Sixty fusulinid species, 17 of which are newly named, are herein described from the Lower Permian part of the Owens Valley Group in east-central California. These consist of 2 species of Triticites , 1 of Leptotriticites , 16 of Schwagerina , 1 of Pseudofusulina , 3 of Chusenella , 1 of Paraschwagerina , 9 of Stewartina , 6 of Pseudoschwagerina , 3 of Chalaroschwagerina , 6 of Cuniculinella , 3 of Eoparafusulina , and 6 of Parafusulina . In addition, a new genus, Reticulosepta (with three species), is described. The fusulinid fauna of the Owens Valley Group contains some elements of the Pseudoschwagerina association of the Texas-Cordilleran region and a few species similar to those of the Chalaroschwagerina association of the eastern Klamath Mountains. In addition, several species apparently are endemic. Most of the fusulinids are from sediment-gravity-flow deposits in which there was apparently a great deal of mixing of faunas from different coexistent environments. In general, however, there is little evidence of mixing through reworking of older faunas, which has allowed biostratigraphic subdivision of the Lower Permian part of the Owens Valley Group based on fusulinids. The subunits recognized—lower Wolfcampian, middle Wolfcampian, upper Wolfcampian, and Leonardian—are comparable to subunits of the Lower Permian based on fusulinids in other parts of North America.

ABSTRACT The Sierra Nevada batholith of California represents the intrusive footprint of composite Mesozoic Cordilleran arcs built through pre-Mesozoic strata exposed in isolated pendants. Neoproterozoic to Permian strata, which formed the prebatholithic framework of the Sierran arc, were emplaced against the tectonically reorganized SW Laurentian continental margin in the late Paleozoic, culminating with final collapse of the fringing McCloud arc against SW Laurentia. Synthesis of 22 new and 135 existing detrital zircon U/Pb geochronology sample analyses clarifies the provenance, affinity, and history of Sierra Nevada framework rocks. Framework strata comprise terranes with distinct postdepositional histories and detrital zircon provenance that form three broad groups: allochthonous Neoproterozoic to lower Paleozoic strata with interpreted sediment sources from Idaho to northern British Columbia; Neoproterozoic to Permian strata parautochthonous to SW Laurentia; and middle to upper Paleozoic deposits related to the fringing McCloud arc. Only three sedimentary packages potentially contain detritus from rocks exotic to western Laurentia: the Sierra City mélange, chert-argillite unit, and Twin Lakes assemblage. We reject previous correlations of eastern Sierra Nevada strata with the Roberts Mountains and Golconda allochthons and find no evidence that these allochthons ever extended westward across Owens Valley. Snow Lake terrane detrital ages are consistent with interpreted provenance over a wide range from the Mojave Desert to central Idaho. The composite detrital zircon population of all analyses from pre-Mesozoic Sierran framework rocks is indistinguishable from that of the Neoproterozoic to Permian SW Laurentian margin, providing a strong link, in aggregate, between these strata and western Laurentia. These findings support interpretations that the Sierran arc was built into thick sediments underpinned by transitional to continental western Laurentian lithosphere. Thus, the Mesozoic Sierra Nevada arc is native to the SW Cordilleran margin, with the Sierran framework emplaced along SW Laurentia prior to Permian–Triassic initiation of Cordilleran arc activity.

INTRODUCTION To trace fully and in chronological sequence the development of ideas concerning the origin of the lead and zinc ores of the Mississippi Valley region would be of considerable historic interest but a task of discouraging magnitude. It is fortunate, therefore, that the concepts of genesis, though varying much in detail, lend themselves to a grouping in two major categories: (1) The meteoric hypotheses, and (2) the magmatic hypothesis. In the following summary chronology and the crediting of ideas to their ultimate source will be subordinated to simplicity and brevity of treatment. As pointed out by Shepard (1898, p. 169–170), the earlier geologists, including Schoolcraft, Featherstonhaugh, Swallow, Owen, and Percival, being familiar mainly with the more steeply inclined vein-like occurrences, were almost unanimous in attributing the mineralization to ascending solutions from deep-seated sources. With the discovery and development of the great blanket deposits which gave little or no evidence of extension to considerable depths, the concept of leaching of the metals from sparse disseminations in the country rocks and concentration in their present location by meteoric waters became the dominant view and was presented in the reports of T. C. Chamberlin, Winslow, Bain, Van Hise, Buckley, Buehler, Grant, Siebenthal, Cox, and others. Shepard and Jenney were notable dissenters from this view. Of recent years, as a consequence of the mounting volume of evidence indicating that the majority of metalliferous deposits were deposited by solutions from magmatic sources and as a consequence of the discovery of numerous though scattered . . .

Abstract New Harmony, Indiana, has an important place in the history of geology for North America. David Dale Owen, son of Robert Owen, who had attempted to establish a communal society in New Harmony, developed an impressive geological enterprise there. D.D. Owen's work included geological training at his New Harmony laboratories and the first geological mapping expeditions for many states and districts in the expanding United States. He served as the first state geologist for Indiana, a position also held by his brother, Richard. Several scientific notables, including William Maclure, Charles Lyell, Thomas Say, and others visited and studied natural history while based in New Harmony. The famous "Boatload of Knowledge" brought several artists, teachers, scientists, and other intellectuals to their new home in New Harmony, Indiana. Our trip to some of the original sites in this important town, including D.D. Owen's geological laboratories and Maclure's Working Men's Institute, will take us through the characteristic southwestern Indiana landscape of glacial-meltwater-lake plains, loess mantled bedrock uplands, and the Ohio and Wabash River valleys.

