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Brenda L. Hall - One of the best experts on this subject based on the ideXlab platform.
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Late Cenozoic paleoenvironment in southern Victoria Land, Antarctica, based on a polar Glaciolacustrine Deposit in western Victoria Valley
Geological Society of America Bulletin, 2002Co-Authors: Meredith A. Kelly, George H. Denton, Brenda L. HallAbstract:Situated in the Transantarctic Mountains, western Victoria Valley is in a key position to test the late Cenozoic stability of the East Antarctic Ice Sheet, as well as that of the surrounding landscape surface. Victoria drift, which covers most of western Victoria Valley, represents a peculiar yet common type of Deposit in the region. The sedimentology of Victoria drift is dominated by loose, sorted material, which preserves lacustrine algae, quite unlike tills in the Dry Valleys. Ridges characterize its morphology. Extraordinarily old ridges and mounds as well as fresh features and unweathered and perched boulders occur without apparent order. Accelerator Mass Spectrometry (AMS) radiocarbon dates of algae from within Victoria drift range from 11;th054 ± 95 to >45;th000 14 C yr B.P. and are not arrayed in chronological order across the drift sheet. Resting on a Miocene erosion surface, Victoria drift is the only widespread Deposit in western Victoria Valley younger than ca. 14 Ma. One hypothesis is that the drift consists of moraines. The strength of this hypothesis is that it explains the arcuate form of many ridges. However, it does not explain the sedimentology, weathering characteristics, or radiocarbon dates. A second hypothesis is that Victoria drift is a unique polar Glaciolacustrine sediment facies Deposited by a “lake-ice conveyer.” The morphologic features, sedimentology, weathering characteristics, and radiocarbon dates of the drift are all consistent with Deposition in a perennially ice-covered lake. This second hypothesis implies polar glacial conditions during Deposition of the drift sheet in order to maintain a permanently ice-covered proglacial lake.
Meredith A. Kelly - One of the best experts on this subject based on the ideXlab platform.
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Late Cenozoic paleoenvironment in southern Victoria Land, Antarctica, based on a polar Glaciolacustrine Deposit in western Victoria Valley
Geological Society of America Bulletin, 2002Co-Authors: Meredith A. Kelly, George H. Denton, Brenda L. HallAbstract:Situated in the Transantarctic Mountains, western Victoria Valley is in a key position to test the late Cenozoic stability of the East Antarctic Ice Sheet, as well as that of the surrounding landscape surface. Victoria drift, which covers most of western Victoria Valley, represents a peculiar yet common type of Deposit in the region. The sedimentology of Victoria drift is dominated by loose, sorted material, which preserves lacustrine algae, quite unlike tills in the Dry Valleys. Ridges characterize its morphology. Extraordinarily old ridges and mounds as well as fresh features and unweathered and perched boulders occur without apparent order. Accelerator Mass Spectrometry (AMS) radiocarbon dates of algae from within Victoria drift range from 11;th054 ± 95 to >45;th000 14 C yr B.P. and are not arrayed in chronological order across the drift sheet. Resting on a Miocene erosion surface, Victoria drift is the only widespread Deposit in western Victoria Valley younger than ca. 14 Ma. One hypothesis is that the drift consists of moraines. The strength of this hypothesis is that it explains the arcuate form of many ridges. However, it does not explain the sedimentology, weathering characteristics, or radiocarbon dates. A second hypothesis is that Victoria drift is a unique polar Glaciolacustrine sediment facies Deposited by a “lake-ice conveyer.” The morphologic features, sedimentology, weathering characteristics, and radiocarbon dates of the drift are all consistent with Deposition in a perennially ice-covered lake. This second hypothesis implies polar glacial conditions during Deposition of the drift sheet in order to maintain a permanently ice-covered proglacial lake.
George H. Denton - One of the best experts on this subject based on the ideXlab platform.
