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Pollen zonation and proposed informal climatic units for Clear Lake, California, cores CL-73-4 and CL-73-7

David P. Adam
Pollen zonation and proposed informal climatic units for Clear Lake, California, cores CL-73-4 and CL-73-7 (in Late Quaternary climate, tectonism, and sedimentation in Clear Lake, Northern California Coast Ranges, John D. Sims (editor))
Special Paper - Geological Society of America (1988) 214: 63-80

Abstract

Clear Lake occupies a structural depression in the northern California Coast Ranges at an elevation of 404 meters. Eight sediment cores were taken from the lake in 1973 and the palynology of cores CL-73-4 and CL-73-7 are reported. The former is 115 meters long, and is interpreted to cover the entire last glacial cycle; the latter is 27.5 meters long and covers at least the last 40,000 radiocarbon years. The pollen records of both cores are dominated by three pollen types (oak, pine, and TCT (Taxodiaceae, Cupressaceae, and Taxaceae) that together account for between 75 and 99 percent of the pollen in each sample. The present pollen rain around Clear Lake is dominated by oak pollen. During the cooler parts of the last glacial cycle , oak pollen influx to the sediments of Clear Lake was largely or entirely replaced by coniferous pollen (mostly pine and TCT) in response to vertical migration of vegetation belts caused by climatic changes. Pollen data were reduced using a Q-mode factor analysis. Five factors were defined that account for more than 98 percent of the variance. Zoning of the pollen diagrams was accomplished using an iterative program. The 21 pollen zones of core CL-73-4 are used to propose a series of informal climatic units that include the time interval from the penultimate glaciation to the present. The major units proposed, from oldest to youngest, are: (1) Tsabal cryomer, (2) Konocti thermomer, (3) Pomo cryomer, and (4) Tuleyome thermomer (Holocene). The record in the sediments of algae with acid-resistant remains indicates that lake productivity was relatively high during warm intervals in the past, and that overall productivity increased as the lake became shallower and its thermal inertia decreased. The lake waters were probably transparent during the cooler parts of the last glacial cycle, but Clear Lake has probably not been as clear a lake during the Holocene. (See also W89-10137) (Author 's abstract)


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 214
Title: Pollen zonation and proposed informal climatic units for Clear Lake, California, cores CL-73-4 and CL-73-7
Title: Late Quaternary climate, tectonism, and sedimentation in Clear Lake, Northern California Coast Ranges
Author(s): Adam, David P.
Author(s): Sims, John D.editor
Affiliation: U. S. Geol. Surv., Menlo Park, CA, United States
Affiliation: U. S. Geol. Surv., Menlo Park, CA, United States
Pages: 63-80
Published: 1988
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 0-8137-2214-4
References: 26
Accession Number: 1988-068790
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, sketch map
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from USGS product, Selected Water Resources Abstracts, Reston, VA, United States
Update Code: 1988
Program Name: USGSOPNon-USGS publications with USGS authors
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