Masters Thesis

Glaciogenic, Geomorphic, and Insolation effects during MIS 2 on The Lacustrine Sediment Flux of Tulare Lake, California

Ever since the MIS 2 glacial maximum, Tulare Lake, CA, has been the terminus of four of the largest rivers from the southern Sierra Nevada Mountains and hydrologic modeling has shown that its surface elevation is a good gauge of Sierran stream discharge. Here we extend the relative paleolake-level record of Tulare Lake from the TL05-4 cores back to ~26 cal ka BP. Proxy data from these cores include magnetic susceptibility, grain size, total inorganic and organic carbon, and carbon-nitrogen ratios. To some extent, these data covary and based on comparisons of the Holocene part of this record with earlier trench sample-based lake-level records, they reflect relative lake level. The earliest part of the record shows that Tulare Lake experienced a sharp increase in lake level, possibly associated with the Dansgaard-Oeschger Event 2 or an increase in spill over elevation caused during periods of glacial advance. Evidenced by the gradually decreasing clay content, lake-level gradually decreased during the Tioga Glaciation (25-15 cal ka BP). This may have been caused by decreased summer precipitation and winter precipitation that was sequestered in the snowpack. During the late Tioga Glaciation, large amounts of runoff from the melting glaciers and addition of water from the Kings River filled the lake and significantly increase the sill height of the fan dam (18.6-15 cal ka BP) to more or less present elevations. After this, Tulare Lake stabilized and varied in conjunction primarily due to changes in sea surface temperatures. Correlations can be drawn between the new results shown here, to insolation, and to changing lake conditions of other lakes within California. This argues that the entire region is sensitive to insolation.

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