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Author: R. Sabadini Publisher: Springer Science & Business Media ISBN: 9401133743 Category : Science Languages : en Pages : 705
Book Description
by K. Lambeck, R. Sabadini and E. B08Chi Viscosity is one of the important material properties of the Earth, controlling tectonic and dynamic processes such as mantle convection, isostasy, and glacial rebound. Yet it remains a poorly resolved parameter and basic questions such as whether the planet's response to loading is linear or non-linear, or what are its depth and lateral variations remain uncertain. Part of the answer to such questions lies in laboratory observations of the rheology of terrestrial materials. But the extrapolation of such measurements from the laboratory environment to the geological environment is a hazardous and vexing undertaking, for neither the time scales nor the strain rates characterizing the geological processes can be reproduced in the laboratory. General rules for this extrapolation are that if deformation is observed in the laboratory at a particular temperature, deformation in geological environments will occur at a much reduced temperature, and that if at laboratory strain rates a particular deformation mechanism dominates over all others, the relative importance of possible mechanisms may be quite different at the geologically encountered strain rates. Hence experimental results are little more than guidelines as to how the Earth may respond to forces on long time scales.
Author: R. Sabadini Publisher: Springer Science & Business Media ISBN: 9401133743 Category : Science Languages : en Pages : 705
Book Description
by K. Lambeck, R. Sabadini and E. B08Chi Viscosity is one of the important material properties of the Earth, controlling tectonic and dynamic processes such as mantle convection, isostasy, and glacial rebound. Yet it remains a poorly resolved parameter and basic questions such as whether the planet's response to loading is linear or non-linear, or what are its depth and lateral variations remain uncertain. Part of the answer to such questions lies in laboratory observations of the rheology of terrestrial materials. But the extrapolation of such measurements from the laboratory environment to the geological environment is a hazardous and vexing undertaking, for neither the time scales nor the strain rates characterizing the geological processes can be reproduced in the laboratory. General rules for this extrapolation are that if deformation is observed in the laboratory at a particular temperature, deformation in geological environments will occur at a much reduced temperature, and that if at laboratory strain rates a particular deformation mechanism dominates over all others, the relative importance of possible mechanisms may be quite different at the geologically encountered strain rates. Hence experimental results are little more than guidelines as to how the Earth may respond to forces on long time scales.
Author: Lawrence M. Cathles Publisher: ISBN: 9780691617831 Category : Science Languages : en Pages : 0
Book Description
Approximately 12,000 years ago, at the end of the last ice age, the three kilometers of ice that covered Canada, the large European glaciers in Fennoscandia and Siberia, and many other minor glaciers melted quickly. The resulting meltwaters increased the depth of the world's oceans by about 110 meters. The earth's response to this redistribution of loads was one of fluid flow. By studying the way in which that flow occurred, much can be learned about the viscosity structure of the earth's mantle: that is, how the fluid properties of the earth vary with depth. In this volume Lawrence M. Cathles III sets out to lay the theoretical foundations necessary to model the isostatic (fluid) adjustment of a self-gravitating viscoelastic sphere, such as the earth, and to use these foundations, together with geological evidence of the way the earth responded to the pleistocene land redistributions, to study the viscosity of the mantle. The author argues that the viscosity of the entire mantle is very close to 1022 poise, except for a low-viscosity channel, about 75 kilometers thick, in the uppermost mantle. This conclusion differs sharply from the common view that the earth's mantle becomes very viscous (1027 poise) below a depth of about 1000 kilometers. Originally published in 1975. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.
Author: Patrick Wu Publisher: Trans Tech Publications Ltd ISBN: 3035739870 Category : Technology & Engineering Languages : en Pages : 656
Book Description
Although the last Ice Age ended about ten thousand years ago, its effects are still influencing human activities today - for example: coastal engineering, siting of nuclear waste depositories, intraplate earthquake mitigation, inaccuracy of a global positioning due to changes in the Geodetic Reference Frame, etc. The recognition of Ice Ages and glacial isostasy led to the first scientific revolution in earth science. During the last few decades, studies of the Dynamics of the Ice Age Earth have brought together various disciplines - including geomorphology, geodynamics, rock and ice rheology, geodesy, glaciology, oceanography, climatology, astronomy, engineering and archeology.Recent interest in the subject has surged forward due to new advances in space-age geodetic techniques and new developments in modeling methods.
