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At least 235 records · Page 13Linked to original sources

Magma migration and resupply during the 1974 summit eruptions of Kilauea Volcano, Hawaii

The purpose of this paper is to present a complete account of contrasting yet related eruptions, thus filling a gap in the published narratives of recent activity of Kilauea; and to examine their significance within a broader context of regional magmatic and eruptive dynamics. We have gained a historical perspective and can view these three eruptions within a multidecade context of the eruptive behavior of not only Kilauea, but also of the adjacent Mauna Loa.

Professional Paper↗

Geological Survey research 1970, Chapter B

This collection of 46 short papers is the first published chapter of "Geological Survey Research 1970." The papers report on scientific and economic results of current work by members of the Geologic and Water Resources Divisions of the U.S. Geological Survey. Chapter A, to be published later in the year, will present a summary of significant results of work done in fiscal year 1970, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices. "Geological Survey Research 1970" is the eleventh volume of the annual series Geological Survey Research.

Professional Paper↗

Relation of the Wissahickon mica gneiss to the Shenandoah limestone and Octoraro schist of the Doe Run and Avondale region, Chester County, Pennsylvania

The region discussed in this paper lies in Chester County, Pa., and is included in the eastern half of the Coatesville quadrangle. (See fig. 3.) It is within the belt of crystal-line schists and gneisses of the Piedmont Plateau. The northern half of the area, which will be called the Doe Run region, from the village of that name (see Fig. 4, p. 15), has been surveyed by Eleanora F. Bliss in connection with the problem of the relation of the Wissahickon mica gneiss to the Octoraro schist.

Pennsylvania↗

Geologic studies in Alaska by the U.S. Geological Survey, 1998

The 14 papers that follows continue the series of U.S. Geological Survey (USGS) reports on investigations in the geologic sciences in Alaska. The series presents new and sometimes preliminary findings that are of interest to earth scientists in academia, government, and industry; to land and resource managers; and to the general public. Reports presented in Geologic Studies in Alaska cover a broad spectrum of topics from all parts of the State (fig. 1), which serves to emphasize the diversity of USGS efforts to meet the Nation’s needs for earth-science information in Alaska.

Alaska↗

Suggestions for proposing changes in nomenclature in papers submitted to “Stratigraphic Notes”

The “Stratigraphic Notes” series is intended to be an outlet for publication of short papers on stratigraphy, changes in stratigraphic nomenclature, and explanation of stratigraphic names and concepts used on published geologic maps. This report provides authors with suggestions for the content and format of papers submitted to “Stratigraphic Notes” in which geologic names are proposed or their definitions and supporting information are modified. These suggestions are based on the guidance and rules found in the North American Stratigraphic Code (North American Commission on Stratigraphic Nomenclature [NACSN], 2021) and from experience compiling the U.S. Geologic Names Lexicon (Geolex, https://ngmdb.usgs.gov/Geolex/ ). It is with the hope that authors will find these suggestions useful when organizing and presenting their observations and interpretations in a succinct and straightforward fashion, appropriate to “Stratigraphic Notes” (see also, U.S. Geological Survey, 1982, 1984, 1985, 1987, 1991, 1994a, b, 1995). Appendix 1 contains suggested topics and their section headings and subheadings for papers submitted to “Stratigraphic Notes” on new geologic names or changes to names. Within the body of this report, guidance on the content of these sections is provided; for reasons of clarity, suggestions that pertain to changes to formal geologic names are discussed separately from those for proposing new names. Note that, herein, the term “geologic name” is used interchangeably with “geologic unit” and refers to a three-dimensional body of earth material (rock or sediment), recognized by its lithologic content and its boundaries at the surface and (or) subsurface.

Professional Paper↗

A fossil flora from the Frontier formation of southwestern Wyoming

This paper deals with a small but important fossil flora, now known to be of Colorado age, from the vicinity of Cumberland, Lincoln County, Wyo. It was for many years thought to be of Jurassic age, and only within the last decade has its stratigraphic position been established. Although small in number of species, this flora offers information bearing on the physical and climatic conditions that prevailed during early Upper Cretaceous time in this region, and, moreover, it furnishes a series of stratigraphic marks that may be used in the recognition of this horizon elsewhere.

