13: Mojave and Colorado Deserts
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Introduction to the Mojave and Colorado Deserts
Most of the southeastern portion of the state of California is a desert environment. In fact, the USGS estimates that approximately 30% of the state of California is a desert environment! In this chapter, you will learn about geologic processes and features that are associated with desert environments, with a special focus on the highlights of the Mojave and Colorado Desert Provinces.
The Mojave and Colorado Desert Provinces are situated in the southeastern portion of the state of California. They share a geographic border with the Basin and Range Province to the north, as well as many geologic qualities, so the reader is encouraged to review the Chapter on the Basin and Range along with their reading of this chapter (Figure \(\PageIndex{1}\)). In addition to offering unique landscapes and an opportunity to explore vast remote desert environments, these desert provinces are a source of mineral wealth and are the weekend playgrounds of many residents of southern California.
By the end of this chapter, you should be able to:
- Locate the Mojave and Colorado Desert provinces of California on a map of the state.
- