Download or read book Surface Exposure Dating of Glacial Deposits from the Last Glacial Cycle written by Anne U. Reuther and published by . This book was released on 2007 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Surface Exposure Geochronology Using Cosmogenic Nuclides written by Edward Jeremy Brook and published by . This book was released on 1993 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cosmogenic 3He, 26A1, and 10Be have been measured in a variety of Antarctic glacial deposits in the McMurdo Sound-Dry Valleys region. The goals of this project were to provide age constraints for Antarctic glacial events, to investigate production mechanisms of 3He, lOBe, and 26 A1 in terrestrial rocks, to constrain the importance of loss of 3He from quartz due to diffusion, and to refine methods of exposure-age dating. Moraines deposited in Arena Valley by the Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, have exposure ages from ~120 kyr to 2 myr. 10Be and 3He ages of 122 ± 29 and 134 ±54 kyr, respectively, for the Taylor II moraine are consistent with deposition during isotope stage Se (~ 120 kyr) and with aerial expansions of the East Antarctic Ice Sheet during interglacial periods. Mean 10Be exposure ages for older moraines in the valley are 362 ± 26 kyr (Taylor III), 1.1 ± 0.1 myr (Taylor IVa) and 1.9 ± 0.1 myr (Taylor IVb). Because these older moraines were deposited at most ~200m above the Taylor II limit their ages suggest that major ice sheet advances during the last 2 myr have been broadly similar in magnitude to changes during the last glacial-interglacial cycle. 10Be ages for stratigraphically older drift deposited by the Taylor Glacier allow extension of this conclusion to ~ 3 myr. lOBe measurements in high altitude, pre-Pleistocene glacial deposits in the Dry Valleys preclude rapid uplift of the Transantarctic Mountains (400-1000 m/myr) suggested by controversial biostratigraphic studies of Sirius Group tills. Comparison of measured lOBe concentrations in Sirius Group deposits with those predicted with a model of the effects of uplift on 10Be production suggests minimal uplift of the Transantarctic Mountains over the last 3 myr. 3He, 10Be and 26A1 ages for the "late Wisconsin" Ross Sea Drift, a glacial drift deposited on the coast of McMurdo Sound by the Ross Sea Ice Sheet, range from 8-106 kyr. The age range suggests that this deposit does not, as previous studies suggested, represent a single ice advance in response to lowered sea level at the last glacial maximum. The age range may reflect several ice sheet advances during the last glacial period. Paired measurements of 3He and 10Be in a number of quartz sandstones from the Dry Valleys region show that cosmogenic 3He is not completely retained on time scales of greater than 200 kyr. The 3He and 10Be data, combined with measurements of 3He concentrations in quartz as a function of grain size, suggest effective 3He diffusion coefficients in quartz from ~10-19 to 10-17 cm2 s-1. These values are one to three orders of magnitude greater than previous experimental determinations extrapolated to low temperature. The data also suggest that 3He diffusion rates in quartz do not follow simple volume diffusion trends and are probably sample dependent. Crushing quartz grains in vacuo releases variable concentrations of 3He and 4He and releases helium with surprisingly high isotopic compositions, up to 148 x Ra (Ra = atmospheric 3He/4He ratio: 1.384 x 10-6). The high ratios suggest that crushing releases cosmogenic 3He. As a result, in vacuo crushing cannot be used to correct 3He concentrations in quartz for a magmatic or "non-cosmogenic" component, as is possible in olivine and clinopyroxene phenocrysts in volcanic rocks. Replicate analyses of quartz samples show widely varying 4He concentrations and constant 3He concentrations. These data allow constraint of the nucleogenic 3He/4He production ratio to less than 0.05 ± 0.2 Ra. Corrections to exposure ages for nucleogenic 3He are in most cases

Download or read book Quaternary Glaciation in the Mediterranean Mountains written by P.D. Hughes and published by Geological Society of London. This book was released on 2017-01-30 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mountains of the Mediterranean world are now largely ice free, but many were repeatedly glaciated during the Quaternary ice age. This created spectacular glaciated landscapes with a rich array of glacial deposits and landforms. The glacial and glacio-fluvial records are often very well preserved and our understanding of the timing of Quaternary glaciation has very recently been transformed through the application of dating methods utilizing uranium-series and cosmogenic isotopes. Glacial records from the Mediterranean now boast some of the most robust chronologies for mountain glaciation anywhere in the world – they represent a unique archive of Quaternary environmental change of global significance. The southerly latitude and relatively small size of Mediterranean glaciers rendered them especially sensitive to Pleistocene and Holocene climate changes. This volume brings together the leading researchers and the latest research on Mediterranean glaciation. Several papers also explore glacier behaviour in the Holocene – including those glaciers of southernmost Europe at risk of disappearing this century.

