Describes the bedrock stratigraphy and structural aspects of the study area and the controversies on the structural geology and provides new evidence and interpretations. This CD also includes photographs, structural diagrams, and map of the study area at 1:48,000 scale.

Previous studies have shown the Escalante Valley, Utah, is subsiding due to groundwater withdrawal. The magnitude and spatial pattern of this cm/yr.-scale subsidence is mapped with satellite data from a synthetic aperture radar (SAR) using interferometric SAR (InSAR) processing techniques.

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.

Multiple episodes of diapirism, probably salt-generated, have determined the structural pattern of central Utah. The causative salt and other evaporites are integral components of the Arapien Shale of Middle Jurassic age, one of the most unusual stratigraphic units in central Utah.