Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA
The Enchantment Lakes Basin in the Alpine Lakes Wilderness, Washington, preserves two sets of moraines that record distinct post-Wisconsin maximum advances of cirque glaciers in the eastern North Cascades. Cores collected from five lakes adjacent to the moraines indicate that there were two Neoglaci...
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ftwestwashington:oai:cedar.wwu.edu:wwuet-1873 2023-05-15T17:32:37+02:00 Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA Bilderback, Eric L. (Eric Leland) 2004-01-01T08:00:00Z application/pdf https://cedar.wwu.edu/wwuet/850 https://cedar.wwu.edu/cgi/viewcontent.cgi?article=1873&context=wwuet English eng Western CEDAR https://cedar.wwu.edu/wwuet/850 https://cedar.wwu.edu/cgi/viewcontent.cgi?article=1873&context=wwuet Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission. WWU Graduate School Collection Cirque glaciers Eastern North Cascades Neoglacial advances Brynhild moraines Brisingamen moraines Geology text 2004 ftwestwashington 2022-09-14T06:04:01Z The Enchantment Lakes Basin in the Alpine Lakes Wilderness, Washington, preserves two sets of moraines that record distinct post-Wisconsin maximum advances of cirque glaciers in the eastern North Cascades. Cores collected from five lakes adjacent to the moraines indicate that there were two Neoglacial advances, culminating with the Little Ice Age, and one slightly larger advance that ended coincident with the termination of the North Atlantic Younger Dryas event. The cores show no evidence for an early Holocene advance, in contrast to some other studies in the North Cascades, (e.g., Heine, 1998; Thomas, 1997; Thomas et al., 2000). Upstream glacier activity, as indicated by rock-flour production, is recorded in the lake sediments as fluctuations in magnetic susceptibility, organic content, and sediment particle size. Tephra identification, AMS 14C dating, and paleomagnetic secular variation of the sediments provide detailed age constraints for the lake cores. The presence of the 475 cal yr B.P. Mount St. Helens Wn tephra within outwash associated with the inner (Brynhild) moraines indicates that they are Little Ice Age (LIA) equivalent. The age constraints on the lake sediments show that this advance began between ~ 1000-800 cal yr B.P. and culminated after the Wn tephra was deposited. The age of the outer (Brisingamen) moraines, previously reported as early Holocene (Waitt et al.,1982), are instead latest Pleistocene; close limiting 14C dates demonstrate that this advance ended shortly before ~11,300 cal yr B.P., suggesting temporal equivalence with the North Atlantic Younger Dryas climatic reversal (12,940 ± 260 - 11,640 ± 250 cal yr B.P; Alley et al., 1993). A ~500-yr interval of high rock-flour flux in the cores records an early Neoglacial advance between ~3300 and ~2800 cal yr B.P. that was less extensive than the subsequent LIA advance. Steady-state equilibrium-line altitudes (ELAs) for Brynhild and Brisingamen advances estimated with accumulation-area ratio and balance-ratio methods are distinct but nearly ... Text North Atlantic Western Washington University: CEDAR (Contributing to Education through Digital Access to Research) Heine ENVELOPE(167.450,167.450,-78.083,-78.083) High Rock ENVELOPE(-111.452,-111.452,58.917,58.917) |
institution |
Open Polar |
collection |
Western Washington University: CEDAR (Contributing to Education through Digital Access to Research) |
op_collection_id |
ftwestwashington |
language |
English |
topic |
Cirque glaciers Eastern North Cascades Neoglacial advances Brynhild moraines Brisingamen moraines Geology |
spellingShingle |
Cirque glaciers Eastern North Cascades Neoglacial advances Brynhild moraines Brisingamen moraines Geology Bilderback, Eric L. (Eric Leland) Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA |
topic_facet |
Cirque glaciers Eastern North Cascades Neoglacial advances Brynhild moraines Brisingamen moraines Geology |
description |
The Enchantment Lakes Basin in the Alpine Lakes Wilderness, Washington, preserves two sets of moraines that record distinct post-Wisconsin maximum advances of cirque glaciers in the eastern North Cascades. Cores collected from five lakes adjacent to the moraines indicate that there were two Neoglacial advances, culminating with the Little Ice Age, and one slightly larger advance that ended coincident with the termination of the North Atlantic Younger Dryas event. The cores show no evidence for an early Holocene advance, in contrast to some other studies in the North Cascades, (e.g., Heine, 1998; Thomas, 1997; Thomas et al., 2000). Upstream glacier activity, as indicated by rock-flour production, is recorded in the lake sediments as fluctuations in magnetic susceptibility, organic content, and sediment particle size. Tephra identification, AMS 14C dating, and paleomagnetic secular variation of the sediments provide detailed age constraints for the lake cores. The presence of the 475 cal yr B.P. Mount St. Helens Wn tephra within outwash associated with the inner (Brynhild) moraines indicates that they are Little Ice Age (LIA) equivalent. The age constraints on the lake sediments show that this advance began between ~ 1000-800 cal yr B.P. and culminated after the Wn tephra was deposited. The age of the outer (Brisingamen) moraines, previously reported as early Holocene (Waitt et al.,1982), are instead latest Pleistocene; close limiting 14C dates demonstrate that this advance ended shortly before ~11,300 cal yr B.P., suggesting temporal equivalence with the North Atlantic Younger Dryas climatic reversal (12,940 ± 260 - 11,640 ± 250 cal yr B.P; Alley et al., 1993). A ~500-yr interval of high rock-flour flux in the cores records an early Neoglacial advance between ~3300 and ~2800 cal yr B.P. that was less extensive than the subsequent LIA advance. Steady-state equilibrium-line altitudes (ELAs) for Brynhild and Brisingamen advances estimated with accumulation-area ratio and balance-ratio methods are distinct but nearly ... |
format |
Text |
author |
Bilderback, Eric L. (Eric Leland) |
author_facet |
Bilderback, Eric L. (Eric Leland) |
author_sort |
Bilderback, Eric L. (Eric Leland) |
title |
Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA |
title_short |
Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA |
title_full |
Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA |
title_fullStr |
Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA |
title_full_unstemmed |
Timing and Paleoclimatic Significance of Latest Pleistocene and Holocene Cirque Glaciation in the Enchantment Lakes Basin, North Cascades, WA |
title_sort |
timing and paleoclimatic significance of latest pleistocene and holocene cirque glaciation in the enchantment lakes basin, north cascades, wa |
publisher |
Western CEDAR |
publishDate |
2004 |
url |
https://cedar.wwu.edu/wwuet/850 https://cedar.wwu.edu/cgi/viewcontent.cgi?article=1873&context=wwuet |
long_lat |
ENVELOPE(167.450,167.450,-78.083,-78.083) ENVELOPE(-111.452,-111.452,58.917,58.917) |
geographic |
Heine High Rock |
geographic_facet |
Heine High Rock |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
WWU Graduate School Collection |
op_relation |
https://cedar.wwu.edu/wwuet/850 https://cedar.wwu.edu/cgi/viewcontent.cgi?article=1873&context=wwuet |
op_rights |
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission. |
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1766130830160166912 |