Download or read book Quaternary Glaciations Extent and Chronology written by J. Ehlers and published by Elsevier. This book was released on 2011-08-17 with total page 1128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents an up-to-date, detailed overview of the Quaternary glaciations all over the world, not only with regard to stratigraphy but also with regard to major glacial landforms and the extent of the respective ice sheets. The locations of key sites are included. The information is presented in digital, uniformly prepared maps which can be used in a Geographical Information System (GIS) such as ArcView or ArcGIS. The accompanying text supplies the information on how the data were obtained (geomorphology, geological mapping, air photograph evaluation, satellite imagery), how the features were dated (14C, TL, relative stratigraphy) and how reliable they are supposed to be. All references to the underlying basic publications are included. Where controversial interpretations are possible e.g. in Siberia or Tibet, this is pointed out. As a result, the information on Quaternary glaciations worldwide will be much improved and supplied in a uniform digital format. The information on the glacial limits is compiled in digital form by the coordinators of the project, and is available for download at: http://booksite.elsevier.com/9780444534477/ Completely updated detailed coverage of worldwide Quaternary glaciations Information in digital, uniformly prepared maps which can be used in a GIS such as ArcView or ArcGis Step-by-step guideline how to open and use ArcGis files Possibility to convert the shapefiles into GoogleEarth kmz-files Availability of chronological controls

Download or read book Glacial Deposits written by Richard Parker Goldthwait and published by Dowden Hutchinson and Ross. This book was released on 1975 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reprints of the most illuminating original writings on glacial deposits, particularly concerned with process and origin.

Download or read book Cosmogenic Exposure age Chronologies of Pinedale and Bull Lake Glaciations in Greater Yellowstone and the Teton Range US written by Joseph M. Licciardi and published by . This book was released on 2008 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have obtained 69 new cosmogenic 10Be surface exposure ages from boulders on moraines deposited by glaciers of the greater Yellowstone glacial system and Teton Range during the middle and late Pleistocene. These new data, combined with 43 previously obtained 3He and 10Be ages from deposits of the northern Yellowstone outlet glacier, establish a high-resolution chronology for the Yellowstone?Teton mountain glacier complexes. Boulders deposited at the southern limit of the penultimate ice advance of the Yellowstone glacial system yield a mean age of 136±1310Be ka and oldest ages of ~151-15710Be ka. These ages support a correlation with the Bull Lake of West Yellowstone, with the type Bull Lake of the Wind River Range, and with Marine Isotope Stage (MIS) 6. End moraines marking the maximum Pinedale positions of outlet glaciers around the periphery of the Yellowstone glacial system range in age from 18.8±0.9 to 16.5±1.410Be ka, and possibly as young as 14.6±70.710Be ka, suggesting differences in response times of the various ice-cap source regions. Moreover, all dated Pinedale terminal moraines in the greater Yellowstone glacial system post-date the Pinedale maximum in the Wind River Range by ~4-6 kyr, indicating a signi?cant phase relationship between glacial maxima in these adjacent ranges. Boulders on the outermost set and an inner set of Pinedale end moraines enclosing Jenny Lake on the eastern Teton front yield mean ages of 14.6±0.7 and 13.5±1.110Be ka, respectively. The outer Jenny Lake moraines are partially buried by outwash from ice on the Yellowstone Plateau, hence their age indicates a major standstill of an expanded valley glacier in the Teton Range prior to the Younger Dryas, followed closely by deglaciation of the Yellowstone Plateau. These new glacial chronologies are indicative of spatially variable regional climate forcing and temporally complex patterns of glacier responses in this region of the Rocky Mountains during the Pleistocene.

