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This paper describes a small but interesting fauna collected in 1921 by W. T. Thorn, Jr., Gail F. Moulton, T. W. Stanton, and K. C. Heald in the Crow Indian Reservation in southern Montana. The locality is in sec. 36, T. 6 S., R. 32 E., Big Horn County, and is 2 miles east of the Soap Creek oil field.
Although some scientists considered the Ms=7.1 Loma Prieta, Calif., earthquake of 1989 to be an anticipated event, some aspects of the earthquake were surprising. It occurred 17 km beneath the Santa Cruz Mountains along a left-stepping restraining bend in the San Andreas fault system. Rupture on the southwest-dipping fault plane consisted of subequal amounts of right-lateral and reverse motion but did not reach the surface. In the area of maximum uplift, severe shaking and numerous ground cracks occurred along Summit Road and Skyland Ridge, several kilometers south of the main trace of the San Andreas fault. The relatively deep focus of the earthquake, the distribution of ground failure, the absence of throughgoing surface rupture on the San Andreas fault, and the large component of uplift raised several questions about the relation of the 1989 Loma Prieta earthquake to the San Andreas fault: Did the earthquake actually occur on the San Andreas fault? Where exactly is the San Andreas fault in the heavily forested Santa Cruz Mountains, and how does the fault relate to ground ruptures that occurred there in 1989 and 1906? What is the geometry of the San Andreas fault system at depth, and how does it relate to the major crustal blocks identified by geologic mapping? Subsequent geophysical and geologic investigations of crustal structure in the Loma Prieta region have addressed these and other questions about the relation of the earthquake to geologic structures observed in the southern Santa Cruz Mountains. The diverse papers in this chapter cover several topics: geologic mapping of the region, potential- field and electromagnetic modeling of crustal structure, and the velocity structure of the crust and mantle in and below the source region for the earthquake. Although these papers were mostly completed between 1992 and 1997, they provide critical documentation of the crustal structure of the Loma Prieta region. Together, they present a remarkably coherent, three-dimensional picture of the earthquake source region--a geologically complex volume of crust with a long history of both right-lateral faulting and fault-normal compression, thrusting, and uplift.
The basal Cretaceous deposits that fringe the inner margin of the Coastal Plain from eastern Alabama to central North Carolina, where they are overlapped by Miocene sands, have been commonly classified as of Lower Cretaceous age and correlated roughly with the Patuxent formation of the Potomac group of Maryland and Virginia. In this paper the evidence on which this early correlation was based is reviewed, later evidence is considered, and the conclusion is reached that all the basal Cretaceous deposits in the area under consideration are of Upper Cretaceous age. Acknowledgments are gratefully made of the helpful criticism of the manuscript by L. W. Stephenson and of his generous assistance in the preparation of the correlation table.
Problems related to the Belt series have been discussed for nearly a hundred years, but the amount of detailed mapping and other quantitative data available, even now, is not commensurate with the importance of the problem. The present paper is an attempt to summarize existing data in the light of recent fieldwork by the writer and his associates. While the report deals mainly with the rocks in Montana, where the series was first recognized, it necessarily includes consideration of the series in Idaho and parts of Canada as well as of related rocks in more distant areas.
The region in central and northeastern Texas and southern Oklahoma known as the Black and Grand prairies abounds in features of interest to physiographers, geologists, and paleontologists, and the pioneer investigators of this region must have experienced renewed satisfaction in each day's exploration. The reports of Joseph A. Taff, Robert T. Hill, and others, published chiefly under the auspices of State and Federal surveys, represent with approximate accuracy at most places the general distribution of the outcrops of the formations in this region, and contain detailed descriptions of many sections that constitute a mine of useful information. The reader of the present paper is urged, therefore, to hold as most important the general excellence of the earlier reports of these authors and to relegate the inaccuracies and mistakes to which his attention will be called to the relatively unimportant place in which they belong, remembering at the same time that a future generation of investigators may find our own shortcomings as great as those we now criticize.
