The Big Cottonwood area lies in the highest portion of the Wasatch Mountains southeast of Salt Lake City. It contains exposed geologic features developed during two billion years of earth history. Discoveries of small but rich mineral deposits within the area led to a colorful, moderately productive, century-long period of metal mining. While there is no mining activity in the Big Cottonwood mining district today, the area is of considerable interest to students of regional geology and to numerous visitors to the mountain recreational areas. Major thrust faulting is well exposed in outcrops and in mine workings and is of economic importance on a regional scale. The unusual occurrence of the major ore bodies, at the intersections of steep fissure veins with several overthrust planes, similar to that of deposits mined in the adjoining Little Cottonwood (Alta) and American Fork districts to the south, is a classic regional feature. The small deposits in the older Precambrian rocks at the eastern edge of the district present features not seen elsewhere in the state. This report presents new detail on these and other aspects of the geology of the district, and records available geology and history of the many formerly-active underground mines. It presents an update on regional geology. It is written for readers of many interests, not merely for economic geologists. 98 pages + 4 plates

Whether you are a geologist, history buff, or rockhound, this booklet will be a helpful guide to Utah?s mining districts. The booklet is divided up into three parts: the first part provides general information on what a mining district is, how many mining districts are in Utah, types of mineral deposits found at these districts, and landownership issues. The second part includes individual mining-district discussions containing information on location, production, history, geology, mineralogy, and current/future operations. The third part includes a glossary of geologic terms and other useful resources in the appendices, such as a descriptive list of minerals found in the districts, geologic time scale, and a list of mineral resources of the mining districts.

This brochure is an introduction to Salt Lake County's geologic resources and the important role they play in our economy and everyday lives. Understanding the dynamic forces that form geologic resources and the factors that influence their development and use helps us realize the value of the earth's natural assets. The resources are divided into three categories: 1) metallic, 2) non-metallic, and 3) energy. Salt Lake County's resources are numerous, therefore only a few of particular significance to the county are discussed in detail. Their origin, mining history, extraction, and common uses are reviewed. The remaining resources and pertinent data are included in Tables 1, 2 and 3. A generalized geologic map, generalized geologic time scale, geologic resource map, and glossary are included for reading aids.

This bulletin serves not only to introduce the non-geologist to the rich geology of Millard County, but also to provide professional geologists with technical information on the stratigraphy, paleontology, and structural geology of the county. Millard County is unique among Utah’s counties in that it contains an exceptionally complete billion-year geologic record. This happened because until about 200 million years ago the area of present-day Millard County lay near sea level and was awash in shallow marine waters on a continental shelf upon which a stack of fossil-bearing strata more than 6 miles (10 km) thick slowly accumulated. This bulletin summarizes what is known about these strata, as well as younger rocks and surficial deposits in the county, and provides references to scientific papers that describe them in greater detail. Mountains North 30 x 60 (1:100,000-scale) quadrangles. These companion maps and this bulletin portray the geology of Millard County more completely and accurately than any previously published work.