Author: David Hopley Publisher: Springer Science & Business Media ISBN: 904812638X Category : Science Languages : en Pages : 1226
Book Description
Coral reefs are the largest landforms built by plants and animals. Their study therefore incorporates a wide range of disciplines. This encyclopedia approaches coral reefs from an earth science perspective, concentrating especially on modern reefs. Currently coral reefs are under high stress, most prominently from climate change with changes to water temperature, sea level and ocean acidification particularly damaging. Modern reefs have evolved through the massive environmental changes of the Quaternary with long periods of exposure during glacially lowered sea level periods and short periods of interglacial growth. The entries in this encyclopedia condense the large amount of work carried out since Charles Darwin first attempted to understand reef evolution. Leading authorities from many countries have contributed to the entries covering areas of geology, geography and ecology, providing comprehensive access to the most up-to-date research on the structure, form and processes operating on Quaternary coral reefs.
Author: Mark Asch Publisher: SIAM ISBN: 1611974542 Category : Mathematics Languages : en Pages : 310
Book Description
Data assimilation is an approach that combines observations and model output, with the objective of improving the latter. This book places data assimilation into the broader context of inverse problems and the theory, methods, and algorithms that are used for their solution. It provides a framework for, and insight into, the inverse problem nature of data assimilation, emphasizing why and not just how. Methods and diagnostics are emphasized, enabling readers to readily apply them to their own field of study. Readers will find a comprehensive guide that is accessible to nonexperts; numerous examples and diverse applications from a broad range of domains, including geophysics and geophysical flows, environmental acoustics, medical imaging, mechanical and biomedical engineering, economics and finance, and traffic control and urban planning; and the latest methods for advanced data assimilation, combining variational and statistical approaches.
Author: Colin V. Murray-Wallace Publisher: Cambridge University Press ISBN: 0521820839 Category : Nature Languages : en Pages : 503
Book Description
An important overview of Quaternary climates including detailed Pleistocene and Holocene sea-level changes, for researchers and graduate and advanced undergraduate students.
Author: Evan James Gowan Publisher: ISBN: Category : Languages : en Pages :
Book Description
In the late Pleistocene, most of British Columbia and northern Washington was covered by the Cordilleran ice sheet. The weight of the ice sheet caused up to several hundred metres of depression of the Earth's crust. This caused relative sea level to be higher in southwestern British Columbia despite lower global eustatic sea level. After deglaciation, postglacial rebound of the crust caused sea level to quickly drop to below present levels. The rate of sea-level fall is used here to determine the rheology of the mantle in southwestern British Columbia. The first section of this study deals with determination of the postglacial sea-level history in the Victoria area. Constraints on sea-level position come from isolation basin cores collected in 2000 and 2001, as well as from previously published data from the past 45 years. The position of sea-level is well constrained at elevations greater than -4 m, and there are only loose constraints below that. The highstand position in the Victoria area is between 75-80 m. Sea level fell rapidly from the highstand position to below 0 m between 14.3 and 13.2 thousand calendar years before present (cal kyr BP). The magnitude of the lowstand position was between -11 and -40 m. Though there are few constraints on the lowstand position, analysis of the crustal response favours larger lowstand. Well constrained sea-level histories from Victoria, central Strait of Georgia and northern Strait of Georgia are used to model the rheology of the mantle in southwestern British Columbia. A new ice sheet model for the southwestern Cordillera was developed as older models systematically underpredicted the magnitude of sea level in late glacial times. Radiocarbon dates are compiled to provide constraints on ice sheet advance and retreat. The Cordillera ice sheet reached maximum extent between 17 and 15.4 cal kyr BP. After 15.4 cal kyr, the ice sheet retreated, and by 13.7 cal kyr BP Puget Sound, Juan de Fuca Strait and Strait of Georgia were ice free. By 10.7 cal kyr BP, ice was restricted to mountain glaciers at levels similar to present. With the new ice model, and using an Earth model with a 60 km lithosphere, asthenosphere with variable viscosity and thickness, and transitional and lower mantle viscosity based on the VM2 Earth model, predicted sea level matches the observed sea level constraints in southwestern British Columbia. Nearly identical predicted sea-level curves are found using asthenosphere thicknesses between 140-380 km with viscosity values between 3x10^18 and 4x10^19 Pa s. Predicted sea level is almost completely insensitive to the mantle below the asthenosphere. Modeled present day postglacial uplift rates are less than 0.5 mm yr^-1. Despite the tight fit of the predicted sea level to observed late-glacial sea level observations, the modelling was not able to fit the early Holocene rise of sea level to present levels in the central and northern Strait of Georgia.
