Lake Washburn (Antarctica)
Location of the former lake
Lake Washburn was located in Taylor Valley, McMurdo Dry Valleys. It either covered the southwestern part of the valley where Lake Bonney now lies,[1] or the northeastern part above present-day Lake Fryxell;[2] the present-day lakes in Taylor Valley may be remnants of Lake Washburn.[3] The former lake was named in 1960 after Albert Lincoln Washburn.[4]
It was probably dammed by ice that filled the northwestern part of Taylor Valley,[1] when the Ross Ice Shelf expanded during the Last Glacial Maximum. Depending on how much the ice shelf expanded, two different sizes of the lakes are possible,[5] the smaller of which would have been limited to the Lake Bonney basin[6] at the western end of the valley.[7] Delta deposits that were reinterpreted as river deposits and salt accumulations below the maximum lake levels point to a small size of Lake Washburn[8] as do the properties of soils around the hypothesized shorelines,[9] while soil carbonates[10] and the presence of unfrozen groundwater in the area that would have been covered by a large Lake Washburn implies a large size.[7] The lake extended into Hjorth Valley.[11]
Water levels reached an elevation of 300–336 metres (984–1,102 ft) and its shores featured
Chronology and disappearance
The ice dam existed between 23,000-8,340
It left carbonates[21] and lake sediments in the Taylor Valley; organic matter in these sediments constitutes an important component of and organic matter input the present-day soils in the valley[22] while the presence of non-marine diatoms in the sediments demonstrates that they were not deposited by the sea.[23] The Alpine I Drift from later glacial advances overlies the Lake Washburn deposits.[24] Local springtail populations bear imprints of the former existence of the lake.[25] Later water level fluctuations in the valleys could have caused the lakes to dry out and overspill.[26]
Geographical and climatic context
The McMurdo Dry Valleys are presently unglaciated, as the Transantarctic Mountains block glaciers and moisture from reaching the valleys. Despite mean temperatures of −30 – −14.8 °C (−22.0–5.4 °F), meltwater from glaciers supply fresh water to the valleys, where it forms closed lakes (lakes without an outflow) that are perennially ice-covered.[27] During December and January, meltwater flows from the glaciers to the lakes.[5] Occasionally, during summer strong winds blow from the Antarctic Ice Sheet through the valleys to the sea; these winds warm as they descend into the valleys and can melt the ice, causing water levels to rise.[28]
There is evidence that during the
Precise dating of these paleolakes is rendered difficult, however, by the rarity of dateable deposits and the unreliability of
References
- ^ a b Obryk et al. 2017, p. 458.
- ^ a b Nolan et al. 2006, p. 813.
- ^ Wagner et al. 2011, p. 307.
- ^ Péwé 1960, p. 507.
- ^ a b c d e Obryk et al. 2017, p. 459.
- ^ a b Myers et al. 2021, p. 3578.
- ^ a b Mikucki et al. 2015, p. 5.
- ^ a b Levy et al. 2017, p. 1073.
- ^ Bockheim, Campbell & McLeod 2008, p. 151.
- ^ Foley et al. 2006, p. 89.
- ^ Hall & Denton 2000, p. 330.
- ^ Nolan et al. 2006, p. 817.
- ^ Hall, Hendy & Denton 2006, p. 148.
- ^ Hall, Denton & Hendy 2000, p. 298.
- ^ Hall, Denton & Hendy 2000, p. 301.
- ^ Konfirst et al. 2011, p. 264.
- ^ Wagner et al. 2006, p. 321.
- ^ Wagner et al. 2006, p. 335.
- ^ Wagner et al. 2011, p. 316.
- ^ Hall & Denton 2000, p. 334.
- ^ Stumpf et al. 2012, p. 80.
- ^ Barrett et al. 2004, p. 3107.
- ^ Wagner et al. 2006, p. 320.
- ^ Hall, Denton & Hendy 2000, p. 278.
- ^ Nolan et al. 2006, p. 818.
- ^ Myers et al. 2021, p. 3591.
- ^ a b c Obryk et al. 2017, p. 457.
- ^ Obryk et al. 2017, p. 460.
- ^ Stuiver et al. 1981, p. 366.
- ^ Obryk et al. 2017, p. 461.
- ^ Levy et al. 2017, p. 1071.
- ^ Konfirst et al. 2011, p. 258.
- ^ Levy et al. 2017, p. 1082.
- ^ a b Konfirst et al. 2011, p. 265.
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- Bockheim, J. G.; Campbell, I. B.; McLeod, M. (15 July 2008). "Use of soil chronosequences for testing the existence of high-water-level lakes in the McMurdo Dry Valleys, Antarctica". CATENA. 74 (2): 144–152. ISSN 0341-8162.
- Foley, Kelly K.; Lyons, W. Berry; Barrett, John E.; Virginia, Ross A. (1 January 2006). "Pedogenic carbonate distribution within glacial till in Taylor Valley, Southern Victoria Land, Antarctica". Paleoenvironmental Record and Applications of Calcretes and Palustrine Carbonates. ISBN 9780813724164.
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