"This volume is the product of nearly 25 years of geologic investigations. It is an exposition of two small areas, both less than 25 km from the front of the Mississippian Roberts Mountains thrust, but each displaying a different, unique geologic terrane, previously undocumented in Nevada and perhaps in North America"--

The geological and palaeontological records of climate change and evolutionary events reflect Earth’s widely fluctuating climate systems. Past climates hold the clues to understanding future developments. In this context, research on linked climate, biodiversity and sea-level fluctuations of the Devonian contributes to the general knowledge of deep-time climate dynamics. A fruitful co-operation between the International Geoscience Programme IGCP 596 and the International Subcommission on Devonian Stratigraphy (SDS) addressed the complex succession of climate-linked Devonian global events of varying magnitude. The primary goal of IGCP 596 was to assess mid-Palaeozoic climate changes and their impact on marine and terrestrial biodiversity using an interdisciplinary approach. The focus of SDS includes a revision of the eustatic sea-level curve and the integration of refined chrono- and biostratigraphy with modern chemo-, magneto-, cyclo-, event- and sequence stratigraphy. This enabled the much improved dating and correlation of abiotic perturbations, evolutionary changes, organism and ecosystem ranges. Results by 37 authors are presented in 14 chapters, which cover the entire Devonian.

A great volume of Mississippian orogenic deposits supports the concept of a mid-Paleozoic orogeny in Nevada, and the existence and timing of that event are not questioned here. The nature of the orogeny is problematic, however, and new ideas are called for. The cause of the Antler orogeny, long ascribed to plate convergence, is here attributed to left-lateral north-south strike-slip faulting in northwestern Nevada. The stratigraphic evidence originally provided in support of an associated regional thrust fault, the Roberts Mountains thrust, is now known to be invalid, and abundant, detailed map evidence testifies to post-Antler ages of virtually all large folds and thrust faults in the region. The Antler orogeny was not characterized by obduction of the Roberts Mountains allochthon; rocks composing the "allochthon" essentially were deposited in situ. Instead, the orogeny was characterized by appearance of an elongate north-northeast-trending uplift through central Nevada and by two parallel flanking depressions. The eastern depression was the Antler foreland trough, into which sediments flowed from both east and west in the Mississippian. The western depression was the Antler hinterland trough into which sediments also flowed from both east and west during the Mississippian. West of the hinterland trough, across a left-lateral strike-slip fault, an exotic landmass originally attached to the northwestern part of the North American continent was moved southward 1700 km along a strike-slip fault. An array of isolated blocks of shelf carbonate rocks, long thought to be autochthonous exposures in windows of the Roberts Mountains allochthon, is proposed here as an array of gravity-driven slide blocks dislodged from the shelf, probably initiated by the Late Devonian Alamo impact event.

The 2004 NPS field trip concentrates on breccias in the Great Basin. Breccias are significant reservoirs in many petroleum basins worldwide. The oil production at Eagle Springs, Nevada's first field, and in one of the states newest fields, Ghost Ranch, apparently comes from a landslide breccia. The Great Basin breccias are of three types. The first is impact breccias. Dr. John Warme and his colleagues from the Colorado School of Mines and the United State Geological Survey have compiled a substantial amount of evidence to confirm that an extraterrestrial impact occurred during deposition of the Middle Devonian Guilmette Formation. The effects of this collision can be seen over a wide area in Nye and Lincoln Counties. The breccia, named the Alamo Breccia, should provide an exceptional time line for correlations within that area. Additionally, the single graded bed might be a significant reservoir as well.The second type of potential reservoir is the collapse breccias developed during paleokarsting and paleocave development. Like the Alamo Breccia, the collapse breccias also occur in the Devonian Guilmette Formation. To date, the collapse breccias have been identified in northern Nye County and southern Eureka and White Pine Counties and are probably related to a forebulge developed by the Antler Orogeny. Should the associated paleocaves be open in the subsurface and oil filled, they could have astounding production potential like those of the fields in west Texas.The last type of Great Basin breccia to be considered is landslide breccias. These are not "potential reservoirs" but are actual features that can be found in both Eagle Springs and Ghost Ranch Fields. Like the previous two types, these also involve the Devonian Guilmette Formation as well as the Pennsylvanian Ely Limestone. As such, they are real, proven exploration targets in the Great Basin.