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UTAH

The Lost House Range Placers

GEOLOGY OF THE AREA

The House Range stretches 60 miles from Sand Pass and the Fish Spring Mountains southward to the Wah-Wah Valley. The House Range trends north-south and is less than 10 miles wide throughout its entire length. The crest of the range is dominated by two peaks, Swasey Peak (elevation: 9678 feet) and Notch Peak (elevation: 9655 feet). Both are composed of ancient Cambrian sedimentary rocks.

The House Range is part of the extensive Basin and Range Province of North America. It is a classic example of an uplifted mountain block or horst bounded by two downthrown grabens (Tule Valley and Sevier Valley). The country rock or host rock in the House Range consists of gently folded

and plunging Cambrian and Ordovician sedimentary rocks intruded by a small Jurassic-age granitic pluton. The pluton forms the core of Sawtooth Mountain near the center of the range. In addition, a series of younger Tertiary-age tuffs and ash-flow tuffs occurs in the southern portion of the House Range. These exposures are quite limited in extent.

The Cambrian and Ordovician sediments consist of a thick sequence of limestones, shales, and quartzites, some of which are extremely fossiliferous. The Wheeler Shale and Marjum Formation in particular have been a rich source of trilobites for many years.

PROSPECTING POTENTIAL

The House Range of west-central Utah has been prospected off and on for over two centuries. Unfortunately, the House Range has never been a big producer of gold. Only 500 ounces are reported from the placer deposits in Miller Canyon and the Amasa Valley. Most of this gold was recovered during the 1930's, although some mining activity continues today. The gold here has always been difficult to recover. The area is remote and extremely dry while the gold itself occurs mostly as a fine dust.

Prospectors should probably concentrate on the canyons and ravines that drain the slopes of Sawtooth Mountain, near the center of the range.

This area includes the old placer mining sites in Miller Canyon and the Amasa Valley. Prospectors may also want to search for the source of the placer gold in the rocks above the canyon floors. The contact between the Jurassic pluton and the surrounding limestones and shales is intriguing, although mineralization associated with the intrusion seems to be minimal. Prospectors may want to concentrate on the fault zones in the area, especially those that cut through the local limestones. The source of the House Range placers has never been found. The original lode deposits were probably quite small and have more than likely weathered completely away. It is quite possible that other small deposits lie hidden somewhere in the vicinity of Sawtooth Mountain.