bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Quaternary alluvial stratigraphy and early Holocene archaeology of Whitewater Draw, Arizona
Authors: Waters Michael R.
Published: April 2015

In 1926, Byron Cummings discovered artifacts associated with the remains of mammoth (Mammuthus), horse (Equus), camel (Camelops), and bison (Bison) in Whitewater Draw, an arroyo near the town of Double Adobe in the semiarid Sulphur Springs Valley, Arizona (Figs. 1 and 2). Unlike the Folsom projectile points discovered with the bones of extinct bison that same year, these artifacts were milling stones and handstones, not projectile points. Sayles and Antevs (1941) later assigned the early artifacts from Double Adobe and from several other localities in Whitewater Draw to the Sulphur Spring stage of the Cochise Culture. They believed that the Sulphur Spring stage artifacts occurred in primary association with extinct megafaunal remains and that the Sulphur Spring stage dated between 12,500 and 11,000 B.P.

Since the investigations of Sayles and Antevs, many questions arose concerning the Sulphur Spring stage as the archaeological data base for the American Southwest expanded, especially with the recognition of the Clovis Culture and the establishment of a timetable of late Pleistocene extinctions. Some researchers (Martin and Plog, 1973; Haury, 1983) suggested that the sites of the Sulphur Spring stage may be specialized plantprocessing stations of the Clovis Culture, based on the apparent age of the Sulphur Spring stage artifacts and their association with extinct megafauna. However, other researchers (Willey and Phillips, 1958; Whalen, 1971; Irwin-Williams, 1979) questioned the temporal association of extinct fauna with artifacts of the Sulphur Spring stage and suggested that the artifacts belong to the Early Archaic period and postdate the Clovis
Geologic contexts of archaeological sites in Beringia
Authors: Thorson Robert M.
Published: April 2015

From reviews of Beringian archaeology (for example, West, 1981, 1983; Morlan, 1986; Dumond, 1980; Dixon, 1985) we know that thousands of sites occur in diverse geologic settings throughout the region (Fig. 1). Examples include artifact horizons within tephra layers in the Aleutian Islands, cave detritus from Yukon Territory, muck deposits in Siberia, abandoned beach ridges along the Bering Sea, between reported glacial tills in southeast Alaska, and in eolian and fluvial sediments of the Alaskan interior. Sites of all ages are most frequently located in river valleys and mountain passes, along stable coastlines, and in quarry and overlook settings, locales comparable to those documented in the ethnographic literature (VanStone, 1974). The chronologic range of sites, however, remains controversial.

Proponents of an early human presence (for example, Morlan, 1986; Bonnichsen and others, 1987) rely on patterned modifications of bones from extinct fauna and more recently on the presence of microflakes in securely dated pre-late Wisconsinan contexts. Proponents of a terminal Pleistocene entry (for example, Haynes, 1982; West, 1983) rely on a variety of sites for which the oldest radiocarbon dates associated with diagnostic artifacts range from about 11.5 to 10.5 ka. Chronologic patterns of site distribution during the Holocene are even more enigmatic. Did an existing human population become locally extinct during full-glacial times (Schweger and others, 1982; Hamilton, 1978)? To what extent did the early Holocene reforestation (Barnosky and others, 1987) and insolation-driven climatic changes (Heusser and others, 1985) affect site distribution in space and time (Aigner, 1986)? Were sea-level
Caves and tunnels at Teotihuacan, Mexico; A geological phenomenon of archaeological interest
Authors: Barba P. L. A. , Manzanilla Linda , Chávez R. , Flores Luis , Arzate A. J.
Published: April 2015

In Prehispanic Mexico, natural cavities (tunnels, caves, rock shelters) were closely linked to religion and mythology. There are several myths that tell about the creation of the sun and the moon, saying they came forth from caves. In other myths, either the human race or a given group or groups (for example, the seven tribes of Chicomoztoc) emerged from the center of the Earth; it was even said that food itself was obtained from the underworld, when the god Quetzalcoatl stole maize from the ants (Heyden, 1981). For Prehispanic people, the cave meant the entrance to the underworld (and, thus, a funerary chamber), but it also meant the access to the Earth's womb or the mouth of the terrestrial monster. Consequently, it was the ideal place for fertility to be stimulated. This is why in some places in ancient Mexico, the ceremonies where people prayed for water for the harvests were held in caves, which were, together with hill summits and springs, the dwelling places of the water spirits (Heyden, 1981).

Besides its ideological function, the cave was a dwelling option since prehistoric times. In Mexico, some examples of such caves are found in excavations in the valleys of Tehuacan, Valsequillo, Oaxaca, Tamaulipas, and the Chiapas Central Depression, among others. In the Codex Xolotl, the Chichimeca chiefs, Xolotl and Nopaltzin, are portrayed in the cave surroundings, evidence that these groups probably inhabited caves for many years. People living in caves are also pictured in the Relaciones de Michoacán manuscript; they
Archaeological sites on the North American continental shelf
Authors: Stright Melanie J.
Published: April 2015

The oral history of the Alsea Indians in Oregon describes the use of a large peninsula for hunting and gathering on the coast "a long time ago." The Chumash Indians of southern California have a myth that describes "offshore houses" in the Santa Barbara area. In New England, some of the inland tribes, when questioned by the early settlers concerning their origin, replied that they were descended from inhabitants of the sea coast. Although long-held oral traditions among the American Indians allude to man's use of the now-submerged continental shelf, only within the last 20 years have we seriously considered the possibility of prehistoric archaeological sites on the continental shelf. In 1966, the first well-recognized treatise on continental shelf archaeology appeared (Emery and Edwards, 1966), although several researchers recognized the archaeological potential of the continental shelf much earlier. The methods and technology to actively search for and evaluate these sites have been employed only within the last decade.

