bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic exploration of the crust and upper mantle of the Basin and Range province
Authors: Pakiser L. C. 
Published: April 2015

Abstract
The fundamental features of the seismic-velocity structure of the crust of the Basin and Range province have been known for 30 years. Tatel and Tuve (1955) expressed surprise in finding that the crust is only 28–34 km thick in the Basin and Range/Colorado Plateau transition zone of Arizona, New Mexico, and Utah. From isostatic considerations they had expected the crust of this elevated region to be about 70 km thick. Carder and Bailey (1958) obtained similar results in the Basin and Range province in the vicinity of the Nevada Test Site. Later, Press (1960), Berg and others (1960), and Diment and others (1961) discovered the characteristic low velocity of the upper mantle of the province, although they regarded the 7.6–7.8 km/sec velocities they found at depths of 24–28 km as possibly too low for the upper mantle. Nevertheless, the unexpectedly thin crust and low-velocity upper mantle have been accepted by most investigators as characteristic features of the Basin and Range province since U.S. Geological Survey seismic teams demonstrated that the discontinuity below which the velocity is about 7.8 km/sec is the most prominent one in the province and argued that it should be regarded as the Mohorovičé discontinuity (Pakiser, 1963).
Our knowledge of the gross features of the crustal and upper-mantle structure of the Basin and Range province has changed little in the past 20 years, but many important details have been added. Major problems, however, remain to be resolved. Reexamination of the evidence for extremely low upper-mantle velocities in the vicinity of the Wasatch front (Smith, 1978) suggests that velocities there may not be very different from those in other parts of the province. New, more nearly definitive seismic-refraction and -reflection experiments and reanalysis of existing data using new analytical techniques will be required to resolve such problems.
A basement of melanges
Authors: Hsü Kenneth J. 
Published: April 2015

Abstract
The Franciscan of the California Coast Ranges was considered a lithostratigraphic unit (a formation or group of formations) for more than a century. Normal stratigraphical methodology was practised, and few questioned the applicability of the laws of superposition, lateral continuity, and paleontological dating. Despite evidence to the contrary, researchers portrayed deformation of coherent strata. Metamorphic conditions were deduced on the basis of presumed field relations, and the geosynclinal theory of mountain building was the paradigm. A subjective choice of data allowed researchers to fit the Franciscan into a straight-jacket, and for many years it was described as a Late Jurassic Tithonian formation, deposited in a eugeosyncline on the western margin of the North American continent after the Nevadan Orogeny.
The classical model failed to take into account a number of key observations that challenged accepted beliefs. Micropaleontological evidence for the Cretaceous age of some Franciscan rocks was known but not taken seriously. Finally, however, the discovery of an ammonite of undoubted Cretaceous age in a Franciscan sandstone at the type locality led to a crisis. It became impossible to ignore mounting evidence that the Franciscan contains rocks coeval to the Great Valley Sequence, which ranges in age from Tithonian to Late Cretaceous, despite the fact that rocks of typical Franciscan lithology (e.g., ophiolites) underlie the Knoxville and should therefore be older than the Great Valley Sequence.
The application of the mélange concept and the assumption of underthrusting resolved the Franciscan-Knoxville Paradox, and resulted in a revolutionary change in our thinking on Franciscan geology. At about the same time, a new paradigm in geology, the new plate-tectonic theory, was introduced. With plate tectonics, crises could be overcome, contradictions eliminated, and a period of “normal science” could prevail.
Franciscan research went through five stages: 1) random observations; 2) synthesis; 3) crisis; 4) revolution, or overthrow of the old paradigm and establishment of the new; and 5) mopping up. A history of the process illustrates the theory of scientific revolution advocated by Thomas Kuhn.
The Coon Butte Crater controversy
Authors: Drake Ellen T. 
Published: April 2015