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Late Cenozoic paleoenvironment in southern Victoria Land, Antarctica, based on a polar Glaciolacustrine Deposit in western Victoria Valley
Geological Society of America Bulletin, 2002Co-Authors: Meredith A. Kelly, George H. Denton, Brenda L. HallAbstract:Situated in the Transantarctic Mountains, western Victoria Valley is in a key position to test the late Cenozoic stability of the East Antarctic Ice Sheet, as well as that of the surrounding landscape surface. Victoria drift, which covers most of western Victoria Valley, represents a peculiar yet common type of Deposit in the region. The sedimentology of Victoria drift is dominated by loose, sorted material, which preserves lacustrine algae, quite unlike tills in the Dry Valleys. Ridges characterize its morphology. Extraordinarily old ridges and mounds as well as fresh features and unweathered and perched boulders occur without apparent order. Accelerator Mass Spectrometry (AMS) radiocarbon dates of algae from within Victoria drift range from 11;th054 ± 95 to >45;th000 14 C yr B.P. and are not arrayed in chronological order across the drift sheet. Resting on a Miocene erosion surface, Victoria drift is the only widespread Deposit in western Victoria Valley younger than ca. 14 Ma. One hypothesis is that the drift consists of moraines. The strength of this hypothesis is that it explains the arcuate form of many ridges. However, it does not explain the sedimentology, weathering characteristics, or radiocarbon dates. A second hypothesis is that Victoria drift is a unique polar Glaciolacustrine sediment facies Deposited by a “lake-ice conveyer.” The morphologic features, sedimentology, weathering characteristics, and radiocarbon dates of the drift are all consistent with Deposition in a perennially ice-covered lake. This second hypothesis implies polar glacial conditions during Deposition of the drift sheet in order to maintain a permanently ice-covered proglacial lake.
V. Sivakumar - One of the best experts on this subject based on the ideXlab platform.
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Influence of preparation techniques on the index properties of clay
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 2002Co-Authors: T. Navaneethan, V. SivakumarAbstract:Liquid limit (LL) and plastic limit (PL) are frequently used as indicators of the behaviour of fine-grained materials. These parameters are a prerequisite in every geotechnical investigation. Careful and consistent material preparation is a key component in the laboratory procedures adopted to determine the LL and PL. In preparing samples for such tests, various techniques are used in practice, and this paper examines the influence of these techniques on the actual magnitude of LL and PL measured. The index properties of a Glaciolacustrine Deposit, locally known as Belfast Upper Boulder Clay, which was laid down in glacial Lake Belfast, are examined. The index properties were determined on samples of the material prepared in different ways, including drying the material at two different temperatures (40°C and 110°C), crushing the dried material from coarse granular to fine granular form by adopting varying degrees of crushing effort, and mixing the dry material with both deionised water and tap water. The...
Marit-solveig Seidenkrantz - One of the best experts on this subject based on the ideXlab platform.
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Development of the western Limfjord, Denmark, after the last deglaciation: a review with new data
Bulletin of the Geological Society of Denmark, 2019Co-Authors: Ole Bennike, Niels Nørgaard-pedersen, Jørn Bo Jensen, Katrine Juul Andresen, Marit-solveig SeidenkrantzAbstract:This paper presents new marine evidence of Lateglacial and Holocene environmental changes in the western part of Limfjorden, and provides a review of the geological history/development of this part of northern Jylland, Denmark. Lateglacial clay without fossils is widespread in the region and is probably a Glaciolacustrine Deposit. Limfjorden began to form as a strait in the Early Holocene due to rising relative sea level and the oldest marine shells are dated to c. 9300 cal. years BP. We propose a new relative sealevel curve for the region based on new and published data, which appear to confirm that the relative sea-level change was not extremely rapid, which was suggested earlier. During the Mid-Holocene a wide connection existed from the western part of Limfjorden to the North Sea in the west and more narrow connections existed between Limfjorden and Skagerrak in the north. The marine fauna included several species that indicate warmer and more salty waters than at present. Gradually, the connections to the North Sea and Skagerrak closed due to long-shore sediment transport and Deposition of aeolian sand combined with a fall in the relative sea level during the Middle- to Late Holocene. During the Viking Age, 800–1050 CE (Common Era), the western connection to the North Sea was still open, but around 1200 CE it was closed by a coastal sandy barrier and the western part of Limfjorden became brackish. The coastal barrier was flooded on several occasions but soon formed again. After 1825 CE the western connection from Limfjorden to the North Sea has been maintained artificially.