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.

Lake Bonneville: A Scientific Update showcases new information and interpretations about this important lake in the North American Great Basin, presenting a relatively complete summary of the evolving scientific ideas about the Pleistocene lake. A comprehensive book on Lake Bonneville has not been published since the masterpiece of G.K. Gilbert in 1890. Because of Gilbert's work, Lake Bonneville has been the starting point for many studies of Quaternary paleolakes in many places throughout the world. Numerous journal articles, and a few books on specialized topics related to Lake Bonneville, have been published since the late 1800s, but here the editors compile the important data and perspectives of the early 21st century into a book that will be an essential reference for future generations. Scientific research on Lake Bonneville is vibrant today and will continue into the future. - Makes the widespread and detailed literature on this well-known Pleistocene body of water accessible - Gives expositions of the many famous and iconic landforms and deposits - Contains over 300 illustrations, most in full color - Contains chapters on many important topics, including stratigraphy, sedimentology, hydrology, geomorphology, geochronology, isostasy, geophysics, geochemistry, vegetation history, pollen, fishes, mammals, mountain glaciation, prehistoric humans, paleoclimate, remote sensing, and geoantiquities in the Bonneville basin

With the tremendous growth of population in this and neighboring states, there are more collectors than ever before and with the rapidly escalating prices for mineral and fossil specimens in the retail market, there is a great demand for displayable material. It has become necessary for professional geologists, hobby collectors, and commercial collectors to recognize each others existence and to try to work together within a framework of regulation, courtesy, and common sense so that material of scientific value is not lost and undue restrictions are not placed upon collecting. There is a continuing need for collectors and professionals to work together with resource managers and legislators to develop workable laws and rules affecting the collecting of minerals and fossils. This publication contains details information about collecting areas, divided by county to make for ease of use. Each collecting area contains information about the minerals, rocks, or fossils present, map recommendations, and other helpful tips on getting to the sites.

This report presents the results of the Utah Quaternary Fault Parameters Working Group (hereafter referred to as the Working Group) review and evaluation of Utah’s Quaternary fault paleoseismic-trenching data. The purpose of the review was to (1) critically evaluate the accuracy and completeness of the paleoseismictrenching data, particularly regarding earthquake timing and displacement, (2) where the data permit, assign consensus, preferred recurrence-interval (RI) and vertical slip-rate (VSR) estimates with appropriate confidence limits to the faults/fault sections under review, and (3) identify critical gaps in the paleoseismic data and recommend where and what kinds of additional paleoseismic studies should be performed to ensure that Utah’s earthquake hazard is adequately documented and understood. It is important to note that, with the exception of the Great Salt Lake fault zone, the Working Group’s review was limited to faults/fault sections having paleoseismic-trenching data. Most Quaternary faults/fault sections in Utah have not been trenched, but many have RI and VSR estimates based on tectonic geomorphology or other non-trench-derived studies. Black and others compiled the RI and VSR data for Utah’s Quaternary faults, both those with and without trenches.

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

The 52 papers in this vary in content from summaries or state-of-knowledge treatments, to detailed contributions that describe new species. Although the distinction is subtle, the title (Vertebrate Paleontology in Utah) indicates the science of paleontology in the state of Utah, rather than the even more ambitious intent if it were given the title “Vertebrate Paleontology of Utah” which would promise an encyclopedic treatment of the subject. The science of vertebrate paleontology in Utah is robust and intense. It has grown prodigiously in the past decade, and promises to continue to grow indefinitely. This research benefits everyone in the state, through Utah’s muse ums and educational institutions, which are the direct beneficiaries.

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.