Download or read book Man and the Glacial Period written by George Frederick Wright and published by . This book was released on 1892 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the cause date and duration of the last glacial epoch of geology and the probable antiquity of man With an investigation of a new movement of the earth written by Alfred Wilks Drayson and published by . This book was released on 1873 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Cause Date and Duration of the Last Glacial Epoch of Geology and the Probable Antiquity of Man written by Alfred Wilks Drayson and published by . This book was released on 1873 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Antarctic Glacial Chronology written by Robert P. Ackert and published by . This book was released on 2000 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface exposure dating, using the concentration of cosmogenic nuclides (3He, 21Ne, and 36Cl) in moraine boulders, combined with mapping of glacial moraines from three key locations, is used to provide new constraints to Antarctic glacial chronology. The results are used to reconstruct past West Antarctic Ice Sheet (WAIS) geometry and test models of WAIS behavior. Mount Waesche is a volcanic nunatak near the dome of the WAIS in Marie Byrd Land. The Dominion Range is at the head of the Beardmore Glacier, an outlet glacier of the East Antarctic Ice Sheet in the Transantarctic Mountains. Dromedary Platform is a bench along the Koettlitz Glacier which flows into southern McMurdo Sound. In addition, a new 3He production rate calibration, and determination of initial 3He/4He in Ferrar Dolerite and Beacon Sandstone, substantially reduce uncertainties in Antarctic exposure ages. 3He production rates of 129 ± 4 atoms/g/yr (olivine) and 124 ± 4 atoms/g/yr (clinopyroxene) at sea level, high latitude, are determined from an independently dated 125 ka lava flow in Patagonia (46°S). Paired 3He and 36Cl measurements are consistent with negligible surface erosion which is inferred from flow morphology. These mid-latitude, long term, 3He production rates reduce uncertainties previously introduced when scaling production rates calibrated at lower latitudes to Antarctica. The results also confirm the compositional dependence of 3He production rates predicted by theoretical calculations and are used to scale the production rates to quartz. Determinations of initial 3He/4He in pyroxene from shielded dolerite and by incremental heating of quartz show that inherited (nucleogenic) 3He concentrations are very low (3He/4He

Download or read book Quaternary Dating Methods written by Mike Walker and published by John Wiley & Sons. This book was released on 2013-04-30 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This introductory textbook introduces the basics of dating, the range of techniques available and the strengths and limitations of each of the principal methods. Coverage includes: the concept of time in Quaternary Science and related fields the history of dating from lithostratigraphy and biostratigraphy the development and application of radiometric methods different methods in dating: radiometric dating, incremental dating, relative dating and age equivalence Presented in a clear and straightforward manner with the minimum of technical detail, this text is a great introduction for both students and practitioners in the Earth, Environmental and Archaeological Sciences. Praise from the reviews: "This book is a must for any Quaternary scientist." SOUTH AFRICAN GEOGRAPHICAL JOURNAL, September 2006 “...very well organized, clearly and straightforwardly written and provides a good overview on the wide field of Quaternary dating methods...” JOURNAL OF QUATERNARY SCIENCE, January 2007

Download or read book The Ice Age in North America written by George Frederick Wright and published by . This book was released on 1911 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the Cause Date and Duration of the Last Glacial Epoch of Geology written by Drayson and published by BoD – Books on Demand. This book was released on 2023-07-12 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reprint of the original, first published in 1873.

Download or read book Cosmogenic Nuclides written by Tibor J. Dunai and published by Cambridge University Press. This book was released on 2010-03-04 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to provide a comprehensive and state-of-the-art introduction to the novel and fast-evolving topic of in-situ produced cosmogenic nuclides. It presents an accessible introduction to the theoretical foundations, with explanations of relevant concepts starting at a basic level and building in sophistication. It incorporates, and draws on, methodological discussions and advances achieved within the international CRONUS (Cosmic-Ray Produced Nuclide Systematics) networks. Practical aspects such as sampling, analytical methods and data-interpretation are discussed in detail and an essential sampling checklist is provided. The full range of cosmogenic isotopes is covered and a wide spectrum of in-situ applications are described and illustrated with specific and generic examples of exposure dating, burial dating, erosion and uplift rates, and process model verification. Graduate students and experienced practitioners will find this book a vital source of information on the background concepts and practical applications in geomorphology, geography, soil-science, and geology.