The field work of which this report is a record was done in the summer and fall of 1921 by members of the United States Geological Survey. A project to build a large storage dam at Lees Ferry, on Colorado River in northern Arizona, called for a detailed topographic survey of the area covered by the project, for the purpose of determining the capacity of the reservoir. This work was undertaken by the United States Geological Survey in cooperation with the Southern California Edison Co. Three surveying parties were sent to the field, each accompanied by a geologist, whose specific duty was to study and report on the rock formations within the area to be flooded. One topographic party, under A. T. Fowler, which started at Lees Ferry and worked up stream in Arizona, was accompanied by Kirk Bryan. Another party, under K. W. Trimble, which started near Bluff and worked down the San Juan and thence down the Colorado, was accompanied by H. D. Miser. The third party, under W. R. Chenoweth, worked from Fremont River to the Waterpocket Fold and then returned to Green River, Utah, and traversed Cataract Canyon during the period of low water. C. R. Longwell was with this party until September, when his place was taken by Sidney Paige. Mr. Paige, in company with the Kolb brothers, E. C. La Rue, and Henry Ranch, left the Chenoweth party after Cataract Canyon had been surveyed and rowed down the Colorado to the mouth of the San Juan, where they were joined by Mr. Miser. Then they took a hurried trip by boat down the Colorado to Lees Ferry, making a few short stops and visiting the famous Rainbow Bridge. Thus the geology of the canyons of Colorado and San Juan rivers and of the lower parts of tributary canyons was examined continuously, and reconnaissance work was done in the country back from the rivers. At the same time a fourth party, under R. C. Moore, was mapping parts of Kane, Garfield, and Wayne counties, Utah, to determine whether oil might be found there. The present paper includes brief descriptions of the rocks of the regions traversed, detailed geologic sections, and columnar sections measured not only by the geologists who accompanied these parties but by other geologists who have worked in the same regions or in adjoining regions. The positions of the columnar sections measured and many of the other sections are shown on Figure 1.
The purpose of this paper is to throw, if possible, some further light on the relations which existed during the later stages of the Glacial epoch between the glaciers of southeastern Wisconsin, which have been so ably discussed by Dr. T.C. Chamberlin and other writers in various publications, and the glaciers of Illinois, which have received such exhaustive treatment by Mr. Frank Leverett in his recent monograph on the Illinois glacial lobe.
The Cumberland Gap coal field lies in Bell and Harlan counties, in the southeast corner of Kentucky and in Claiborne and Campbell counties, Tenn., and extends in a general northeast-southwest direction between Pine and Cumberland mountains from Fork Mountain on the southwest to the heads of Poor and Clover forks of Cumberland River on the northeast. As defined in this paper, it has a total length of about 90 miles and a width of from 15 to 20 miles. (See Pl. II.) In this paper is described only the central part of the basin, or the area lying between Log Mountains at the head of Yell ow Creek of Cumberland and nearly north-south line about 10 miles east of Harlan, and while the data presented will give an idea of the general stratigraphy and structure of the whole field, they are not authoritative except within these limits.
This collection of 39 short papers in the third published chapter of "Geological Survey Research 1971." 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 197, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices.
This paper is an attempt to focus attention on the more important characteristics of the thin-skinned style of deformation in the southern Appalachians by presenting a model to illustrate the regional anatomy and to identify likely structures that need additional investigation as possible prospects for hydrocarbon accumulation. Five distinct changes in color of conodonts were utilized to estimate the oil and gas potential of the Southern Appalachians. Refs.
This collection of 44 short papers is the first published chapter of "Geological Survey Research 1968." The papers report on scientific and economic results of current work by 1ne1nbers of the 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 during fiscal year 1968, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices.
This collection of 40 short papers is the first published chapter of "Geological Survey Research 1969." 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 during fiscal year 1969, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices.
This collection of 38 short papers is the second published chapter of "Geological Survey Research 1969." The papers report on scientific and economic results of current work by members of the 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 during fiscal year 1969, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices.
This collection of 45 short papers is the third published chapter of "Geological Survey Research 1969." The papers report on scientific and economic results of current work by members of the 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 during fiscal year 1969, together with lists of investigations in progress, reports published, cooperating agencies, and Geological Survey offices.
This collection of 12 papers continues the annual series of U.S. Geological Survey (USGS) reports on geologic investigations in Alaska. The annual volume presents results from new or ongoing studies in Alaska that are of interest to scientists in academia, industry, land and resource managers, and the general public. The Geological Studies in Alaska volume reports the results of studies that cover a broad spectrum of earth science topics from many parts of the state (fig. 1). The papers in this volume are organized under the topics Environment and Climate, Resources, and Geologic Framework, in order to reflect the objectives and scope of USGS programs that are currently active in Alaska. Environmental studies are the focus of two articles in this volume: One study addresses the relation between glaciers and aquatic habitat on the Kenai River and another study evaluates the geochemistry of water draining chromite deposits in Alaska. Two papers address mineral resources in southwestern Alaska including a geochemical study of the Fortyseven Creek prospect and a geological and geochemical study of the Stuyahok area. Eight geologic framework studies apply a variety of techniques to a wide range of subjects throughout Alaska, including biostratigraphy, geochemistry, geochronology, paleomagnetism, sedimentology, and tectonics. Two bibliographies at the end of the volume list reports about Alaska in USGS publications released in 1996 and reports about Alaska by USGS authors in non-USGS publications in 1996.
