RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET.
A Map of northern North America is presented which shows isochrones of the outer limit of the Laurentide ice sheet from about 13,000 years ago until the present. The data points are radiocarbon dates of moraines, basal peat, and lacustrine deposits which represent the dates of deglaciation. The chro...
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ftdtic:AD0664816 2023-05-15T15:00:41+02:00 RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. Bryson,Reid A. Wendland,Wayne M. WISCONSIN UNIV MADISON DEPT OF METEOROLOGY 1967-12 text/html http://www.dtic.mil/docs/citations/AD0664816 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0664816 en eng http://www.dtic.mil/docs/citations/AD0664816 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Geology Geochemistry and Mineralogy Snow Ice and Permafrost (*GEOLOGIC AGE DETERMINATION ICE) (*GLACIERS NORTH AMERICA) DEPOSITS PERIODIC VARIATIONS CLOUD COVER ENERGY HEAT TRANSFER GREAT LAKES HISTORY ARCTIC REGIONS ARCTIC OCEAN ISLANDS MAPS MASS TRANSFER RADIOCARBON DATING Text 1967 ftdtic 2016-02-18T20:47:00Z A Map of northern North America is presented which shows isochrones of the outer limit of the Laurentide ice sheet from about 13,000 years ago until the present. The data points are radiocarbon dates of moraines, basal peat, and lacustrine deposits which represent the dates of deglaciation. The chronology of the ice sheet shows that the ice front retreated northward from the Great Lakes to south of James Bay by about 8,000 years ago. By about 7,500 yrs BP, the continental ice sheet was split by an open Hudson Bay, with one center of ice over northern Keewatin and Baffin Island, and another about 400 km south of Ungava. By 7,000 yrs BP, the ice over Baffin Island had separated from the mass of ice to the west. The Baffin Island ice remained after that time, and apparently is found today as the Barnes Ice Cap and the Penny Glacier. The ice retreated faster over the Prairie Provinces than over the Labrador-Quebec area, suggesting that snowfall and/or cloud cover inhibited the retreat in the more maritime area. A glacial energy balance is presented which compares a glacial net radiation regime to that of a non-glacial time. The effect of variations in mean cloud cover and snowfall upon the ablation rate are investigated. It is suggested that cloud cover is the important determining factor for glacial net budget at lower latitudes, and that snowfall is more important at higher latitudes. (Author) Text Arctic Arctic Ocean Baffin Island Baffin Barnes Ice Cap Hudson Bay Ice Ice cap Ice Sheet Keewatin permafrost James Bay Defense Technical Information Center: DTIC Technical Reports database Arctic Arctic Ocean Hudson Bay Baffin Island Hudson Barnes Ice Cap ENVELOPE(-73.498,-73.498,70.001,70.001) |
institution |
Open Polar |
collection |
Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Geology Geochemistry and Mineralogy Snow Ice and Permafrost (*GEOLOGIC AGE DETERMINATION ICE) (*GLACIERS NORTH AMERICA) DEPOSITS PERIODIC VARIATIONS CLOUD COVER ENERGY HEAT TRANSFER GREAT LAKES HISTORY ARCTIC REGIONS ARCTIC OCEAN ISLANDS MAPS MASS TRANSFER RADIOCARBON DATING |
spellingShingle |
Geology Geochemistry and Mineralogy Snow Ice and Permafrost (*GEOLOGIC AGE DETERMINATION ICE) (*GLACIERS NORTH AMERICA) DEPOSITS PERIODIC VARIATIONS CLOUD COVER ENERGY HEAT TRANSFER GREAT LAKES HISTORY ARCTIC REGIONS ARCTIC OCEAN ISLANDS MAPS MASS TRANSFER RADIOCARBON DATING Bryson,Reid A. Wendland,Wayne M. RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. |
topic_facet |
Geology Geochemistry and Mineralogy Snow Ice and Permafrost (*GEOLOGIC AGE DETERMINATION ICE) (*GLACIERS NORTH AMERICA) DEPOSITS PERIODIC VARIATIONS CLOUD COVER ENERGY HEAT TRANSFER GREAT LAKES HISTORY ARCTIC REGIONS ARCTIC OCEAN ISLANDS MAPS MASS TRANSFER RADIOCARBON DATING |
description |
A Map of northern North America is presented which shows isochrones of the outer limit of the Laurentide ice sheet from about 13,000 years ago until the present. The data points are radiocarbon dates of moraines, basal peat, and lacustrine deposits which represent the dates of deglaciation. The chronology of the ice sheet shows that the ice front retreated northward from the Great Lakes to south of James Bay by about 8,000 years ago. By about 7,500 yrs BP, the continental ice sheet was split by an open Hudson Bay, with one center of ice over northern Keewatin and Baffin Island, and another about 400 km south of Ungava. By 7,000 yrs BP, the ice over Baffin Island had separated from the mass of ice to the west. The Baffin Island ice remained after that time, and apparently is found today as the Barnes Ice Cap and the Penny Glacier. The ice retreated faster over the Prairie Provinces than over the Labrador-Quebec area, suggesting that snowfall and/or cloud cover inhibited the retreat in the more maritime area. A glacial energy balance is presented which compares a glacial net radiation regime to that of a non-glacial time. The effect of variations in mean cloud cover and snowfall upon the ablation rate are investigated. It is suggested that cloud cover is the important determining factor for glacial net budget at lower latitudes, and that snowfall is more important at higher latitudes. (Author) |
author2 |
WISCONSIN UNIV MADISON DEPT OF METEOROLOGY |
format |
Text |
author |
Bryson,Reid A. Wendland,Wayne M. |
author_facet |
Bryson,Reid A. Wendland,Wayne M. |
author_sort |
Bryson,Reid A. |
title |
RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. |
title_short |
RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. |
title_full |
RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. |
title_fullStr |
RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. |
title_full_unstemmed |
RADIOCARBON ISOCHRONES OF THE RETREAT OF THE LAURENTIDE ICE SHEET. |
title_sort |
radiocarbon isochrones of the retreat of the laurentide ice sheet. |
publishDate |
1967 |
url |
http://www.dtic.mil/docs/citations/AD0664816 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0664816 |
long_lat |
ENVELOPE(-73.498,-73.498,70.001,70.001) |
geographic |
Arctic Arctic Ocean Hudson Bay Baffin Island Hudson Barnes Ice Cap |
geographic_facet |
Arctic Arctic Ocean Hudson Bay Baffin Island Hudson Barnes Ice Cap |
genre |
Arctic Arctic Ocean Baffin Island Baffin Barnes Ice Cap Hudson Bay Ice Ice cap Ice Sheet Keewatin permafrost James Bay |
genre_facet |
Arctic Arctic Ocean Baffin Island Baffin Barnes Ice Cap Hudson Bay Ice Ice cap Ice Sheet Keewatin permafrost James Bay |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/AD0664816 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766332771060416512 |