Archaeological sites are inundated as a result of glacioeustatic and glacio-isostatic adjustments, and local tectonics (for example, faulting and subduction). During the Holocene, eustatic sea-level rise and subsidence of coastal areas caused inundation of the basal portions of many Late Archaic coastal sites. Many older sites are now completely inundated as a result of eustatic and isostatic adjustments following the late Wisconsinan glacial epoch. While some sites appear to be completely in situ, other sites consist of only redeposited material. The original geologic context of inundated archaeological sites discovered through dredging activities
Mollusks and coastal archaeology; A review
Authors: Rollins Harold B. , Sandweiss Daniel H. , Rollins Judith C.
Published: April 2015

During the last 20 years, mollusks were elevated to a rather elite position in the dating, interpretation, and reconstruction of environments and activities at coastal archaeological sites. Previously viewed as rather passive constituents of such sites, mollusk shells now are used for their stable-isotope and traceelement content in paleotemperature and paleosalinity analyses, for 14C and amino-acid content in the dating of archaeological occurrences, as "tape recorders" of environmental perturbations and seasonal and climatic changes, and as indicators of past human behavior.

In this review we have attempted to capture the flavor of this activity as well as predict future directions. We recognize that our treatment of the subject is not exhaustive, but hope that we have stressed the more dynamic aspects of mollusks in coastal archaeology.
Pedology in archaeology
Authors: Holliday Vance T.
Published: April 2015

Most archaeologists recognize that a relationship exists between the cultural remains they find in the ground and the soils. Beyond that simple relationship, however, archaeologists' understanding of what can be learned from soils and indeed what a soil is and is not varies tremendously. In general, the applications of soil studies in archaeology are either very large scale, such as the capability of regional soils to support agriculture or use of soils as stratigraphic markers, or very small scale, for example, studying the particle-size distribution or chemistry of a soil. There is a significant middle ground in soil studies that is often overlooked. This involves investigation of soils as three-dimensional bodies intimately related to the landscape, focusing on their classification and genesis. This study of soils and their natural setting is a part of soil science called "pedology." The aspect of pedology most directly related to archaeology evolves from Quaternary geology and geomorphology (rather than agriculture) and sometimes is referred to as soil-geomorphology (e.g., Ruhe, 1983; Birkeland, 1984; Catt, 1986). This chapter will review basic aspects of pedology, and how they apply to archaeology in North America.

There is considerable literature concerning the use of soils in archaeological investigations. Much of the initial, substantive work was done in Great Britain (e.g., Cornwall, 1958, 1960), establishing a tradition that continues (e.g., Limbrey, 1975; Shackley, 1981). In North American archaeology, soils were originally used primarily as stratigraphic markers and continue to be so used with considerable success (e.g., Judson, 1953; Haynes, 1968,
The soil-evolution model as a framework for evaluating pedoturbation in archaeological site formation
Authors: Johnson Donald L. , Watson-Stegner Donna
Published: April 2015

Soil and near-surface material affected by pedogenesis is the principal medium in which field archaeologists dig. Soil encases the cultural resources from which prehistoric human behavior is inferred. In fact, the various soil properties, factors, and conditions often determine the extent to which perishable materials are preserved, modified, moved, or destroyed by post-burial processes. The soil is not, however, the same material that was originally present when the artifacts were deposited. The dynamic nature of the soil system is such that changes in its morphology, thickness, and biophysicochemistry occur over time, and the sum of the changes is different from one site to another. Changes may include evolution of new properties, features, and horizons, such as illuvial cutans of clay, humus, iron and manganese, argillic horizons, and concretions, among others. Such endogenous or intrinsically evolved properties and features are termed "pedogenic accessions." Once formed, such accessions may persist, undergo further change, or be obliterated, as when clay cutans are broken up in Bt horizons via shrink-swell action, or when carbonate nodules dissolve following an increase in soil acidity.