The North American Great Basin is a useful venue for the study of dispersal, vicariance, and rates of molecular evolution among aquatic organisms because its Pleistocene hydrogeographic history is relatively well known. This study examines regional molecular variation in the amphipod Hyalella azteca using mitochondrial (mt) gene sequence (deoxyribonucleic acid [DNA]) data. Populations within several endorheic drainages in the southern Great Basin were analyzed to determine if they represent a monophyletic assemblage with respect to populations from the pluvial Lake Bonneville drainage in the northern Great Basin. We also tested whether the patterns of molecular diversification among populations in the southern Great Basin were consistent with a Pleistocene vicariance hypothesis, and if the magnitude of observed sequence divergence was concordant with standard molecular clock calibrations. Our results show that diversity and endemism among Hyalella populations in the southern Great Basin are high with respect to those in the Lake Bonneville Basin. We further demonstrate that hyalellid populations in the southern Great Basin are a polyphyletic assemblage with respect to their counterparts in the Bonneville Basin, suggesting that dispersal events have been partially responsible for the enigmatic relationships within this assemblage. The relationships among lineages within the southern Great Basin are largely enigmatic and are not concordant with Pleistocene hydrographic history. Our data also indicate that rates of molecular evolution have been heterogeneous; there is a 2.8-fold disparity in relative rates of mtDNA divergence among closely allied lineages. The magnitude of sequence divergence among lineages is inconsistent with standard molecular clock calibrations, and evidence indicates that accelerated rates of divergence may have contributed to the high diversity and endemism among Great Basin hyalellids, complicating reconstruction of the temporal sequence of biogeographic events.

Abstract The eastern California shear zone is an important component of the Pacific–North America plate boundary. This region of active, predominantly strike-slip, deformation east of the San Andreas fault extends from the southern Mojave Desert along the east side of the Sierra Nevada and into western Nevada. The eastern California shear zone is thought to accommodate nearly a quarter of relative plate motion between the Pacific and North America plates. Recent studies in the region, utilizing innovative methods ranging from cosmogenic nuclide geochronology, airborne laser swath mapping, and ground penetrating radar to geologic mapping, geochemistry, and U-Pb, 40 Ar/ 39 Ar, and (U-Th)/He geochronology, are helping elucidate slip rate and displacement histories for many of the major structures that comprise the eastern California shear zone. This field trip includes twelve stops along the Lenwood, Garlock, Owens Valley, and Fish Lake Valley faults, which are some of the primary focus areas for new research. Trip participants will explore a rich record of the spatial and temporal evolution of the eastern California shear zone from 83 Ma to the late Holocene through observations of offset alluvial deposits, lava flows, key stratigraphic markers, and igneous intrusions, all of which are deformed as a result of recurring seismic activity. Discussion will focus on the constancy (or non-constancy) of strain accumulation and release, the function of the Garlock fault in accommodating deformation in the region, total cumulative displacement and timing of offset on faults, the various techniques used to determine fault displacements and slip rates, and the role of the eastern California shear zone as a nascent segment of the Pacific–North America plate boundary.

ABSTRACT The historic town of New Harmony is located along the Wabash River in Posey County, Indiana, and served as a focal point for natural scientists, especially geologists, in the early nineteenth century. Notable geologists that lived and worked in New Harmony during this time include Edward Travers Cox, William Maclure, Fielding Bradford Meek, Joseph Granville Norwood, David Dale Owen, Richard Dale Owen, Benjamin Franklin Shumard, Gerard Troost, and Amos Henry Worthen. Other natural scientists who worked in New Harmony include Charles Alexandre Lesueur and Thomas Say, and the town was also visited by James Hall, Leo Lesquereux, Sir Charles Lyell, and Alexander Philipp Maximilian, Prince of Wied. The purpose of this field-trip guide is to highlight the scientific and geologic enterprise that operated in nineteenth-century New Harmony, Indiana. There will be a tour of historic buildings including laboratories used by David Dale Owen, such as the Rapp-Owen Granary and his fourth laboratory, which was constructed in 1859. Furthermore, field-trip participants will visit a new geology exhibit at the Working Men’s Institute, an organization established by William Maclure in 1838. The field excursion will also visit historically significant localities, including Mississippian and Pennsylvanian exposures, the type section of the West Franklin Limestone, and a Pennsylvanian paleobotanical site that yielded extensive collections of plant fossils in the mid-nineteenth century. Finally, this field trip will provide an opportunity to discuss the importance of art to geological studies in the early nineteenth century. Specifically, hand-colored geologic maps, cross sections, and renderings of fossils were included with many of the scientific reports of historic New Harmony, and are reflected by the superb artwork of Charles Alexandre Lesueur, David Dale Owen, and Thomas Say. Access to view their original scientific artwork is possible only through special arrangement with the Working Men’s Institute.