastern edge of the Panamints to the Six Springs Canyon area. They headed west across the Panamints here. Prospectors may want to focus on the eastern foothills of the Panamints, especially the area just east of Panamint City. This includes

Johnson Canyon, which drains the eastern slope of the Panamints and heads less than 2 miles from the Panamint City silver district.

The Jayhawker party traveled northward from Furnace Creek Wash to the area near Stovepipe Wells. Here they turned west, passing around Tucki Mountain and into Emigrant Wash, which they used to climb out of Death Valley. Again, the eastern flank of the Panamints seems to offer the best potential for prospectors. The Panamints are the most heavily mineralized of all the Death Valley ranges. Consequently, they have been heavily prospected, but nevertheless still offer some potential for future strikes.

Many small hills, buttes, and mounds in the Death Valley basin (and also in the surrounding deserts) are composed of Tertiary volcanic rocks. The lost hill of silver may be hosted in one of these.