Further, some accessions may cause feedback processes that redirect pedogenic pathways in progressive or regressive directions. For example, certain subsoil horizons may gradually increase in density until threshold development is reached (fragipans, clay pans) after which they become barriers to downward water percolation and function as aquitards or aquicludes. Feedbacks such as perched water tables and attendant profile gleying, mottling, and cessation of profile deepening may be triggered. Then there are the
Chert petrography and its potential as an analytical tool in archaeology
Authors: Prothero Donald R. , Lavin Lucianne
Published: April 2015

Archaeologists use various properties of stone (lithic) artifacts to determine their sources, which can suggest trade or procurement patterns for the artifacts at a particular site. Sometimes source identification is relatively straightforward, because the ways in which certain artifacts were manufactured are often diagnostic of a particular place and time. In addition to the manmade properties of artifacts, the natural physical properties are often distinctive as well. In the past, chert artifacts were assigned a source based on macroscopic features such as color, luster, inclusions, and texture. Yet these features are not always diagnostic of a single source, and are difficult to assess objectively (Lavin, 1983a; Lavin and Prothero, 1987; Luedtke, 1976). For example, yellow, brown, and red cherts in New Jersey are usually attributed to the "Pennsylvania Jasper," yet the color is deceptive. Many cherts attributed to this source are in fact from other sources, and others from the "Pennsylvania Jasper" source are not yellow, brown, or red (Lavin and Prothero, 1981, 1987).

There are several techniques that can be used for a more refined analysis of chert artifacts. One, neutron activation analysis, has been used successfully by a number of workers (Aspinall and Feather, 1972; De Bruin and others, 1972; Ives, 1974, 1975; Luedtke, 1976, 1978, 1979; Miller, 1982; Sieveking and others, 1972; Spielbauer, 1976). Other geochemical techniques require far more equipment and expertise than are available to most archaeologists. However, pétrographie, or thin-section, analysis is a simple, inexpensive technique that has been standard in geology for over
Applications of high-resolution geophysical methods to archaeology
Authors: Wynn Jeffrey C.
Published: April 2015

A quiet but accelerating revolution has taken place in archaeology over the last several decades. Classical archaeological methods, including trenching with trowels and brushes, require an enormous expenditure of human energy. Individuals carrying out this work are often students or local day laborers, working under the supervision of trained professional archaeologists who direct the work around surface manifestations—if any—of ancient human cultural activity. Modern mineral exploration technology, principally of a geophysical character, is now being increasingly incorporated in archaeology to increase the effectiveness of field work.

Despite the proven potential for vastly increasing efficiency, most archaeologists are yet unable to utilize geophysical methods in their work. The main reason is probably that geophysical equipment and contractors are relatively expensive and (with a few notable exceptions such as U.S. Army Corps of Engineers projects) archaeology traditionally is a poorly funded profession. Funding for the work usually comes from small grants from academic institutions or from philanthropic contributions, and much of the work is still done on a volunteer or even a pay-forthe- privilege-of-working basis.

A second reason for limited use of advanced technology is time. In the past, several large projects, such as the Tombigbee Waterway, Dolores Reservoir, and Black Mesa coal mining projects in the United States, have involved significant funding by the federal government (John Weymouth, oral communication, 1985). Often, despite large sources of funding, very little, if any, geophysical work (or even trenching) is done because the effort usually is constrained by a pressing need for a land-use decision.
Archaeological geology in western Canada; Techniques, approaches, and integrative theme
Authors: Wilson Michael Clayton
Published: April 2015

Integration of geology and physical geography with archaeology in Canada dates from before 1900, and was summarized in part by Noble (1972). Early geological surveys were conducted by scientists of the Geological and Natural History Survey of Canada who collected information not only about geology, but also about native place names, archaeological sites, and a host of natural history topics (for example, Dawson, 1885; Tyrrell, 1887). Subsequently, geologists Ernst Antevs and W. A. Johnston became involved in research and speculation concerning the early peopling of North America through the “ice-free corridor” between Laurentide and Cordilleran ice masses.

Not surprisingly, then, interdisciplinary studies involving the earth sciences and archaeology were traditionally viewed as important elements included in university archaeology curricula in Canada. The cooperation embodied in archaeological geology was already established, as it was in many other areas of the world, by the 1960s. Examples from that period of geological studies at archaeological sites in the Arctic and Subarctic include Mackay and others (1961) and MacNeish (1964). MacNeish was a strong advocate of interdisciplinary archaeological studies during his tenure at the University of Calgary in the mid-1960s. In Saskatchewan, geological and pedological studies were integral parts of early projects by the Saskatchewan Museum of Natural History (Wettlaufer, 1956; Wettlaufer and Mayer-Oakes, 1960). If anything, these excellent studies more strongly exemplified the archaeological geology ideal than many that followed. Early work in Manitoba by Johnston (1946) underscored the significance of glacial Lake Agassiz in the late Pleistocene and early Holocene history of
North American continent-ocean transitions over Phanerozoic time
Authors: Speed Robert C.
Published: April 2015

This chapter presents a synthesis of the structure and Phanerozoic tectonic evolution of continent-ocean transitions around nearly the entire North American continent. Its objectives are to compare and contrast the modern transitions and Phanerozoic histories of specific margins of North America discussed in other chapters of this book and in the Transect displays (see Foreword) and to present ideas on processes in the evolution of continent-ocean transitions.

