PLUVIAL LAKE DEPOSITS OF DEEP SPRINGS VALLEY, CALIFORNIA

Deep Springs Valley, located 35 km east of Bishop, California, is known for its terminal saline playa (elev. 1499 m). Deep Springs Valley has a relatively small drainage basin with streams emanating only from the White Mountains to the northwest at elevations as high as 4344 m. Observations and mapping from as early as 1928 found evidence of Quaternary stratified and fossiliferous pluvial lake deposits in Deep Springs Valley. The mapped elevation of the pluvial lake deposits (1646 m) is the same as the Soldier Pass wind gap (1648 m) between Deep Springs and Eureka Valleys. This observation led to the hypothesis that the pluvial Deep Springs Lake once flowed into Eureka Valley.

The objective of this study is to provide a more extensive description of the putative Deep Springs Lake deposits. As an isolated basin of limited areal extent, lake deposits in Deep Springs Valley would record past climate of the immediate area, which may be advantageous when comparing against climate records from the adjoining Owens Valley and nearby Death Valley.

We examined Deep Springs Lake deposits mapped in 1966 located northeast of a small hill called “The Elephant”. The deposits consisted of alternating beds of fine-grained, finely bedded, poorly cemented, fossiliferous sand to clayey sand and fine-to-medium-grained, coarse-bedded sand. Fossil freshwater gastropods Lymnaidae Stagnicola and Planorboidea Gyraulus were collected from the upper clayey sands. Ostracodes from the same upper clayey sand are dominated by Limnocythere ceriotuberosa and Fabaeformiscandona cf. caudata, which are found in freshwater to mildly saline environments. Fossils were not found elsewhere.

The gastropods, L. ceriotuberosa and F. cf. caudata are all consistent with a fresh to mildly saline lake depositional setting, rather than a spring or groundwater discharge environment. We interpret these data to indicate that Deep Springs Valley contained a freshwater lake that reached 1646 m and, based on the maximum elevation of Soldier Pass, flowed into Eureka Valley during a cooler, wetter climate. Samples of gastropod shell submitted for radiocarbon dating are ongoing; this will generate an absolute date of when water was present at those depths. Financial support for this project was provided by the Louis Strokes Alliance for Minority Participation.