Download or read book Preservation and Sediment Cycling Beneath Ghost Glaciers written by Lee Corbett and published by . This book was released on 2016 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Constraining past episodes of climate change and glacial response is critical for understanding future impacts of climate change, especially in the high latitudes where warming is expected to be rapid and most of Earth’s glaciers exist. Many studies of past glacier size utilize rare isotopes called cosmogenic nuclides to perform surface exposure dating. Since most areas of Earth’s surface that were previously glaciated were covered by erosive ice, which stripped away pre-existing cosmogenic nuclides, surface exposure dating yields the timing of the most recent deglaciation. However, in some high latitude areas where glacial ice is cold-based and non-erosive (so-called “ghost glaciers”), the assumptions of surface exposure dating are violated. Alternate approaches are required to constrain the complex histories of such landscapes. My doctoral dissertation focuses on both developing and employing alternative approaches to studying glacial history in the high latitudes, where glacial ice is non-erosive and dating rock surfaces with a single cosmogenic nuclide does not yield exposure ages. Here, I utilize optimized laboratory methods, paired analyses of two cosmogenic isotopes (10Be and 26Al), numerical models to assess possible exposure/burial histories, and Monte Carlo simulations to constrain uncertainties. To study the exposure and burial history of long-preserved landscapes in the Arctic, I investigate landscapes in two high-latitude locations: Thule, northwestern Greenland; and Cumberland Sound, southern Baffin Island, Canada. Bedrock surfaces, sampled on Baffin Island, exhibit evidence of long-lived subaerial weathering and have simple 10Be exposure ages up to 160,000 yr, despite being glaciated until ~10,000 yr. Simple exposure ages tend to increase with elevation, suggesting more effective erosion in the fjords and longer-term preservation of the uplands. Minimum limiting total histories calculated with 26Al/10Be range up to several million years, with periods of exposure representing ~20% of the total history, describing surfaces that have been alternately preserved beneath non-erosive glacial ice and weathered subaerially over many glacial/interglacial cycles. Boulders, sampled at both sites, have simple 10Be exposure ages up to 78,000 yr in Thule and 79,000 yr on Baffin Island, and yield multi-modal age distributions. Simple exposure ages of boulders tend to under-estimate bedrock ages in the cases of paired bedrock/boulder samples. Minimum limiting total histories calculated with 26Al/10Be range up to 700,000 yr in Thule and several million years on Baffin Island, with periods of exposure representing only a small portion of the total history. Forward numerical models suggest that boulders have been repeatedly reworked, likely experiencing partial or complete shielding during interglacial periods because of rotation and/or burial by till. The landscapes I assess here preserve histories of hundreds of thousands to millions of years, and represent a complex interplay of interglacial exposure, subglacial preservation beneath cold-based ice, periglacial processes, and subaerial weathering. Although such landscapes represent methodological challenges, they contain valuable information about long-term variations in glacial extent and climate.

Download or read book Encyclopedia of Snow Ice and Glaciers written by Vijay P. Singh and published by Springer Science & Business Media. This book was released on 2011-06-29 with total page 1301 pages. Available in PDF, EPUB and Kindle. Book excerpt: The earth’s cryosphere, which includes snow, glaciers, ice caps, ice sheets, ice shelves, sea ice, river and lake ice, and permafrost, contains about 75% of the earth’s fresh water. It exists at almost all latitudes, from the tropics to the poles, and plays a vital role in controlling the global climate system. It also provides direct visible evidence of the effect of climate change, and, therefore, requires proper understanding of its complex dynamics. This encyclopedia mainly focuses on the various aspects of snow, ice and glaciers, but also covers other cryospheric branches, and provides up-to-date information and basic concepts on relevant topics. It includes alphabetically arranged and professionally written, comprehensive and authoritative academic articles by well-known international experts in individual fields. The encyclopedia contains a broad spectrum of topics, ranging from the atmospheric processes responsible for snow formation; transformation of snow to ice and changes in their properties; classification of ice and glaciers and their worldwide distribution; glaciation and ice ages; glacier dynamics; glacier surface and subsurface characteristics; geomorphic processes and landscape formation; hydrology and sedimentary systems; permafrost degradation; hazards caused by cryospheric changes; and trends of glacier retreat on the global scale along with the impact of climate change. This book can serve as a source of reference at the undergraduate and graduate level and help to better understand snow, ice and glaciers. It will also be an indispensable tool containing specialized literature for geologists, geographers, climatologists, hydrologists, and water resources engineers; as well as for those who are engaged in the practice of agricultural and civil engineering, earth sciences, environmental sciences and engineering, ecosystem management, and other relevant subjects.

Download or read book Antarctic Glacial Chronology New Constraints from Surface Exposure Dating written by and published by . This book was released on 2000 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface exposure dating using 3He, Ne-21 and Cl-36 combined with mapping of moraines, provide new constraints on West Antarctic Ice Sheet (WAIS) chronology. New He-3 production rates are determined from a 125 ka lava flow. Measurements of inherited He-3/He-4 in two common Antarctic lithologies allow measurement of exposure ages 6000 years. At Mt. Waesche, a moraine band records interior WAIS elevations higher than present. Surface exposure ages indicate that the last ice highstand occurred 10 +/- 1 ka. The data constrain past WAIS behavior and ice volume. Surface exposure ages place age constraints on six Beardmore Glacier drifts. Two drifts record damming of the glacier during the last glacial maximum (10-20 ka) by an expanded WAIS. The four older drifts record similar damming by the WAIS approx. 600 ka, approx. 1 Ma, and approx. 2 Ma. Moraines of Koettlitz Glacier also record damming by the WAIS prior to the LGM. The oldest moraines are 400 ka. Independent stratigraphic control allows evaluation of prior exposure, cover and determination of erosion rates. Taken together, the results are consistent with sea level control of WAIS extent; the WAIS probably has fluctuated synchronously with the Northern Hemisphere ice sheets for at least the last 1 million years.