A word about the focus on the continent’s margins and their place in the global scheme of tectonics may be warranted. The modern transitions between the North American continent and adjoining oceanic basins are where plate tectonics has most recently affected the continent aside from rigid translation. At active margins, where oceanic lithosphere underrides or slides along the continent, the development of the margin is ongoing and may have been continuous over a long time. In contrast, at passive margins where the continent has split and sea-floor spreading has occurred, the continent-ocean transition was developed in a discrete event and was discontinuous in time. At passive margins, the most recent North American transitions range from Holocene to mid-Mesozoic. At collisional margins, where the North American continent is or was on the underriding plate, the development of the margin was also discrete and discontinuous. As with passive margins, an existing collisional margin is generally the product of an ancient event.

During the development of all margin types, the motions between the North American plate and adjacent plates have commonly been broadly distributed and nonuniform
Continental margin of the eastern United States
Authors: Rankin Douglas W.
Published: April 2015

The continental margin of eastern North America has been studied as part of the North American Continent-Ocean Transect Program by synthesizing existing data along six corridors, each at least 100 km wide, between Newfoundland and Georgia that extend from the Phanerozoic craton to the oceanic crust. The term Phanerozoic craton is used here for a cratonal area that has not undergone significant deformation since the beginning of Phanerozoic time. One of these corridors is in Canada (Dl; Haworth and others, 1985), and two additional Canadian transects (D2 and D3; Keen and Haworth, 1985a, 1985b) cross the present continental margin, but do not extend westward to the craton. Herein I analyze the evolution of the eastern continental margin as depicted by the five corridors or transects, El through E5, prepared or in preparation for the United States. The five transects in eastern United States are outlined in Figure 1 and are as follows.

E1, Adirondacks to Georges Bank (Thompson and others, 1993). The corridor length is 1000 km.

E2, New York Appalachian basin to the Baltimore Canyon trough (Drake and others, unpublished). The corridor length is 860 km.

E3, Pittsburgh to Baltimore Canyon trough (Glover, 1989; Glover and others, unpublished). The corridor length is approximately 850 km.

E4, Central Kentucky to the Carolina trough (Rankin and others, 1991). The corridor length is 1100 km.

E5, Cumberland Plateau to Blake Plateau (Hatcher and others, 1994). The corridor length is approximately 1280 km. Because of the time constraints, E2 and E3 will not
Crustal structure and evolution of the southeastern margin of North America and the Gulf of Mexico basin
Authors: Buffler Richard T. , Thomas William A.
Published: April 2015

The Gulf of Mexico basin on the southeastern margin of North America is one of the most extensively studied basins in the world. Most of this work, however, has been concentrated on the shallower parts of the thick sedimentary section around the periphery of the basin, primarily related to the search for oil and gas and other minerals. Although comparatively little is known about the details of the more deeply buried parts of the sedimentary section and the crust below, enough geological and geophysical data exist now to enable compilation of a reasonable framework for the entire basin and document the evolution of the crust in general terms. The crust in the region contains the record of three successive phases of plate motion:

1. Divergent motion. Late Precambrian to early Paleozoic rifted margin and early Paleozoic south-facing passive margin along the southeastern edge of the North American craton.

2. Convergent motion. Late Paleozoic diachronous Appalachian-Ouachita orogenic belt, including foreland thrust belts, interior belts, and accreted terranes.

3. Divergent motion. Early to middle Mesozoic rifted margin and middle Mesozoic to present passive margin centered around a small ocean basin (present Gulf of Mexico basin).

Mesozoic rifting introduced a new set of extensional faults, including a northeast-trending rift set and a northwest-trending transform set. Some faults used planes of weakness related to late Paleozoic compressional structures, and the Mesozoic transform system essentially duplicated an early Paleozoic transform system. Mesozoic extension resulted in a broad area of stretched or attenuated continental crust (transitional
Phanerozoic tectonic evolution of Mexico
Authors: Ortega-Gutiérrez Fernando , Sedlock Richard L. , Speed Robert C.
Published: April 2015

We present a tectonic evolution of Mexico over the past 600 m.y., with focus on the position of southern margin of Proterozoic North America in Mexico, the Phanerozoic events that shaped this margin, and the accretion of terranes that built Mexico out from that margin to its present configuration.

The evolution of Mexico is a peculiar and difficult problem in tectonics. Whereas the kinematic history of the region of Mexico, for example, the end of Proterozoic continental breakup, the collision of North and South America in the late Paleozoic, the drifting apart of those two continents in the Mesozoic, and the motions of plates in the Pacific basin relative to North America in Cretaceous and Cenozoic time, is reasonably well known, the kinematics of terranes now in the region is poorly understood. In large part, this disparity is due to the extraordinary extent and volume of Cenozoic volcanism. Although such volcanism informs us about Cenozoic convergence, it cautions that the crust of Mexico has probably undergone major modification in Cenozoic time. Moreover, the volcanic cover limits greatly the direct access to older rocks and structures necessary to develop the story of an evolution that is well resolved in space and time. A tectonic synthesis of Mexico thus requires more assumptions than for most mountainous regions.

