Persistent Link:
http://hdl.handle.net/10150/187709
Title:
LATE PLEISTOCENE AND HOLOCENE ENVIRONMENTS IN THE GREAT BASIN.
Author:
THOMPSON, ROBERT STEPHEN.
Issue Date:
1984
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Pollen and packrat midden data from the Great Basin indicate that the Pleistocene vegetation of the region was a combination of subalpine conifers on coarse substrates and steppe plants on finer valley bottom soils. While some of the modern dominants of the woodland zone were apparently absent from this region, other woodland and montane plants apparently persisted through the late Pleistocene. Some features of the Pleistocene environment, such as the large pluvial lakes, apparently disappeared by 12,000 yr B.P., while subalpine plants remained well below their modern elevational limits after 11,000 yr B.P. Limber pine and Rocky Mountain juniper apparently did not retreat from the lower mountain slopes until after 6500 yr B.P. Montane and woodland conifers, rare or absent in the region during the Wisconsin, dispersed across the region in the Middle Holocene. Other plants apparently did not reach their modern geographic limits until after 3000 yr B.P. The low elevational occurrences of subalpine species suggest that the late Pleistocene climate of the Great Basin was characterized by summer temperatures that were as much as 10°C cooler than those of today, and that there was some augmentation in the level of mean annual precipitation. The vegetational records provide no evidence of greater than modern levels of summer precipitation. While the persistence of montane plants at relatively low elevations implies cool or moist conditions through the Early Holocene, evidence from lacustrine systems suggests that there was a trend toward increasingly dry conditions during this period. The main period of migrations of woodland plants seems to slightly postdate the warmest and/or driest part of the Holocene, and these migrations may have been related to relatively high levels in summer temperatures, summer precipitation, and/or winter temperatures. Pollen data from a high elevation site, in conjunction with changes in water level in lower elevational lakes, suggest a return to cooler and/or moister conditions after 4000 yr B.P.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Geology, Stratigraphic -- Pleistocene.; Geology, Stratigraphic -- Holocene.; Paleobotany -- Great Basin -- Pleistocene.; Paleobotany -- Great Basin -- Holocene.; Paleoclimatology -- Great Basin -- Pleistocene.; Paleoclimatology -- Great Basin -- Holocene.; Great Basin.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleLATE PLEISTOCENE AND HOLOCENE ENVIRONMENTS IN THE GREAT BASIN.en_US
dc.creatorTHOMPSON, ROBERT STEPHEN.en_US
dc.contributor.authorTHOMPSON, ROBERT STEPHEN.en_US
dc.date.issued1984en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractPollen and packrat midden data from the Great Basin indicate that the Pleistocene vegetation of the region was a combination of subalpine conifers on coarse substrates and steppe plants on finer valley bottom soils. While some of the modern dominants of the woodland zone were apparently absent from this region, other woodland and montane plants apparently persisted through the late Pleistocene. Some features of the Pleistocene environment, such as the large pluvial lakes, apparently disappeared by 12,000 yr B.P., while subalpine plants remained well below their modern elevational limits after 11,000 yr B.P. Limber pine and Rocky Mountain juniper apparently did not retreat from the lower mountain slopes until after 6500 yr B.P. Montane and woodland conifers, rare or absent in the region during the Wisconsin, dispersed across the region in the Middle Holocene. Other plants apparently did not reach their modern geographic limits until after 3000 yr B.P. The low elevational occurrences of subalpine species suggest that the late Pleistocene climate of the Great Basin was characterized by summer temperatures that were as much as 10°C cooler than those of today, and that there was some augmentation in the level of mean annual precipitation. The vegetational records provide no evidence of greater than modern levels of summer precipitation. While the persistence of montane plants at relatively low elevations implies cool or moist conditions through the Early Holocene, evidence from lacustrine systems suggests that there was a trend toward increasingly dry conditions during this period. The main period of migrations of woodland plants seems to slightly postdate the warmest and/or driest part of the Holocene, and these migrations may have been related to relatively high levels in summer temperatures, summer precipitation, and/or winter temperatures. Pollen data from a high elevation site, in conjunction with changes in water level in lower elevational lakes, suggest a return to cooler and/or moister conditions after 4000 yr B.P.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectGeology, Stratigraphic -- Pleistocene.en_US
dc.subjectGeology, Stratigraphic -- Holocene.en_US
dc.subjectPaleobotany -- Great Basin -- Pleistocene.en_US
dc.subjectPaleobotany -- Great Basin -- Holocene.en_US
dc.subjectPaleoclimatology -- Great Basin -- Pleistocene.en_US
dc.subjectPaleoclimatology -- Great Basin -- Holocene.en_US
dc.subjectGreat Basin.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.committeememberMartin, Paul S.en_US
dc.contributor.committeememberDavis, Owen K.en_US
dc.contributor.committeememberFerguson, C. Wesleyen_US
dc.contributor.committeememberFritts, Harold C.en_US
dc.contributor.committeememberTurner, Raymond M.en_US
dc.identifier.proquest8415081en_US
dc.identifier.oclc691273227en_US
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