Wyoming↗

Brachyceratops, a ceratopsian dinosaur from the Two Medicine formation of Montana, with notes on associated fossil reptiles

The fossils on which this paper is based were collected by me and my assistant, Mr. J. F. Strayrer, during the summer of 1913, while working under the auspices of the United States Geological Survey on the Blackfeet Indian Reservation, in northwestern Montana. The specimens were obtained from exposures of the Two Medicine formation along Milk River near the Canadian boundary, in T. 37 N., R. 8 W., about 30 miles northwest of the town of Cut Bank, Mont., and along Two Medicine River in T. 31 N., R. 7 W., about 15 miles southwest of Cut Bank. Vertebrate remains were found at these places in, 1911 and 1912 by Eugene Stebinger, while he was engaged in Geological Survey work, and he was the first to note that the localities are good fields for finding specimens of fossil vertebrates. 2 Although the present collection is small, it is of considerable scientific interest because it supplements the collections made in neighboring areas by other investigators, and because it contains a new genus of Ceratopsia in addition to other recognizable specimens which afford evidence that considerably extends the geologic and geographic ranges of forms heretofore described. The beds from which the collection was made constitute the upper part of the Two Medicine formation, which includes the equivalent of the Judith River formation and some older beds. The fossiliferous beds are also the equivalent of the upper part of the Belly River formation as found in neighboring areas of Canada. The fauna of the American Judith River formation, although diversified, is very inadequately known. Many of the genera and species have been founded on specimens so scant and fragmentary that it is almost impossible to refer to them subsequently discovered and more perfect materials. Recent collections made by L. M. Lambe, of the Canada Geological Survey, and by Barnum Brown, of the American Museum of Natural History, from the Belly River formation along Red Deer River in Canada, however, have placed this fauna on a more solid basis. The purpose of this paper is to give as complete and detailed a description of the skeletal anatomy of Brachyceratops montanensis as the material at hand will permit and to discuss briefly, in systematic order, other forms represented by specimens in the collection made in 1913. I take this opportunity to express my thanks for assistance rendered and for courtesies extended at many times, both in the field and during the preparation of this report, by Messrs. M. R. Campbell, T. W. Stanton, and F. H. Knowlton, and especially by Mr. Eugene Stebinger, all of the United States Geological Survey.

Montana↗

Geological Survey research 1972, Chapter C

This collection of 37 short papers is the second published chapter of "Geological Survey Research 1972." The papers report on scientific and economic results of current work by members of the Conservation, Geologic, and Water Resources Divisions of the U.S. Geological Survey. Chapter A, to be published later in the year, will present a summary of significant results of work done ~n fiscal year 1972, together with lists of investigations in progress, cooperating agencies, and Geological Survey offices. "Geological Survey Research 1972" is the thirteenth volume of the annual series Geological Survey Research. The twelve volumes already published are listed below, with their series designations.

Professional Paper↗

Geological Survey research 1970, Chapter D

This collection of 45 short papers is the third published chapter of "Geological Survey Research 1970." The papers report on scientific and economic results of current work by members of the Geologic, Water Resources, and Topographic Divisions of the U.S. Geological Survey. Chapter A, to be published later in the year, will present a summary of significant results of work done in fiscal year 1970, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices. "Geological Survey Research 1970" is the eleventh volume of the annual series Geological Survey Research. The ten volumes already published are listed below, with their series designations.

Professional Paper↗

Geological Survey research 1970, Chapter C

This collection of 42 short papers is the second published chapter of "Geological Survey Research 1970." The papers report on scientific and economic results of current work by 1nembers of the Conservation, Geologic, Topographic, and Water Resources Divisions of the U.S. Geological Survey. Chapter A, to be published later in the year, will present a summary of significant results of work done in fiscal year 1970, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices. "Geological Survey Research 1970" is the eleventh volume of the annual series Geological Survey Research. The ten volumes already published are listed below, with their series designations.