Our model of tectonic evolution of Mexico attempts to satisfy both far-field and sparse near-field kinematic histories and existing geologic and geophysical data. This chapter is a companion to an in-depth synthesis of data, identification
Synopsis of geologic history portrayed along Corridor C-3
Authors: Howell D. G. , Vedder J. G.
Published: April 2015

Corridor C-3 (Fig. 1) traverses the transition from oceanic crust to cratonal rocks of North America along a 1,500-km transect from offshore southern California to central New Mexico (Howell and others, 1985; Gibson and others, 1985). The western end of the transect is offshore in an oceanic seamount province of the Pacific plate. Eastward, it crosses the southern California borderland and emerges onshore in the batholith-dominated Peninsular Ranges. C-3 spans the Salton trough, a transform rift floored by nascent oceanic crust, and the Basin and Range structural province, formed by extension and disruption of cratonal rocks. The eastern end of C-3 is on the stable craton.

Neogene tectonism has severely disrupted the older structural grain between the oceanic lithosphere and the craton. Much of this young tectonism is attributed to interactions along the plate edges after the spreading ridge system separating the Pacific and Farallon plates inpinged upon the North American plate in late Oligocene time. Two triple junctions—one migrating northward, the other southward relative to the Pacific plate—formed as the spreading system moved eastward relative to the North American plate. The San Andreas fault system began to develop within a broad zone of right shear as the triple junctions moved apart. The main strand of the San Andreas is but one of many northwest-trending right-lateral faults in the system. The boundary between the Pacific and North American plates is best perceived as a broad zone of right shear rather than a specific fault trace.

The continental crust of the
Modern active oceanic margins of North America
Authors: Huene Roland von , Riddihough Robin
Published: April 2015

Modern convergent and strike-slip margins are crossed by six continent/ocean transects (Fig. 1). Along these margins, continental and oceanic crust are separated by a seismically active tectonic contact, which is the boundary between the North American Plate and the Pacific or Cocos Plates. Four transects cross convergent margins where oceanic crust underthrusts continental crust (A-2, B-2, B-3, and H-2). One transect (B-l) is across the Queen Charlotte Transform Fault, a part of the Pacific-North American plate boundary, which is as long as the better-known San Andreas Fault. Another transect (A-3) crosses a collision zone and the controversial transition fault zone, which is interpreted by some as a highly oblique thrust and by others as inactive during the past 5 m.y. or more, and only recently an active fault.

We summarize here the tectonic interpretations of these boundaries made by the transect teams, and results from work completed after the transects were assembled. After transect compilation, the multichannel seismic records across active margins in A-2 and H-2 were reprocessed, and a new record was acquired in the B-2 transect area.
Professional practice and societal organizations
Authors: McClure Cole R. , Sorrough Gail L. , Gray Richard E. , Galster Richard W. , Varnes David J. , Kiersch George A.
Published: April 2015

Today, engineering geologists in private industry occupy key positions in the planning, design, and construction of many different kinds of engineering works. Since the beginning of this century, it typically has been the practice of engineering-construction companies to rely on outside consultants for projects requiring geological expertise. However, with the end of World War II and the rapid development of the early 1950s, engineering-construction companies in North America began to hire geologists as staff members.

A recent survey of the older major engineering-construction companies by Bechtel (1986) established that about half of the firms support engineering geology staffs in-house, while half rely solely on consultants, either individuals or specialty groups. Furthermore, many of the companies that retain engineering geologists in-house occasionally supplement their staff input with the services of outside consultants for a variety of reasons, including fulfilling contractual obligations, enhancing the work capabilities in a specific geographic area, or reinforcing expert opinions in controversial situations.

Today, some of the major engineering-construction companies that support their own in-house geoscience experts include Bechtel Civil, Inc.; EBASCO Services, Inc.; Fluor Engineers, Inc.; Harza Engineering Company; Morrison-Knudsen Engineering Company; United Engineers and Constructors; and Stone and Webster Engineering Corporation.

Bechtel was one of the first engineering companies to hire staff geologists. In the early 1950s, they hired Ben Warner, Victor L. Wright, Robert J. Farina, and Charles P. Benziger to work on a project-by-product basis. However, lack of permanent job status and associated benefits, as well as the inability in those days to advance professionally within the company ranks, was not encouraging to the geologists or beneficial to the company, and consequently, many of these geologists moved on to other professional situations.
Rebound, relaxation, and uplift
Authors: Nichols Thomas C. , Collins Donley S.
Published: April 2015

Rebound is defined as the expansive recovery of surficial crustal material, either instantaneous, or time dependent, or both, and is initiated by the removal or relaxation of superincumbent loads (Nichols, 1980). The displacements caused by rebound allow elastic and inelastic relaxation of the crustal masses to occur. The outward and upward movements associated with rebound are uplift displacements related to rebound processes. Rebound of geological materials is attributed to stress relief, but the process is poorly understood and the basis for predicting time-dependent rebound has not been clearly established. Not only are changes of stress important to the rebound process, but so are fabric, material properties, and anisotropy of the geologic materials, as well as external environmental factors such as moisture and temperature (Nichols, 1980). The problem of rebound is one with which design and construction engineers must deal, whenever the equilibrium of geologic materials is disturbed, especially in large excavations both surface and underground. In areas where rebound deformations can significantly affect engineering structures, it is desirable to understand rebound behavior, and to determine practical guidelines for prediction of the short- and long-term consequences of rebound.