Author: Kevin Karl Belanger Publisher: ISBN: Category : Languages : en Pages :
Book Description
New relative sea-level (RSL) observations dating from the late Pleistocene and early Holocene, during and after the collapse of the Cordilleran ice-sheet (CIS), are provided for two regions in southern coastal British Columbia. They record the glacial isostatic adjustment (GIA) response of the Earth to the changing surface load of the waning CIS. The data provide a new RSL curve for Sechelt, on the mainland coast north of Vancouver, and extend and revise a previously constructed curve for Barkley Sound on the west coast of Vancouver Island. The observations create a new profile of RSL curves oriented southwest-northeast across Vancouver Island and the Strait of Georgia. A previously-defined profile of RSL curves is oriented northwest-southeast profile along the east coast of Vancouver Island. The two profiles intersect in the central Strait of Georgia. The new RSL curves sample different parts of the Cascadia Subduction Zone (CSZ) and provide constraints on the history of the CIS. The Juan de Fuca plate subducts beneath the North American plate in roughly the same southwest to northeast direction as the RSL profile. GIA modelling of the RSL observations along this profile may indicate spatial variations related to the structure of the Cascadia Subduction Zone (CSZ). The CIS flowed roughly from northeast to southwest over the regions of interest. RSL observations along this path indicate how sea-level change differed with distance from the edge of the ice-sheet towards its centre. The CIS model of James et al. (2009b) is refined to fit observed sea levels while applying glacial geological constraints to regional ice sheet advance and retreat. Sea level in Barkley Sound dropped from greater than 27 m elevation before 15 cal kyr BP to -46 m below present around 12 cal kyr BP. At Sechelt, sea level closely follows the same trend as in the central Strait of Georgia, dropping from over 150 m before 14 cal kyr BP and falling past present levels after 12.4 cal kyr BP to a poorly constrained lowstand between 12 and 9 cal kyr BP. The initial crustal uplift rate near Sechelt was at least 85 mm/yr, comparable to that of the central Strait of Georgia. The sea-level observations are best fit with predictions employing an Earth model with a 60-km effective lithosphere thickness and asthenospheric viscosity and thickness of 4 ? 1019 Pa s and 380 km, respectively. The transition zone and lower mantle viscosities are based on the VM2 Earth model (Peltier 2002). Sea level in Barkley Sound fell quickly (15-30 mm/yr), and observed sea level is best fit with the same asthenospheric viscosity, but with a thinner 30-km thick lithosphere, consistent with the regional tectonic structure. Revisions to the ice model are consistent with radiocarbon constraints on ice sheet history and provide good agreement with the observed sea-level history for the study regions as well as RSL histories previously described for the Strait of Georgia and southern Vancouver Island.
Author: R. Sabadini
Author: R. Sabadini
Author: Lawrence M. Cathles
Author: Patrick Wu
Author: David Hopley
Author: John T. Andrews
Author: Mark Asch
Author: W. R. Peltier
Author: Colin V. Murray-Wallace
Author: Evan James Gowan
Author: Kevin Karl Belanger