The species cordiforme Meek and Hayden, distans Whitfield, canadense Whiteaves, and dubium Hyatt (probably including whitneyi J. P. Smith), variously assigned to the genera Amaltheus, Quenstediceras, Amoeboceras, and Cardioceras, and subtumidum Whitfield and Hovey, assigned to Aegoceras, include all the previously described species of Jurassic ammonites that are considered in this paper. Material accumulated in the National Museum at Washington, mainly through the efforts of field parties of the United States Geological Survey, has shown, however, the presence of a number of undescribed forms of considerable scientific interest. These new species were obtained mainly from the Sundance formation of Wyoming. One comes from the Ellis formation of Montana, one from Jurassic beds near Lillooet, British Columbia, and three from the Cardioceras-bearing beds near the base of the Naknek formation of Alaska.
The collection of nine papers that follow continue the series of U.S. Geological Survey (USGS) investigative reports in Alaska under the broad umbrella of the geologic sciences. 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 various parts of the State (fig. 1), serving to emphasize the diversity of USGS efforts to meet the Nation's needs for earth-science information in Alaska. The papers in this volume are organized under the topics: Hazards, Geologic Framework, Environment and Climate, and Resources. This organization is intended to reflect the scope and objectives of USGS geologic programs currently active in Alaska. The two Hazards studies discuss volcano-related topics in the seismically active southcentral Alaska region. The first paper revisits the eruptive events of Redoubt Volcano that occurred more than a decade ago and the subsequent development of the Alaska Volcano Observatory (AVO). This treatise documents the historic impact of this eruption and briefly summarizes the state of our knowledge of the other Cook Inlet, Alaska Peninsula, and Aleutian Island volcanoes. Finally, it discusses the recent role that AVO has had in seismic station installation and hazard assessment at volcanically active sites throughout the world. The second paper discusses the eruptive history of Snowy Mountain in the upper Alaska Peninsula. Because subsets of its 25-30 lava flows erupted as packages in short episodes, calculation of the volcano's lifetime average volumetric eruption rate is problematic. A portion of the cone was hydrothermally weakened and collapsed in the late Holocene producing a 22-km2 debris avalanche. Geologic Framework studies provide background information that is the scientific basis for present and future earth science investigations. The first paper compares and contrasts the Insular-Intermontane suture zone (IISZ) of southeast Alaska with the Adria-Europe suture zone (AESZ) of Switzerland and Hungary. The study develops the hypothesis that the zones have distinct differences as well as similarities and neither is a simple lithotectonic terrane boundary. The second paper discusses the relation among volcanic, glacial, and tectonic activity in the Cold Bay and False Pass 1 :250,000-scale quadrangles on the Alaska Peninsula. During Pleistocene time, continental-shelf glaciations and two massive volcanic centers were the dominant controls over landscape development. The third paper gives detailed geologic information for Paleozoic rocks within the Taylor Mountains D-1 quadrangle portion of the Holitna Lowland of southwestern Alaska. Because of the excellent preservation of megafossils, these Silurian and Ordovician strata lend themselves to detailed statigraphic investigations. Further, low thermal alteration indices of this area have made them a potential target of petroleum exploration. The final report in this section discusses the development of a new spectral enhancement approach for interpreting Multispectral Scanner (MSS) and Thematic Mapper (TM) satellite images. This technique enhances the use of remote sensing data in identifying geologic units in areas that have been poorly investigated. This study used this technique to better define the distribution of a JMtu (mafic, ultramafic, and sedimentary) unit and a PzZrqs (pelitic and quartzitic schist) unit. Environment and climate studies are the emphasis of two papers. One presents the first radiocarbon-dated postglacial vegetation history of the Kenai Mountains of southcentral Alaska. This reconstruction is the result of the analysis of pollen assemblages and peat from sediments collected in Tern Lake and presents a minimum age for deglaciation of these interior valleys at 9,31 0±200 yr B .P. Current vegetation, however, developed within the past ca. 2,500 years. A second study discusses the cycling of arsenic and cadmium in sub-arctic boreal forest ecosystems typical of interior Alaska and defines the importance of various natural (geogenic) sources. The transport and uptake into vegetation of these elements from soils developed from loess as well as soils developed from the major rock units is presented. The bioaccumulation of cadmium in willow (Salix sp.) and its potential consequence to the health of browsing animals is discussed. Papers related to resource issues comprise the topic of the final report. This paper presents a brief statistical summary of the geochemistry of rock samples collected in the east-central portion of the Eagle 1 :250,000-scale quadrangle. This study helps define the rock unit source of both resource- and environmental-based chemical elements of interest in the Fortymile mining district. Two bibliographies at the end of the volume list reports covering Alaska earth science topics in USGS publications during 1999 and reports about Alaska by USGS authors in non-USGS publications during the same period.
In a recent paper on the composition of crinoid skeletons we showed that crinoids contain large quantities of magnesia, and that its proportion varies with the temperature of the water in which the creatures live. This result was so novel and surprising that it seemed desirable to examine other echinoderms and to ascertain whether they showed the same characteristics and regularity. A number of sea urchins and starfishes were therefore studied, their inorganic constituents being analyzed in the same manner as those of the crinoids