The phenomenon of rebound undoubtedly has been observed by ancient as well as modern quarry operators, civil engineers, and applied geologists. In the United States and England, recorded accounts of rebound and actual measurements made to study the phenomenon appear in the mid-19th century (Nichols and Varnes, 1984) describing spontaneous and explosive expansion in a wide range of quarried rock types (sandstones, granites, vein rock).
Investigations of existing engineered works
Authors: Fisher Paul R.
Published: April 2015

Investigations in conjunction with operating engineering works and structures are receiving increasing emphasis throughout North America. The most obvious reason for the investigations is observed distress of the works, while less obvious but common causes are decaying infrastructure, advances in state-of-the-art engineering, and increased regulatory activity due to safety concerns. These latter causes frequently lead to modification of the original design.

In the early 1980s, the need for maintenance and rehabilitation of the nation’s engineering-works infrastructure was recognized and widely published as a national problem of great magnitude. Phrases such as “decaying infrastructure” and “crumbling public facilities” were used by the engineering and construction industry publications or by the general news media. The Public Works Improvement Act (Public Law 98-501) constituted a significant step in formulating a national response to the long-term intrastructure needs of our modern society (ENR, 1985; Pender, 1985).

The relative cost of continuing operations, maintenance, and rehabilitation versus the investment in new construction is increasing. One indicator of the shift is seen in the civil works budget of the U.S. Army Corps of Engineers. In fiscal year 1967, construction and operations and maintenance accounted for 79 percent and 16 percent, respectively, of their budget. In fiscal year 1983, construction accounted for 42 percent and operations and maintenance for 40 percent. In fiscal year 1986, the construction budget was $0.8 billion, and the operations and maintenance budget was $1.4 billion!

Advances in state-of-the-art engineering have produced improvements in design criteria in such areas as earthquake engineering, maximum hydrologic events, strength and deformation properties of soil and rock materials, and methods of analyzing the response of structures to forces acting upon them.
The Lake Superior region and Trans-Hudson orogen
Authors: Anderson J. L. , Bauer R. L. , Chandler V. W. , Hanson G. N. , Kalliokoski J. , Morey G. B. , Mudrey M. G. , Ojakangas R. W. , Peterman Z. E. , Schulz K. J. , Shirey S. B. , Smith E. I. , Southwick D. L. , Schmus W. R. Van , Weiblen P. W.
Published: April 2015

Precambrian rocks in the Lake Superior region underlie all or parts of Minnesota, Wisconsin, and Michigan, an area along the southern margin of the Superior province of the Canadian Shield (Fig. 1). Except on the north, adjacent to Canada, the Precambrian rocks are overlapped by sedimentary strata of Paleozoic and Mesozoic age, which constitute a thin platform cover of relatively undisturbed rocks that thicken to the west, south, and east. Inliers of Precambrian rocks are exposed locally in southern Minnesota and Wisconsin, mainly in the flat valleys of major rivers, where erosion has cut below the Phanerozoic strata. The present landscape is subdued, and is inherited largely from Pleistocene continental glaciations, which produced a variety of erosional and depositional landforms. The glacier ice scoured the bedrock in the northern parts of the region, in much the same way as throughout most of Canada, and deposited materials of diverse lithology and provenance, as much as 200 m thick, over much of the remainder of the region. The Precambrian rocks in the region record an extended interval of crustal development and evolution that spans nearly 3 b.y. of earth history. This interval of geologic time is not continuously recorded in layered and intrusive units, but instead is punctuated by specific rock-forming and tectonic events that can be deduced from geologic relations and placed in a chronometric framework by isotopic dating. (Fig. 2, also see correlation chart for Precambrian rocks of the Lake Superior region, Morey and Van Schmus, 1986; and Bergstrom and Morey, 1985.)
The Wyoming province
Authors: Erslev E. A. , Frost C. D. , Karlstrom K. E. , Page N. J. , Zientek M. L. , Reed John C. , Snyder G. L. , Worl R. G. , Bryant Bruce , Reynolds M. W. , Peterman Z. E.
Published: April 2015

The Wyoming province is the region in Wyoming and adjacent states underlain by rocks of Archean age (Plate 2). It is an Archean craton bordered on the east and south by younger Precambrian provinces (Plate 1). Precambrian rocks are only exposed in the cores of the Laramide (Late Cretaceous to Early Tertiary) uplifts, and outcrops constitute less than 10 percent of the area underlain by Archean basement. Between uplifts, basement rocks are covered by thick Phanerozoic strata, so that extrapolations of geology from uplift to uplift are generally tenuous. Reconstructing the Archean history of the Wyoming province is further complicated by deformation associated with the late Mesozoic fold and thrust belt along the western margin. Although the Archean record is fragmentary, the basement uplifts generally afford excellent exposure.

The northern and northwestern margins of the Wyoming province are poorly constrained. Archean rocks are known as far north as the Little Rocky Mountains of Montana (Peterman, 1981). According to King (1976), Archean and Early Proterozoic dates are intermingled at the northwest margin of the province in a wide zone that exhibits a gradational change from Archean dates in central Montana to Early Proterozoic dates to the northwest, reflecting increasing influence of post-Archean thermal events.