Professional Paper↗

Some of Alpheus Hyatt's unfigured types from the Jurassic of California

Alpheus Hyatt named a considerable number of Jurassic fossils from California. Only a few of these were described, arid none were illustrated. In this paper 16 of these species are evaluated in terms of present-day nomenclature, figures of the type specimens are shown, and their probable age significance is given. Included are Monotis semiplicata (=Entolium semiplicata),Monotis symmetrica (=Entolium symmetrica), Daonella?subjecta ( = '' Daonella" subjecta), Daonella bOchiformts (=" Daonella" bOchiformis), Daonella cardinoides (="Duonella"cardinoides), A ucella erringtoni var. arcuata ( = Buchia arcuata), Aucella elongata ( = Buchia elongata), AuceUa var.elongata orbicularis ( = Buchia sinzovi), Aucella aviculaeformis ( = Buchia erringtoni var. aviculaeformis), Aucella aviculaeformis var. acuta ( = Buchia erringtoni var. orbicularis), Aucella orb·.icularis( = Buchia erringtoni var. orbicularis), Cardioceras dub\~um ( = Amoeboceras dubium), Perisphinctes virgulatiformis ( = Viigatosphinctes virgulatiformis), Perisphinctes miihlbachi ( = Dichotomoceras miihlbachi), iJlcostephanus lindgreni ( =" Galilaeiceras" lindgreni), Oecotraustes denticulata ( = "Oecotraustes" dent-iculata).

California↗

Stratigraphy, paleoflora, and tectonic setting of the Paleogene Sheep Creek volcanic field, central Alaska

In this paper, we provide new information on the stratigraphy and paleoflora of the Sheep Creek volcanic field in the Alaska Range that bolsters our understanding of a key interval in the tectonic, paleoclimate, and paleoenvironmental history of the northern Cordillera. Although the distribution and basic stratigraphy of these rocks have been previously reported, here we document the stratigraphic context of recently dated igneous rocks and paleosols ranging from the Paleocene–Eocene boundary to the early middle Eocene, describe a more complete fossil leaf flora from the succession, and place the Sheep Creek volcanic field in its regional tectonic context of ridge subduction and slab window migration in central Alaska.

Alaska↗

Shorter contributions to general geology, 1929

Thin beds that consist almost wholly of euhedral analcite crystals occur at five or more horizons in the upper half of the Green River formation of Utah and Colorado, a series of Eocene lake beds that contain large deposits of oil shale. Most of these beds contain also minute crystals of apophyllite. The analcite crystals in some beds are cemented only by chalcedony, but in other beds that have less analcite the matrix is tuffaceous and consists of chalcedony in which are embedded splinters of feldspar, hornblende, and quartz, laths of biotite, and euhedral crystals of sanidine, apatite, and zircon. Analcite occurs plentifully also, disseminated in many of the oil-shale beds, and locally makes up as much as 16 per cent of weight of the rock. In these beds the analcite is accompanied by apophyllite, euhedral crystals of sanidine and orthoclase, angular fragments of quartz, and a little volcanic glass. The rocks associated with the beds of analcite and analcite-bearing oil shale contain salt-crystal cavities, that strongly suggest the former presence of glauberite and anhydrite. Both clastic and hydrothermal hypotheses for the origin of the zeolites are considered and dismissed in the paper. The field and microscopic evidence presented leads to the conclusion that all the analcite and apophyllite formed in place on the lake bottom as a result of interactions between salts dissolved in the lake water and the dissolution products of volcanic ash that fell into the lake. Meerschaum, or fibrous sepiolite, occurs in several thin beds near the top of the Green River formation in Duchesne County, Utah. It is mixed with structureless organic matter like that in the oil shale and apparently formed in place on the lake bottom. Chemical analyses of the analcite rock and of the sepiolite are given.

Professional Paper↗

The Tertiary and Quaternary pectens of California

This paper consists of two parts. The first is a brief outline of the different Tertiary and Pleistocene formations of California, giving the type localities, where, when, and by whom first described, their salient characters, where they and their supposed equiyalents are known to occur, the species of Pecten found in them, and their typical fauna as far as known. The second is devoted to the description and illustration of all of the known Tertiary, Pleistocene, and Recent Pectens of the western coast of North America from Alaska to and including the Gulf of California. With the description of each species is also given an account of its geologic and geographic range and, where practicable, its associated fauna.

