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Research about Clear Lake

Source-linked reports with geographic coverage including Clear Lake.

27 records · Page 2Linked to original sources
USGS1979

Pollen counts from core 7, Clear Lake, Lake County, California

The U. S. Geological Survey recovered eight sediment cores from beneath Clear Lake, Lake County, California, in 1973. The locations of the core sites are shown in fig. 1; lithologic descriptions of the cores, as well as radiographs, have been given by Sims and Rymer (1975a-g, 1976). A list of the procedures followed in sampling the cores and a list of the samples taken may be found in Beaver and others (1975); fish remains from two of the cores have been studied by Casteel and others (1975, 1977a,1977b). This report gives raw count data for 72 pollen samples from core 7, a 27.4-m long core from the southern or Highlands Arm of the lake (fig. 1). Pollen counts for core 4, a 115-m core from the main basin of the lake, are given in Adam (1979); that core spans the time interval between the end of the penultimate glacial period, about 130,000 years ago, and the present.

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USGS1979

Fish remains from core 8, Clear Lake, Lake County, California

A 21.2-m-long core taken in the northwest part of the Upper Arm or main body of Clear Lake, California, has yielded a continuous record of fish life in this part of the lake during approximately the last 24,500 years. This record provides data concerning faunal changes in the Upper Arm, and also permits reconstruction of fish sizes and growth rates based upon scale remains. Four tables are presented that provide data on sample numbers and their frequency of occurrence and identification of skeletal and scale remains, and the reconstructed lengths and weights of Tule perch ( Hysterocarpus traski Gibbons) based upon remains of the scales of this species. A fifth table presents the mean reconstructed standard lengths and mean ages in years B.P. for slugs 1 through 24, 0-18.3 m. These data provide a unique data base for examination of paleoecologic and paleoclimatic trends in the North Coast Range of California through the Holocene and late Pleistocene. The record augments similar paleoecologic and paleoclimatic trends reconstructed from Core 6 and 7, taken in the Highlands and Oaks Arms of Clear Lake, respectively.

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USGS1979

Chemical composition of water and gas from five nearshore subaqueous springs in Clear Lake, Northern California

In 1971 The Geysers-Clear Lake area was selected by the U.S. Geological Survey geothermal research program as a region for extensive investigation. Under this program thermal water samples were first collected in December, 1974 during a winter of normal rainfall; the last samples were collected in February, 1977 during a period of drought. The drought exposed many springs which normally are submerged by Clear Lake. The collection and analysis of these springs is reported in Thompson and others (this vol.).

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USGS1978

Mercury analysis of sediments from cores in Clear Lake, Lake County, California

Cores of late Quaternary sediments were collected from several sites in Clear Lake (fig. 1). Samples from two of these cores (fig. 2, 3) have been analyzed for their mercury content as part of a study on the time of emplacement of the mercury ore body at the nearby Sulphur Bank mine (fig. 1). The samples were analyzed in laboratories of the U.S. Geological Survey by the mercury vapor detector method (Vaughn and McCarthy, 1964; Vaughn, 1967). The analyses of core 6, except samples 332, 341, 343, 386, 406, and 462, were done by Mr. Kam Leong (Table 1); the remaining analyses were done by Mr. Allen Meier. Analyses of core 10 (table 2) were done by Mr. Meier. Meier reported interference by organic material in the samples he analyzed. Because the two sets of data are not in agreement, most of the samples submitted to Leong and Meier are being reanalyzed.

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USGS1976

Sampling procedures and catalogue of samples for eight boreholes at Clear Lake, Lake County, California

Clear Lake, California, is situated in an area which has been subject to crustal movement, earthquake-generated ground shaking, volcanic eruptions, and climatic fluctuations during late Quaternary time. The U.S. Geological Survey, in cooperation with Lake County, has undertaken a study of the seismic, volcanic, and environmental history recorded in the late Quaternary sediments beneath the floor of the lake (Sims, 1974). This study is based on continuous core samples measuring 12 cm or 15 cm in diameter that were obtained in August-November, 1973, from 8 boreholes measuring 14-113 m in length (Figure 1). Preliminary description of many of these samples and interpretation of ancient seismic events can be found in Sims and Rymer (1975). Over 2,000 multiple samples have been taken from these cores in order to study the environmental record preserved in the lacustrine sediments. Samples were taken for pollen, diatoms, cladocera, bulk mineralogy, fine size analysis, macrofossils, and water-content/organic carbon-content at designated depths. In addition, volcanic ash and radiocarbon samples were removed for correlation studies and age determinations. This report provides a description of the standard sampling procedures designed for sapropelic muds and peat-rich clays, a description of modified sampling procedures developed for sampling sands and coarser sediments, and a catalogue of samples from the Clear Lake cores. Table 2 outlines the steps followed for the standard sampling procedures.

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USGS1976

Preliminary description and interpretation of cores and radiographs from Clear Lake, Lake County, California: Core 3

Clear Lake, California is located in the California Coast Ranges about 120 km north of San Francisco and is the largest freshwater lake wholly within California. The lake basin is tectonically controlled (Anderson, 1936; Brice, 1953; Sims and Rymer, 1974) and the area seismically active (Coffman and von Hake, 1973). Interest in this lake was stimulated by hypotheses developed from a study of sediments in Van Norman Reservoir after the 1971 San Fernando earthquake (Sims, 1973). During this study three zones of deformational structures were found in the 1 m-thick sequence of sediments exposed over about 2 km2 of the reservoir bottom. These zones were correlated with moderate earthquakes that shook the San Fernando area in 1930, 1952, and 1971. Results of this study, coupled with the experimental formation of deformational structures similar to those from Van Norman Reservoir, led to a search for similar structures in Pleistocene and Holocene lakes and lake sediments in other seismically active areas. Clear Lake, California was chosen specifically because of its location near the San Andreas fault and the San Francisco-Oakland urban complex, and the probability of obtaining an uninterrupted sediment record from the present into Pleistocene time. Eight 12 to 15 cm diameter continuous cores were taken from the lake sediments (fig. 1) as part of a study of earthquake induced structures in sediments and the tectonic framework of the Clear Lake basin. The eight cores range in length from 13.87 m to 115.21 m (Table 1).

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USGS1975

Preliminary description and interpretation of cores and radiographs from Clear Lake, Lake County, California: Core 7

Clear Lake, California is located in the California Coast Ranges about 120 km north of San Francisco and is the largest freshwater lake wholly within California. The lake basin is tectonically controlled (Anderson, 1936; Brice, 1953, Sims and Rymer, 1974) and the area seismically active (Coffman and von Hake, 1973). Interest in this lake was stimulated by hypotheses developed from a study of sediments in Van Norman Reservoir after the 1971 San Fernando earthquake (Sims, 1973). During this study three zones of deformational structures were found in the 1 m-thick sequence of sediments exposed over about 2 km 2 of the reservoir bottom. These zones were correlated with moderate earthquakes that shook the San Fernando area in 1930, 1952, and 1971. Results of this study, coupled with the experimental formation of deformational structures similar to those from Van Norman Reservoir, led to a search for similar structures in Pleistocene and Holocene lakes and lake sediments in other seismically active areas. Clear Lake, California was chosen specifically because of .:s location near the San Andreas fault and the San Francisco-Oakland urban complex, and the probability of obtaining an uninterrupted sediment record from the present into Pleistocene time. Eight 12 to 15 cm diameter continuous cores were taken from the lake sediments (fig. 1) as part of a study of earthquake induced structures in sediments and the tectonic framework of the Clear Lake basin. The eight cores range in length from 13.87 m to 133.09 m (Table 1).

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