The southwestern and southern margins of the Wyoming province are also poorly constrained. Archean rocks have been reported from several ranges in the Cordilleran orogenic belt, such as the Albion and Raft River Ranges (Armstrong and Hills, 1967) and possibly the Ruby Mountains of Nevada (A. W. Snoke, personal communication, 1986).
Transcontinental Proterozoic provinces
Authors: Anderson J. Lawford , Bender E. Erik , Anderson Raymond R. , Bauer Paul W. , Robertson James M. , Bowring Samuel A. , Condie Kent C. , Denison Rodger E. , Gilbert M. Charles , Grambling Jeffrey A. , Mawer Christopher K. , Shearer C. K. , Hinze William J. , Karlstrom Karl E. , Kisvarsanyi E. B. , Lidiak Edward G. , Reed John C. , Sims Paul K. , Tweto Odgen , Silver Leon T. , Treves Samuel B. , Williams Michael L. , Wooden Joseph L.
Published: April 2015

Research on the Precambrian basement of North America over the past two decades has shown that Archean and earliest Proterozoic evolution culminated in suturing of Archean cratonic elements and pre-1.80-Ga Proterozoic terranes to form the Canadian Shield at about 1.80 Ga (Hoffman, 1988,1989a, b). We will refer to this part of Laurentia as the Hudsonian craton (Fig. 1) because it was fused together about 1.80 to 1.85 Ga during the Trans-Hudson and Penokean orogenies (Hoffman, 1988). The Hudsonian craton, including its extensions into the United States (Chapters 2 and 3, this volume), formed the foreland against which 1.8- to 1.6-Ga continental growth occurred, forming the larger Laurentia (Hoffman, 1989a, b). Geologic and geochronologic studies over the past three decades have shown that most of the Precambrian in the United States south of the Hudsonian craton and west of the Grenville province (Chapter 5) consists of a broad northeast to east-northeast-trending zone of orogenic provinces that formed between 1.8 and 1.6 Ga. This zone, including extensions into eastern Canada, comprises or hosts most rock units of this age in North America as well as extensive suites of 1.35- to 1.50-Ga granite and rhyolite. This addition to the Hudsonian Craton is referred to in this chapter as the Transcontinental Proterozoic provinces (Fig. 1); the plural form is used to denote the composite nature of this broad region.

The Transcontinental Proterozoic provinces consist of many distinct lithotectonic entities that can be defined on the basis of regional lithology, regional structure, U-Pb ages from zircons, Sr-Nd-Pb isotopic signatures, and regional geophysical anomalies.
A Broader View
Authors: Ball Theodore T. , Lang Farmer G. , Hamilton Warren B.
Published: April 2015

The preceding chapters, which deal with myriad facets of the Precambrian geology of the conterminous United States, necessarily emphasize local descriptions and details. In this chapter we consider some broader regional and global relations. Hamilton discusses some of the difficulties with conventional views of the early evolution of the crust, and speculates that the geology of Venus, as elucidated by the new Magellan imagery, may provide a model for terrestrial Archean tectonics. Farmer and Ball describe the Nd-Sm isotopic system and discuss the applications of Nd-Sm studies to the determination of model crustal ages and delineation of major crustal provinces. Finally, we summarize the development of the southern part of Laurentia, the Late Proterozoic to early Paleozoic supercontinent that was fragmented during the Paleozoic and Mesozoic to produce the North American craton.

Geologic processes have changed greatly as the Earth has progressively lost heat, and plate-tectonic models that work well for the Phanerozoic (where my own expertise mostly lies) become progressively less applicable to successively older Precambrian assemblages. These models nevertheless can be fitted with reasonable success to Proterozoic geology, as Hoffman has been the leader in demonstrating; his 1989a paper provided excellent syntheses of the geology and tectonic significance of the Proterozoic tracts of Canada and the United States in such terms. Accretionary wedges, ophiolites, fore-arc and back-arc basins, oceanic and continental magmatic arcs, and rifted-margin sedimentary wedges are all recognizable in Proterozoic assemblages although different in important ways from modern ones.

Archean rock and tectonic assemblages are markedly less yet like modern ones. Although an increasing consensus (as, Hoffman, 1989a; until recently, I concurred) holds that Archean geologic processes also were dominated by plate tectonics, major features now appear to me inexplicable in such terms.
Ordovician and Silurian
Authors: Cecile M.P. , Norford B.S.
Published: April 2015

Most Ordovician and Silurian rocks in western and northwestern Canada were deposited on the North American craton and its western continental margin. Strata of these ages have also been recognized in three allochthonous terranes in the Cordillera, described in the companion volume on the Cordilleran Orogen (Gabrielse and Yorath, 1991).