California↗

The molluscan fauna of the Alum Bluff group of Florida, Part II, Astartacea, Carditacea, Chamacea

The first of the series of papers upon the Mollusca of the Alum Bluff group covered the orders of the Prionodesmacea and the Anomalodesmacea. The Mollusca were by the beginning of Miocene time so far advances in development that the great majority are included under the highest of the three orders, the Teleodesmacea, characterized in the adult stages by the differentiation of the hinge teeth into distinct cardinals and laterals. This paper, the second of the series, covers the most primitive of the Teleodesmacea in the Alum Bluff group. All three of the superfamilies considered - the Astartacea, the Carditaeea, and the Chamacea-are included under Dall's group of the Diogenodonta, which is characterized in the normal forms by one or two laterals and not more than three cardinals. The Carditacea are very closely related to the Astartacea in hinge armature but differ in the development of a pronounced radial sculpture. The Chamacea have until recently been considered an offshooting group from the Carditacea that have been greatly modified by their sessile habit. Some doubt has been thrown upon this relationship by the late morphologic studies of Odhner.

Florida↗

The Loma Prieta, California, Earthquake of October 17, 1989: Forecasts

The magnitude (Mw) 6.9 Loma Prieta earthquake struck the San Francisco Bay region of central California at 5:04 p.m. P.d.t. on October 17, 1989, killing 62 people and generating billions of dollars in property damage. Scientists were not surprised by the occurrence of a destructive earthquake in this region and had, in fact, been attempting to forecast the location of the next large earthquake in the San Francisco Bay region for decades. This paper summarizes more than 20 scientifically based forecasts made before the 1989 Loma Prieta earthquake for a large earthquake that might occur in the Loma Prieta area. The forecasts geographically closest to the actual earthquake primarily consisted of right-lateral strike-slip motion on the San Andreas Fault northwest of San Juan Bautista. Several of the forecasts did encompass the magnitude of the actual earthquake, and at least one approximately encompassed the along-strike rupture length. The 1989 Loma Prieta earthquake differed from most of the forecasted events in two ways: (1) it occurred with considerable dip-slip in addition to strike-slip motion, and (2) it was much deeper than expected.

California↗

Geologic studies in Alaska by the U.S. Geological Survey, 1995

This collection of 20 papers continues the annual series of U.S. Geological Survey (USGS) reports on geologic investigations in Alaska1 . Contributions cover a broad spectrum of earth science topics and report results from all parts of the State (fig. 1). USGS activities in Alaska include studies of environment and climate, hazards, resources, and geologic framework. Five papers in this volume discuss aspects of environment and climate. Environmental geochemistry of parts of southwestern and south-central Alaska is the focus of four articles; a fifth study, of emergent postglacial lake shorelines in southwestern Alaska, contributes to ongoing investigations of paleoclimate. Two papers address geologic hazards. The first assesses ground deformation in Katmai National Park at Novarupta dome, site of the largest volcanic eruption in this century, and the second evaluates earthquake risks related to the "Twin Peak fault" near Anchorage. Resources, including metallic minerals in northern, southwestern, and southeastern Alaska and coal in south-central Alaska, are discussed in four articles. Nine geologic framework studies apply a variety of techniques to a wide range of subjects throughout Alaska, including tectonics, geophysics, geochronology, bio stratigraphy, sedimentology, paleogeography, and paleomagnetism. Two bibliographies at the end of the volume list reports about Alaska in USGS publications released in 1995 and reports about Alaska by USGS authors in non-USGS publications in 1995.

Alaska↗

Geochronology and geology of late Oligocene through Miocene volcanism and mineralization in the western San Juan Mountains, Colorado

This paper presents 25 new 40Ar/39Ar dates from the main calc-alkaline ash-flow sheets and related younger plutons of the western San Juan volcanic field, the ash-flow sheets of the Lake City caldera cycle, and veins and other altered rocks in the Lake City region. The goal of the study was to produce similar quality 40Ar/39Ar ages to those currently published for the eastern and central San Juan Mountains. These new data provide a much more precise chronological framework for interpreting durations of events and their relationship to mineralization than do previously published conventional K-Ar dates for the western San Juan Mountains.

Professional Paper↗