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.

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.