The continental margin is equated with the Cordilleran Miogeocline of western Canada. The miogeocline/craton boundary is along a hinge line west of which the rate of thickening of Paleozoic strata increases significantly. On the basis of initial 87Sr/86Sr ratios for Mesozoic and younger plutonic rocks (Armstrong, 1979) that intrude them, all autochthonous Ordovician and Silurian strata, of both platformal and basinal facies, are inferred to be underlain by attenuated continental crust, and are thus in the miogeocline. Oceanic rocks are virtually unknown, and if present are either buried beneath younger strata, masked by metamorphism, and/or transported northwestward by Mesozoic and Cenozoic strike-slip faults. The only strata of this age that may be oceanic are rocks of the Kootenay Terrane in southernmost British Columbia.

The Cordilleran Miogeocline formed in Late Proterozoic to Early Cambrian time (see Bond and Kominz, 1984). It is considered to be a continental margin of Atlantic type that was affected by several periods of renewed extensional tectonism, one of which occurred during late Early Ordovician and Middle Ordovician time.

The eastern part of this ancient continental margin and adjacent craton were characterized by shallow-water, carbonate platforms and/or land areas composed mostly of exposed older Paleozoic and Precambrian
Devonian
Authors: Moore P. F.
Published: April 2015

The region described in this subchapter lies between the craton and the western edge of the carbonate platform built upon the Devonian continental shelf within one or two hundred kilometres of the continental margin. Sediments deposited west of the platform edge are described in the companion volume, “Geology of the Cordilleran Orogen in Canada” (Gabrielse and Yorath,1991). The depositional record described here starts with rocks deposited in Late Silurian time following a widespread regression accompanied by epeirogenic uplift, warping, and erosion. These rocks are the first of Kaskaskia sequence (Sloss, 1963). The record ends at the base of dark radioactive shales spanning the Devonian-Mississippian boundary and marking a major transgression. In the far north, this transgression is masked by a clastic wedge originating in the Ellesmerian Orogen of the Arctic Islands and northern Alaska.

Within the region, Devonian sediments cover an area of 2 500 000 km2. Thickness varies greatly from place to place. The thickest carbonate packets occur at the margin of the platform; close to Selwyn Basin, for example, the “Bear Rock sequence”, one of the five divisions of the Devonian analyzed here, alone constitutes over 2000 m of carbonate strata. In contrast, some bathymetric basins, such as the one occupying the Mackenzie Valley region during the Givetian, were starved of sediment.
Triassic
Authors: Gibson D.W.
Published: April 2015

Triassic rocks of the Interior Platform and eastern Cordillera of Canada have long been recognized as an interesting and variable sequence of marine strata occupying an elongate belt that extends from the United States border on the south to 69°N latitude and Beaufort Sea on the north (Fig. 4G.1, 4G.2). Triassic deposits are best developed in Western Canada Basin of British Columbia and Alberta, where they occupy three main physiographic provinces, Rocky Mountains on the west, Rocky Mountain Foothills, and Interior Plains to the east. Triassic rocks also occur in Liard River area of southern Yukon Territory and within northern Yukon Territory and District of Mackenzie in the British, Barn, Richardson, Selwyn, Wernecke, and northwestern Ogilvie Mountains. However, because much more published information on Triassic rocks in Western Canada Basin is available, and because of the greater development and economic importance of the system there, most of this report will be directed toward the region south of latitude 60°N.

Triassic rocks of the Rocky Mountains, Foothills, and Interior Plains comprise over 1200 m (Fig. 4G.1) of westward-thickening, siliciclastic and carbonate rocks and lesser amounts of evaporites. Contained marine faunas range in age from Griesbachian to Norian. The Triassic rocks of northern Yukon Territory display similar lithofacies but lack evaporites. The strata form a marine wedge deposited along a topographically low, tectonically stable continental shelf and shoreline, a continuation of Permian conditions at the passive western margin of the North American Craton. They form part of what is referred to as
Geomorphic Divisions
Authors: Stott D. F. , Klassen R. W.
Published: April 2015

Physiographically and geologically, western Canada consists of three great parts: a core of crystalline rocks forming the Canadian (Precambrian) Shield; a surrounding band of younger, essentially flat-lying, stratified rocks; and on the western side, a rim of highly deformed sedimentary, volcanic, and igneous rocks (Fig. 2C.1, 2C.2, 2C.3). The Canadian Shield has a slightly depressed centre, presently the site of Hudson Bay and Hudson Bay Lowland. The surrounding band of undeformed Phanerozoic rocks forms the Interior Plains on the western margin and St. Lawrence Lowland on the southern margin. These areas are characterized by lowlands, plains, and plateaux, which were substantially modified by glacial action during Pleistocene time. The outer belt of deformed rock forms the magnificent mountainous terrain of the Canadian Cordillera.

The classification of physiography in western Canada has evolved since the early writings of A.R.C. Selwyn and G.M. Dawson (1884) and a classic study by R.A. Daly (1912). The physiography of British Columbia was described by S.S. Holland (1964), and that of Canada by H.S. Bostock (1970a,b). These reports have been used extensively for the following summary. As part of the current syntheses of the Geology of Canada, W.H. Mathews (1986) has modified parts of the earlier classification of Cordilleran physiography, basing his study on landsat imagery and recent reports. The physiographic divisions set forth on Matthew’s geomorphic map are used in this section. A more detailed discussion of the geomorphology of the Cordillera may be found in the Cordilleran volume