This is a multilayer package combining these datasets:
Contours of Corcoran Clay Thickness
This digital dataset defines the extent, depth and thickness of the Corcoran Clay Member
of the Tulare Formation. The complex hydrologic system of the Central
Valley is simulated using the USGS numerical modeling code MODFLOW-FMP
(Schmid and others, 2006b). This simulation is referred to here as the
Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing
MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow,
irrigated agriculture, land subsidence, and other key processes in the
Central Valley on a monthly basis from 1961-2003. Numerous lenses of
fine-grained sediments are distributed throughout the southern Central
Valley (San Joaquin Valley) and generally constitute more than 50
percent of the total thickness of the valley fill. Generally, these
lenses are discontinuous and not vertically extensive or laterally
continuous. However, the Corcoran Clay is a low-permeability, areally
extensive, lacustrine deposit (Johnson and others, 1968) as much as
200-ft thick (Davis and others, 1959; Page, 1986). This continuous clay
divides the groundwater-flow system of the western San Joaquin Valley
into an upper semi-confined zone and a lower confined zone (Williamson
and others, 1989; Belitz and Heimes, 1990; Burow and others, 2004). The
extent and distribution of the Corcoran Clay was defined for use in the
CVHM because the unit is one of the few deposits in the Valley that can
be regionally mapped. The CVHM is the most recent regional-scale model
of the Central Valley developed by the U.S. Geological Survey (USGS).
More
information: https://catalog.data.gov/dataset/contours-of-corcoran-clay-depth-in-feet-from-page-1986-for-the-central-valley-hydrologic-model-