Abstract
G. K. Gilbert's (1891) first assessment of the crater at Coon Butte, Arizona (now called Meteor Crater), was that it was caused by a meteorite impact. His classical paper The Moon's Face (1893) eloquently argued for the impact hypothesis to explain lunar craters. But by 1896 he had changed his mind on the Coon Butte Crater, as he could not find the “buried star,” even though several tons of meteoritic material had been found in the area. The steam explosion explanation, suggested to him by Willard D. Johnson and tentatively adopted by Gilbert, then became the accepted hypothesis for the origin of Coon Butte Crater among most geologists. In spite of a great deal of evidence for the impact idea, the steam explosion explanation, with the exception of a few notable individuals, took root in the geological community, much to the frustration of D. M. Barringer. The latter insisted on the existence of the “main mass” of the meteorite and spent a lifetime and fortune attempting to prove the impact origin of the crater by looking for the meteoritic body. He also had visions of a lucrative mining adventure. Barringer opposed G. P. Merrill, a distinguished scientist within the geological community, who supported the impact idea but explained the absence of a “main mass” of meteoritic material by its volatilization. The modem explanation for the creation of the crater is by shock waves produced from the dissipation of kinetic energy of the meteorite travelling at hypervelocity.
Several reasons might explain the long delay in acceptance of the impact hypothesis: (1) in the absence of more evidence, the geological community naturally followed the lead of the much-admired Gilbert; (2) to the geologists, Barringer and his associates were outsiders, rich and respected men in other fields and in industry, but not in geology and therefore could be ignored; (3) Barringer was “ahead of his time,” and therefore could not expect much support from his contemporaries. The reasons were probably multiple and complex and may involve fundamental philosophical concepts. For example, as Eugene Shoemaker (1984) suggested, geologists were so imbued with Lyellian uniformitarianism that they could not accept a catastrophic explanation, i.e., the fall of an extra-terrestrial object causing the creation of a terrestrial feature. It is not clear, however, that any one answer explains the puzzle. The Coon Butte Crater controversy also tests two other ideas much touted by geologists, the principle of multiple working hypotheses and the idea of tolerance for unorthodoxy in science. Both concepts seemed to have failed the test.
Development of quantitative geomorphology
Authors: Morisawa Marie 
Published: April 2015

Abstract
Despite numerous precursors, real quantification in geomorphology did not take hold until after Horton's (1945) paper outlining a new approach to the study of drainage basins. The use of quantitative methods in landform analysis has varied for different geomorphic processes.
Quantitative studies in weathering have been done mostly in the fields of geochemistry, pedology, and soil mechanics. Little has been done to quantify weathering forms. Quantitative analyses on slopes and mass movements have included both processes and morphology, leading to geometric and mathematical models. In contrast, quantitative analyses of arid regions and aeolian forms and processes are immature and tentative. Although great strides have been taken in using physics and mathematics for understanding glacier flow, little has been done on morphometry of glacial landforms. Progress in quantitative coastal research has been most rapid since World War II, although the mathematical basis for understanding coastal processes was laid in the 19th century. As a result of Horton's (1945) provocative study, fluvial geommorphology has perhaps made the most advances in quantitative analyses in geomorphology.
The infusion of ideas from physics, chemistry, biology, engineering, pedology, soil mechanics, hydraulics, hydrology, and geography and the application of statistics and mathematics in analysis accomplished the quantitative revolution. In addition to changing techniques of analysis, quantification has altered the fundamental approach to the study of landforms and affected basic concepts. The dynamic approach (Strahler, 1952) became focused on process and mechanics rather than history and description. Landscape units are treated as open systems in equilibrium where any change in the system causes an adjustment to offset effects of the change.
Electronic instrumentation, remote sensing, and advanced methods of data processing and storage by high-tech computers will open even more vistas for exploration by quantitative geomorphologists of the future.
Canadian Shield
Authors: Shilts William W. , Aylsworth Janice M. , Kaszycki Christine A. , Klassen Rodney A. 
Published: April 2015

Abstract
The Canadian Shield* (Fig. 1) is a geologically complex terrain that makes up about one-third of the North American landmass. Its rocks were deposited, formed, and deformed over a time span encompassing about three-quarters of the earth’s known geologic history. Consequently, it includes lithologies, structural elements, and topography as varied as those found on the North American continent as a whole. Because of the complexity of geomorphic features that reflect this geologic diversity, we have decided to focus this chapter on the most obvious geomorphologic elements of its modern landscape, the various landforms produced by the latest geologic events to affect the area, the Pleistocene glaciation. Virtually all of the distinctive landscape elements commonly associated with the Canadian Shield were formed or noticeably modified as a result of the passage of glaciers that coalesced to form the last great continental ice mass, the Laurentide Ice Sheet (Prest, 1970).
Before discussing the glacial geomorphology of the Shield, it is appropriate to make some general observations of the geologic factors that have influenced the nature and distribution of glacial landforms and sediments. Because of the antiquity of the rocks that comprise this “stable” core of the continent, original lithologies have been modified by numerous orogenic and metamorphic events as the earth’s crust evolved and as crustal elements shifted through the agency of plate tectonics. The composition of the oldest rocks, in fact, reflects both sedimentation in a primitive, pre-oxygen atmosphere and igneous events that took place as the
Great Plains
Authors: Osterkamp Waite R. , Fenton Mark M. , Gustavson Thomas C. , Hadley Richard F. , Holliday Vance T. , Morrison Roger B. , Toy Terrence J. 
Published: April 2015

