THE LAST 3000 YEARS OF CALIFORNIA HYDROLOGIC VARIABILITY: COMPARISON OF LATE HOLOCENE SEDIMENT PALEOCLIMATE RECORDS FROM THE WESTERN USA

We have recovered late Holocene paleoclimate records from six sediment sequences in the California region, which form a transect from NW Nevada to Southern California: Pyramid Lake (NV), Walker Lake (NV), Mono Lake (CA), Owens Lake (CA), Santa Cruz coast (CA), Lake Elsinore (CA). The cores are all C14 dated and correlated with paleomagnetic field secular variation. In this study, our goal is to compare multi-proxy evidence for centennial- to millennial-scale hydrologic (lake-level) variability among the records and look for regional patterns in that variability. Different records have different degrees of resolution or response, so distinctive patterns in some records are not expected to be visible in all records. We see clear evidence for a coherent pattern of centennial- to millennial-scale hydrologic variability in all of these records based on multiple proxies. We infer that the specific regional pattern of lake-level variability, which we have developed, is due largely to longterm, regionally-coherent rainfall variability. That longterm rainfall variability is not recorded in nearby tree-ring records due to limitations in longterm trend reconstruction in tree-ring studies. We also see evidence for ENSO to multi-decadal variability in several of the records, which is correlatable with tree-ring studies.