12.1: Geomorphology and General Overview of the Great Valley Province
- Page ID
- 21534
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Physiographic Properties and Characteristics of the Great Valley
California’s Great Valley, often referred to as the Central Valley, is a 644 kilometer-long (400 mile) structural depression that stretches from the Transverse Range just south of Bakersfield northward to the Cascade Range (Figure 11.1). The Valley averages a width of 80 km (50 miles), that when combined with its length, makes for an area that is approximately 52,000 km2 (20,000 square miles). This area has very little relief, making most of the Valley sit close to sea level.
Physiographically, the Great Valley can be divided into two large parts: the northern one-third is known as the Sacramento Valley and the southern two-thirds is known as the San Joaquin Valley. The San Joaquin Valley can be split further into the San Joaquin Basin and the Tulare Basin. The San Joaquin and Sacramento Valleys meet in the Delta area where the combined discharge of the Sacramento and San Joaquin Rivers flows through the Great Valley's one natural outlet, the Carquinez Strait, on its way to San Francisco Bay and the Pacific Ocean. Just east of the Delta, several streams issue from the Sierra Nevada into the valley and flow to the Delta in an area referred to as the Eastside Streams.
The San Joaquin Valley is a Mediterranean environment with long, hot, and dry summers and wet winters. It lies north of the Transverse Range and south of the Sacramento Valley. The San Joaquin Valley produces close to 13% of the United States’ agricultural products which include grapes, raisins, cotton, almonds, citrus, and a plethora of vegetables. Each of these crops are water intensive, so pumping groundwater in the Great Valley for crop production is not uncommon.
The Great Valley is a large structural trough filled with sediments of Jurassic to Holocene age, as much as 20 km (12 miles) deep in the San Joaquin Valley, and as much as 9.6 km (6 miles) deep in the Sacramento Valley.
Sedimentary deposits filling the Valley vary somewhat depending on location. For example, the valley fill in the Sacramento Valley is predominantly fine-grained volcanic-derived sediments, although relatively coarse-grained deposits do occur along the river channels and the alluvial fans emanating from the Cascade Range and the northern Sierra Nevada.
In the San Joaquin valley, coarse grained sediments are more widespread, especially on the eastern side, and also occur along the major rivers; fine-grained sediments are associated with the largest amount of subsidence attributed to groundwater withdrawals recorded in the valley. Throughout this region, valley fill is capped by surface sediments are Pleistocene alluvium that are derived from the Sierra Nevada and the Temblor Range. These sediments were deposited on floodplains and low topography associated with river runoff and periodic flooding.
As is outlined in Chapter 17, three major watersheds exist within the Great Valley: the Sacramento River Basin, the San Joaquin River Basin, and the Tulare Lake Basin. The only drainage from the province is into the San Francisco Bay.
References
- California Department of Food and Agriculture (2010). California Agriculture Statistical Report 2008-2009.
- California Department of Conservation & Division of Oil, Gas, and Geothermal Resources. (1983). California Oil & Gas Fields: Northern California (TR10 ed., Vol. 3).
- California Department of Conservation & Division of Oil, Gas, and Geothermal Resources. (1991). California Oil & Gas Fields: Southern, Central coastal, and Offshore Californi (TR12 ed., Vol. 2).