Abstract
The Great Plains Physiographic Province (Fig. 1) is a generally north-south band of the western interior of North America, subcontinental in scale, that averages about 600 km in width and extends from northwestern Canada through the United States to the border with Mexico. With tongue-in-cheek, Thornbury (1965, p. 287) claimed that “in the public mind the Great Plains are thought of as a vast monotonous plain that lacks scenic interest, but has to be crossed to reach the scenic Rocky Mountains to the west.” It is generally true that the Great Plains, and especially the High Plains, have low relief. But there are many scenic exceptions, largely areas of negative relief along the eroded margins of the plains and in river valleys. Areas of positive relief include structural highs such as the Black Hills (Fig. IB) and other outliers of the Rocky Mountains. These areas of positive and negative relief are especially important, because they contain the sections where the geologic and geomorphic history of the Great Plains is best exposed.
Rocky Mountains
Authors: Madole Richard F. , Bradley William C. , Loewenherz Deborah S. , Ritter Dale F. , Rutter Nathaniel W. , Thorn Colin E. 
Published: April 2015

Abstract
The Rocky Mountain region is one of the most topographically distinct and impressive parts of North America. The Rocky Mountains rise abruptly above the bordering regions, particularly on the east and northeast where they are flanked by plains, less so on the west and southwest where they are bounded by high plateaus. The Rocky Mountains comprise more than 100 individually named ranges that form a belt extending for slightly more than 5,000 km, from near Santa Fe, New Mexico, on the south to the Bering Sea on the north (Fig. 1). The belt varies in width from less than 100 km in the Canadian Rockies to nearly 600 km in the Middle Rockies of Wyoming and northeast Utah. The summits of the ranges rise 1,500 to 2,100 m above adjacent lowlands, to heights 1,800 to 4,400 m above sea level. The Southern Rockies of Colorado have the greatest amount of area, between 3,300 and 4,400 m, and the highest peak, Mount Elbert (4,400 m). The largest area of low mountains is in the Northern Rockies of Idaho and Montana, where summits are commonly only 2,100 to 2,400 m above sea level.
A substantial part of the Rocky Mountain region consists of lowlands, in the form of basins and fault-bounded troughs and trenches that lie between ranges. The Rocky Mountain Trench is perhaps the most spectacular fault-bounded lowland, even if it is not the most representative. It extends north from Flathead Lake, Montana, more than 1,500 km, and forms
Colorado Plateau
Authors: Graf William L. , Hereford Richard , Laity Julie , Young Richard A. 
Published: April 2015

Abstract
Field studies in the Colorado Plateau occupy an honored place in the development of geomorphic theory. The purpose of this chapter is to briefly review the foundational, regional, and process-oriented studies in the region, and to provide a review of promising threads of inquiry set in a context of more than a century of geomorphologic research in the region.
The Colorado Plateau has sharply defined boundaries that separate it from neighboring geomorphic provinces (Fig. 1; for details see Thornbury, 1965). On the west, faults and the perimeters of volcanic plateaus mark the boundary between the Colorado Plateau and the Basin and Range Province. The boundary extends across the southern edge of the plateau where it is less radically defined, but is nonetheless visible on the surface in the form of an uplifted edge of sedimentary rocks known as the Mogollon Rim, which extends from northwest Arizona diagonally into north-central New Mexico. The eastern and northern boundaries are delineated by the contact between sedimentary rocks and upthrust or folded crystalline rocks of the Rocky Mountains.
The plateau is a definable tectonic unit relatively easily separated from other provinces, but it shows considerable internal variation (Fig. 1; for details see Hunt, 1974a). The interior of the kidney-shaped Colorado Plateau Province reveals a series of subsections that depend on geologic and geomorphologic definition. The centrally located Canyon Lands Section is dominated by gently folded sedimentary rocks, while the western High Plateaus Section reveals widespread accumulations of volcanic materials.
The Uinta
Central America and the Caribbean
Authors: Gardner Thomas W. , Back William , Bullard Thomas F. , Hare Paul W. , Kesel Richard H. , Lowe Donald R. , Menges Chris M. , Mora Sergio C. , Pazzaglia Frank J. , Sasowsky Ira D. , Troester Joseph W. , Wells Stephen G. 
Published: April 2015

Abstract
Central America and the Caribbean islands encompass an extraordinarily diverse suite of geomorphic processes and land-forms created by the interaction of distinctly different climatic, tectonic, and lithologie domains. The purpose of this overview is to review some of the significant types of geomorphic contributions from the region; to provide a summary of the climatic and tectonic setting of the region; and to introduce the four sections that comprise this chapter.
Climatic extremes within the region are significant for their impact on process and form diversity. For example, during the Pleistocene a climate gradient created by topographic relief produced glacial deposits in the Cordillera de Talamanca, Costa Rica (Hastenrath, 1973), that are only several kilometers from economic laterite and bauxite oxisols in the adjoining Valle de El General (Castillo and others, 1970). Modern climatic zones range from wet tropical with annual rainfall in excess of 4.0 m in parts of Costa Rica, Guatemala, and Panama to dry tropical steppe with annual rainfall not exceeding 1.0 m in parts of Nicaragua, Honduras, and the Caribbean. Some of these climatic zones at lower elevations that did not experience the dramatic Pleistocene climatic oscillations of North America provide superb locations for the study of climate, process, and form without the overprint of relict climatic landforms.
Superimposed on the climatic diversity is an active plate setting that juxtaposes areas of rapid crustal movement and complex geology with relatively more stable carbonate platforms, for example, in the area of the Yucatan and Motagua fault zone. This
Columbia and Snake River Plains
Authors: Baker Victor R. , Greeley Ronald , Komar Paul D. , Swanson Donald A. , Waitt Richard B. 
Published: April 2015

Abstract
This chapter treats two areas of the northwestern United States characterized by great late Cenozoic outpourings of basaltic lava. The western part of this region is underlain by flood basalt of the Columbia River Basalt Group. As discussed below by Waitt and Swanson, this area constitutes the Columbia Plain. The laterally extensive, thick cooling units of the Columbia River Basalt Group contrast with the thinner, less extensive flows of the Snake River Plain, which lies to the southeast. Lavas of the Snake River Plain were emplaced coincident with Pliocene-Quaternary rifting, from about 5 Ma to present.
Much of the Columbia Plain is overlain by tens of meters of Pleistocene loess, which is extensively dissected to form the rolling topography of the Palouse Hills. In the northeast, broad channels were carved into the Palouse loess and underlying basalt by cataclysmic Pleistocene floods. The characteristic flood erosion of the basalt impressed early settlers as a scaring of the earth by removing its protective soil, and the term “scabland” was applied to it.
The best known geomorphic studies in the Columbia Plateau centered on the role of cataclysmic flooding in the origin of its landscape. The central figure in this research for over half a century was J Harlen Bretz (Fig. 1), a glacial geologist at the University of Chicago. Bretz (1923a) used the name “Channeled Scabland” to describe the area of loess-mantled northeastern Columbia Plain that was scoured by flood channels. In 20 major articles and monographs, mostly published between
The Interior Mountains and Plateaus
Authors: Bovis Michael J. 
Published: April 2015

Abstract
This chapter evaluates the most significant contributions to geomorphology from a region of considerable climatic, topographic, and geologic diversity (Fig. 1). Climate ranges from subtropical semidesert, through temperate montane and alpine environments, to boreal forest and arctic tundra. This wide range of conditions has prompted the appearance of significant publications in virtually every subdiscipline of geomorphology. The region is renowned for original contributions in topics as diverse as erosional surfaces, volcanic landforms, glaciation, periglacial landforms, and fluvial and hillslope processes. These form the major themes of this chapter. There are two criteria for the inclusion of a work in this review. The first, and most restrictive, is that it contain a fundamental contribution to geomorphic theory not previously stated elsewhere. If this were followed rigorously, relatively few works would be included. A second criterion is that the work be a significant contribution to the geomorphology of the region. Although this chapter is not an account of regional geomorphology, the second criterion has been adopted for the following reasons. First, it allows contributions to basic theory to be included. Second, it places great value on regional or local studies that have contributed to knowledge of the morphology, the evolution, and the geographic distribution of particular landforms. Since complexity of landform evolution and distribution is the rule, deeper theoretical understanding of landforms in this region, as elsewhere, has occurred only after a prolonged period of empirical investigation.
In this chapter, relatively little attention is paid to Quaternary paleoenvironments and topics
Appalachian mountains and plateaus
Authors: Mills Hugh H. , Brakenridge G. Robert , Jacobson Robert B. , Newell Wayne L. , Pavich Milan J. , Pomeroy John S. 
Published: April 2015

Abstract
William Morris Davis (1888) considered the Appalachians to have had an important role in the development of geomorphology. He saw the systematic study of topography as largely of American origin, and suggested that there were two steps in its development. The first began about 1840 with the founding of the Eastern state surveys, during which geologists such as Lesley (1856) established the intimate relationship between topography and structure (in the broad sense) in the Appalachians. During this first step, according to Davis, topographic form was regarded as acompleted product of extinct processes. Topography revealed structure, but it did not then reveal the long history that the structure has passed through. … The systematic relation of forms to structure, base level, and time; the change of drainage areas by contest of headwaters at divides; the revival of exhausted rivers by massive elevations of their drainage areas; all these consequences of slow adjustments were then unperceived (Davis, 1888, p. 14).
The awareness of such principles, the second step in the advancement of the study of topography, came about largely as a result of the geological exploration of the western U.S., exemplified by the work of Powell (1875, 1876) and Gilbert (1877). Once this awareness came about, however, these principles were applied to the Appalachians; Davis (1888, p. 15) stressed the importance of the Appalachians in this second phase as well as the first: If it be true that the greater part of this second advance is American like the