Late Holocene sedimentary environments and lake-level fluctuations at Walker Lake, Nevada, USA

Walker Lake is a terminal lake located at the end of the Walker River in western Nevada. Lake-level lowering of approximately 50 m during the past 100 yr has led to deep incision by the Walker River into the former lake bed. This incision has exposed a sedimentary record of lake-level fluctuations spanning at least the past 4000 yr. Fourteen new radiocarbon dates on plant material collected from diverse sedimentary environments, including fluvial, deltaic, beach, and offshore settings, have led to the refinement of the late Holocene lake-level curve for this basin. This new curve documents at least four highstands that have occurred since ca. 3500 cal yr B.P. between elevations of 1245 and 1255 m. The lake has also experienced several lowstands during this same period. Comparison of this outcrop-based record to existing lake-level curves and to an oxygen isotope curve for the past 1200 yr reveals many similarities between the records, but also some differences. Therefore, research should be conducted to integrate outcrop studies, where absolute water depth and lake volume can be estimated, with isotopic or other types of proxies from cored sediments that may have higher temporal resolution. The extensive and nearly continuous outcrops along the lower Walker River also provide valuable information on the relationships between various sedimentary features and their formative water depths in clastic-dominated lacustrine systems. The paleo-water depth relationships deciphered here can be applied in other basins, where outcrops are typically more limited, to arrive at better-constrained lake-level records.