Smith Valley is a small valley located in west-central Nevada about 35 km southeast of the Carson Valleyin a region of the western United States commonly known as the Basin and Range. Like many valleys in the Basin and Range, Smith Valley exists because of the normal faulting in the region.
Normal faults are oriented so that the fault plane is nearly vertical and the sense of motion on these faults is shown in the diagram below. The Basin and Range gets its name from the parallel mountain ranges and valleys created mainly by motion on these normal faults.
These valleys can also form closed basins, meaning that while there is some inflow of water into the valley, there is no outflow. During the late Pleistocene, about 13,000 years ago, the climate of this region was such that the precipitation exceeded evaporation and large lakes known as pluvial lakes filled these valleys.
Smith Valley was once one such closed basin, but my Master’s research showed that sometime between approximately 80,000 and 13,000 years ago, the West Walker River developed through flowing drainage in the valley, creating an outlet for the water (Fig 5), so that the lake existing in the valley at ~80,000 years had mostly drained out by 13,000 years ago.
While my research focused on the Pleistocene lake sediments and shorelines in Smith Valley, there are many interesting things about the geologic history of the valley and surrounding area.
In this series of blog posts, I will focus on various geologic aspects of Smith Valley. I’m starting with the faults in the valley, and specifically the Smith Valley Fault Zone, which located at the base of the Pine Nut Mountains, on the western edge of the valley.
Some references:
Reheis, M.C., 1999a, Extent of Pleistocene Lakes in the western Great Basin: USGS Miscellaneous Field Studies Map MF-2323, U.S. Geological Survey, Denver, CO. https://pubs.usgs.gov/mf/1999/mf-2323/
