Author: Michael David Blum
Publisher:
ISBN:
Category : Alluvium
Languages : en
Pages : 0
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The Colorado River is the trunk stream of a large polyzonal fluvial system that drains the Edwards Plateau and Gulf Coastal Plain of Texas. This dissertation summarizes previous work on the late Pleistocene and Holocene alluvial history of major valley axes in the upper Colorado drainage, on the Edwards Plateau, then presents a new spatially- and temporally-controlled allostratigraphic framework for late Pleistocene and Holocene alluvial deposits of the lower Colorado River on the Gulf Coastal Plain. The late Pleistocene and Holocene alluvial history of major streams in the upper Colorado drainage on the Edwards Plateau consists of a series of informal allostratigraphic units and bounding disconformities that were defined on the basis of areally persistent soil-geomorphic and stratigraphic relations. Chronological control for this allostratigraphic framework is afforded by numerous radiocarbon ages. Large valleys in the upper Colorado drainage contain late Pleistocene terraces and underlying fills that record an extensive period of deposition centered on the full-glacial time period, ca. 20-14,000 yrs BP. After abandonment of late Pleistocene floodplains, major streams incised bedrock valleys to present depths by ca. 11,000 yrs BP. Since that time there have been two episodes of net deposition, from ca. 11,000-5000 yrs BP, and ca. 4600-1000 yrs BP, whereas the modem incised, and in many cases underfit, channels and associated depositional environments represent the last millennium of fluvial activity. A very similar sequence of allostratigraphic units and bounding disconformities has been identified in the lower Colorado valley, on the Gulf Coastal Plain. The oldest unit of interest has been defined as the Eagle Lake Alloformation, after localities near the town of Eagle Lake that display characteristic soil-geomorphic and stratigraphic relationships with both older and younger deposits. Radiocarbon ages indicate the Eagle Lake unit was deposited during the late Pleistocene from ca. 20-14,000 yrs BP, roughly contemporaneous with full-glacial conditions. The main valley fill of the lower Colorado River has been defined as the Columbus Bend Alloformation, named after localities near the town of Columbus, and subdivided into three members on the basis of soil-geomorphic and stratigraphic relations. Radiocarbon ages indicate that Columbus Bend Member 1 was deposited during the latest Pleistocene through early to middle Holocene, from ca. 13-5000 yrs BP, whereas Member 2 represents the period ca. 5-1000 yrs BP. Columbus Bend Member 3 constitutes the modem depositional system of the lower Colorado River and represents the last millennium. Late Pleistocene and Holocene allostratigraphic units and bounding disconformities in the upper Colorado drainage and through the lower Colorado valley correlate with independently-identified changes in climate, vegetation cover, and the characteristics of upland soil mantles, and are interpreted to reflect a series of morphological and sedimentary responses to changes in the relationship between the discharge regime and the concentration of sediments along valley axes. In the far downstream portion of the lower Colorado valley, allostratigraphic units and bounding disconformities persist but their geometry, or stratigraphic architecture, changes substantially in response to the last glacio-eustatic cycle. In this part of the drainage, genesis of the alluvial sequence is interpreted to reflect adjustments to changes in climate, but sequence architecture reflects the details of the last glacio-eustatic cycle
Author: Michael David Blum
Publisher:
ISBN:
Category : Alluvium
Languages : en
Pages : 572
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Author: Andrew D. Miall
Publisher: Springer
ISBN: 3662032376
Category : Science
Languages : en
Pages : 589
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Book Description
Fluvial deposits represent the preserved record of one of the major nonmarine environ ments. They accumulate in large and small intermontane valleys, in the broad valleys of trunk rivers, in the wedges of alluvial fans flanking areas of uplift, in the outwash plains fronting melting glaciers, and in coastal plains. The nature of alluvial assemblages - their lithofacies composition, vertical stratigraphic record, and architecture - reflect an inter play of many processes, from the wandering of individual channels across a floodplain, to the long-term effects of uplift and subsidence. Fluvial deposits are a sensitive indicator of tectonic processes, and also carry subtle signatures of the climate at the time of deposition. They are the hosts for many petroleum and mineral deposits. This book is about all these subjects. The first part of the book, following a historical introduction, constructs the strati graphic framework of fluvial deposits, step by step, starting with lithofacies, combining these into architectural elements and other facies associations, and then showing how these, in turn, combine to represent distinctive fluvial styles. Next, the discussion turns to problems of correlation and the building of large-scale stratigraphic frameworks. These basin-scale constructions form the basis for a discussion of causes and processes, including autogenic processes of channel shifting and cyclicity, and the larger questions of allogenic (tectonic, eustatic, and climatic) sedimentary controls and the development of our ideas about nonmarine sequence stratigraphy.
Author: Timothy K. Perttula
Publisher: Texas A&M University Press
ISBN: 1603446494
Category : Social Science
Languages : en
Pages : 480
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Book Description
Paleoindians first arrived in Texas more than eleven thousand years ago, although relatively few sites of such early peoples have been discovered. Texas has a substantial post-Paleoindian record, however, and there are more than fifty thousand prehistoric archaeological sites identified across the state. This comprehensive volume explores in detail the varied experience of native peoples who lived on this land in prehistoric times. Chapters on each of the regions offer cutting-edge research, the culmination of years of work by dozens of the most knowledgeable experts. Based on the archaeological record, the discussion of the earliest inhabitants includes a reclassification of all known Paleoindian projectile point types and establishes a chronology for the various occupations. The archaeological data from across the state of Texas also allow authors to trace technological changes over time, the development of intensive fishing and shellfish collecting, funerary customs and the belief systems they represented, long-term changes in settlement mobility and character, landscape use, and the eventual development of agricultural societies. The studies bring the prehistory of Texas Indians all the way up through the Late Prehistoric period (ca. a.d. 700–1600). The extensively illustrated chapters are broadly cultural-historical in nature but stay strongly focused on important current research problems. Taken together, they present careful and exhaustive considerations of the full archaeological (and paleoenvironmental) record of Texas.
Author: Robert A. Morton
Publisher:
ISBN:
Category : Coasts
Languages : en
Pages : 250
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Author: Norman D. Smith
Publisher: John Wiley & Sons
ISBN: 1444304224
Category : Science
Languages : en
Pages : 488
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Book Description
Understanding of rivers and their sediments, both as modern systems and as ancient counterparts in the geological record, has progressed steadily but markedly over the past several decades, with contributions by practitioners in diverse fields of geosciences and engineering. This book contains 31 papers, with authors from 13 countries, who participated in the Sixth International Conference on Fluvial Sedimentology held in Cape Town, South Africa, in 1977. True to the nature of these quadrennial conferences, the papers in this book discuss a broad range of fluvial subjects that include the character of bedforms and sediment transport in river channels, morphological and sedimentological features of modern fluvial environments, modern and ancient avulsions, internal and external controls on the behaviour of river systems, and the facies and architectural organization of alluvial deposits. A specialist volume detailing the latest advances in fluvial sedimentology. Authorship includes the leaders in the field. If you are a member of the International Association of Sedimentologists, for purchasing details, please see: http://www.iasnet.org/publications/details.asp?code=SP28
Author: Gulf Coast Association of Geological Societies
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 596
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Author: Paul A. Carling
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 550
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Book Description
A final chapter provides a brief view of future perspectives.
Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 860
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Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 724
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