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.

Box Elder County displays a variety of lithologic types in each of the major rock divisions: sedimentary, igneous, and metamorphic, in a typical Basin and Range setting. True to the basic structure most of its mountain ranges generally trend north-south, but the Raft River Range trends east-west. Each mountain range exhibits a variety of structural situations: most stratigraphic units are folded and faulted, and many are intruded by igneous rocks. 251 pages + 3 plates

Geologic exposures in the Salt Lake City region record a long history of sedimentation and tectonic activity extending back to the Precambrian Era. Today, the city lies above a deep, sediment-filled basin flanked by two uplifted range blocks, the Wasatch Range and the Oquirrh Mountains. The Wasatch Range is the easternmost expression of major Basin and Range extension in north-central Utah and is bounded on the west by the Wasatch fault zone (WFZ), a major zone of active normal faulting. During the late Pleistocene Epoch, the Salt Lake City region was dominated by a succession of inter-basin lakes. Lake Bonneville was the last and probably the largest of these lakes. By 11,000 yr BP, Lake Bonneville had receded to approximately the size of the present Great Salt Lake.