Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska
This research examines moraine and lacustrine records of glacier fluctuations, in combination with palynological records of vegetation change, from the previously unstudied northwestern Ahklun Mountains in southwestern Alaska. Moraine mapping reveals that ice-cap outlet glaciers in the study area ex...
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ftutahsudc:oai:digitalcommons.usu.edu:etd-6295 2023-08-27T04:09:33+02:00 Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska Axford, Yarrow L. 2000-05-01T07:00:00Z application/pdf https://digitalcommons.usu.edu/etd/5245 https://doi.org/10.26076/2dd9-7ffd https://digitalcommons.usu.edu/context/etd/article/6295/viewcontent/2000_Axford_Yarrow.pdf unknown DigitalCommons@USU https://digitalcommons.usu.edu/etd/5245 doi:10.26076/2dd9-7ffd https://digitalcommons.usu.edu/context/etd/article/6295/viewcontent/2000_Axford_Yarrow.pdf Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. All Graduate Theses and Dissertations late quatrenary glacier fluctuations vegetation change northwestern ahklun mountains southwestern alaska Geology text 2000 ftutahsudc https://doi.org/10.26076/2dd9-7ffd 2023-08-10T17:37:11Z This research examines moraine and lacustrine records of glacier fluctuations, in combination with palynological records of vegetation change, from the previously unstudied northwestern Ahklun Mountains in southwestern Alaska. Moraine mapping reveals that ice-cap outlet glaciers in the study area extended ca. 60 km from the center of the Ahklun Mountians ice dome during the early Wisconsin (sensu lato), and ca. 40 km during the late Wisconsin. Correlations with well-studied moraines in the southern Ahklun Mountains indicate an asymmetry of glaciation over the range, with ice-cap outlet glaciers more extensive to the south. This asymmetry was more striking during the early Wisconsin (s.l.) than during the late Wisconsin. Alpine glaciers have repeatedly advanced from cirques within the study area. Because these alpine glaciers were confluent or sub-confluent with outlet glaciers during the late Wisconsin maximum, the alpine-glacier moraine record is relatively young. Lacustrine sedimentology from Little Swift Lake records significant retreat of alpine glaciers ca 12.8 ka (coeval with the onset of the North Atlantic Younger Dryas). Moraines upvalley of the lake suggests a minor glacier (or rock glacier) advance occurred ca 5.5 ka. Lacustrine records of vegetation from Little Swift Lake extend back to ca. 13.4 ka. Most vegetation changes resulted from the post-glacial spread of trees and shrubs, including Betula, Alnus, and Picea, to their modern ranges. However, pollen assemblages and other paleoclimate proxies suggest some major changes in late-glacial and Holocene climate. Major vegetation change, most notably the dramatic expansion of Poaceae, occurred ca. 100 yr after the 12.8-ka glacier retreat and persisted for more than 2 ka. The inferred reversal to dry (and possibly cool) climate was followed by a period of exceptionally productive mesic conditions during the early Holocene, ca. 11 to 9 ka. The pattern of latest-Quaternary climate changes documented in this study may be evidence that, as previous workers ... Text glacier glaciers Ice cap North Atlantic Alaska Utah State University: DigitalCommons@USU |
institution |
Open Polar |
collection |
Utah State University: DigitalCommons@USU |
op_collection_id |
ftutahsudc |
language |
unknown |
topic |
late quatrenary glacier fluctuations vegetation change northwestern ahklun mountains southwestern alaska Geology |
spellingShingle |
late quatrenary glacier fluctuations vegetation change northwestern ahklun mountains southwestern alaska Geology Axford, Yarrow L. Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska |
topic_facet |
late quatrenary glacier fluctuations vegetation change northwestern ahklun mountains southwestern alaska Geology |
description |
This research examines moraine and lacustrine records of glacier fluctuations, in combination with palynological records of vegetation change, from the previously unstudied northwestern Ahklun Mountains in southwestern Alaska. Moraine mapping reveals that ice-cap outlet glaciers in the study area extended ca. 60 km from the center of the Ahklun Mountians ice dome during the early Wisconsin (sensu lato), and ca. 40 km during the late Wisconsin. Correlations with well-studied moraines in the southern Ahklun Mountains indicate an asymmetry of glaciation over the range, with ice-cap outlet glaciers more extensive to the south. This asymmetry was more striking during the early Wisconsin (s.l.) than during the late Wisconsin. Alpine glaciers have repeatedly advanced from cirques within the study area. Because these alpine glaciers were confluent or sub-confluent with outlet glaciers during the late Wisconsin maximum, the alpine-glacier moraine record is relatively young. Lacustrine sedimentology from Little Swift Lake records significant retreat of alpine glaciers ca 12.8 ka (coeval with the onset of the North Atlantic Younger Dryas). Moraines upvalley of the lake suggests a minor glacier (or rock glacier) advance occurred ca 5.5 ka. Lacustrine records of vegetation from Little Swift Lake extend back to ca. 13.4 ka. Most vegetation changes resulted from the post-glacial spread of trees and shrubs, including Betula, Alnus, and Picea, to their modern ranges. However, pollen assemblages and other paleoclimate proxies suggest some major changes in late-glacial and Holocene climate. Major vegetation change, most notably the dramatic expansion of Poaceae, occurred ca. 100 yr after the 12.8-ka glacier retreat and persisted for more than 2 ka. The inferred reversal to dry (and possibly cool) climate was followed by a period of exceptionally productive mesic conditions during the early Holocene, ca. 11 to 9 ka. The pattern of latest-Quaternary climate changes documented in this study may be evidence that, as previous workers ... |
format |
Text |
author |
Axford, Yarrow L. |
author_facet |
Axford, Yarrow L. |
author_sort |
Axford, Yarrow L. |
title |
Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska |
title_short |
Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska |
title_full |
Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska |
title_fullStr |
Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska |
title_full_unstemmed |
Late Quaternary Glacier Fluctuations and Vegetation Change in the Northwestern Ahklun Mountains, Southwestern Alaska |
title_sort |
late quaternary glacier fluctuations and vegetation change in the northwestern ahklun mountains, southwestern alaska |
publisher |
DigitalCommons@USU |
publishDate |
2000 |
url |
https://digitalcommons.usu.edu/etd/5245 https://doi.org/10.26076/2dd9-7ffd https://digitalcommons.usu.edu/context/etd/article/6295/viewcontent/2000_Axford_Yarrow.pdf |
genre |
glacier glaciers Ice cap North Atlantic Alaska |
genre_facet |
glacier glaciers Ice cap North Atlantic Alaska |
op_source |
All Graduate Theses and Dissertations |
op_relation |
https://digitalcommons.usu.edu/etd/5245 doi:10.26076/2dd9-7ffd https://digitalcommons.usu.edu/context/etd/article/6295/viewcontent/2000_Axford_Yarrow.pdf |
op_rights |
Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
op_doi |
https://doi.org/10.26076/2dd9-7ffd |
_version_ |
1775351009135034368 |