13.10: Chapter Summary
- Page ID
- 24981
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)13.2: Physiographic Features of the Mojave & Colorado Desert Provinces
- The Mojave and Colorado Desert provinces are arid environments in the southeastern part of California.
- The relief in this area is more subdued than that of the Basin and Range province to the north, but geologic features are similar.
13.3: Geologic Overview and Evolution of the Mojave and Colorado Desert Provinces
- Rocks range in age from Late Proterozoic to Late Cenozoic in age are exposed in uplifted mountain ranges are as old as 2.5 Ga.
- Paleozoic rocks exposed in uplifted ranges consist of sediments deposited in a passive margin setting and have many marine fossils.
- Mesozoic rocks in the region are mostly granitic and metamorphic, associated with changing plate boundaries.
- Cenozoic units are typically found in down-dropped basins and contain evidence of dramatic changes in climate and tectonic setting over the past 30 million years.
13.4: Creating the Desert Environment
- The Mojave and Colorado Desert provinces are arid due to their position in the high pressure atmospheric belt associated with the meeting of the Prevailing Westerlies and the Northeast trade winds.
- These regions also occupy the rain shadow of the Sierra Nevada, Transverse ranges and Peninsular ranges.
- Weathering is dominated by physical processes here.
13.5: Wind Driven Sediment Transport
- Wind and water are the dominant modes of sediment transport in this region.
- Dune fields are established when wind is blocked and sediment is dropped.
- Blowing sand is abrasive and can sculpt ventifacts.
13.6: Sand Dunes and Dune Fields
- There are several large dune areas in the Mojave and Colorado Desert region. Such sand dunes and dune fields develop when there is adequate sediment supply and a way for sediment that is deposited to be stabilized.
13.7: Erosional Desert Landforms
- Inselbergs are remnants of old mountains that are surrounded by their own erosional debris.
- Pediments are flattened or low angle surfaces of bedrock with very little alluvium.
- Bedrock often exhibits spheroidal weathering as a result of chemical weathering.
- Desert pavement develops as light, small sediment is blown away from larger particles.
13.8: Water in the Desert
- Although deserts are dry environments, water in the form of flash floods can be an effective modifier of the landscape.
- The Mojave River is today an ephemeral stream which flows underwater for part of its stretch.
- Many dry lakes in this region were once connected in a larger system of lakes.
- The Salton Sea is a remnant of a flood event in which the Colorado river spilled its banks.
13.9: Geologic Resources in the Desert Provinces
- Evaporites are important resources in this region, forming in dry lakes.
- Strategically important resources, such as lithium, form in these environments associated with the Salton Sea Brine pools.
- Rare Earth elements are mined at Mountain Pass in eastern California.
13.10: Geologic Hazards
- Seismic hazard in this area is present due to the proximity of the San Andreas fault and the transition to the spreading center in the Gulf of Mexico.
- Flooding is a seasonal hazard here due to monsoonal storms.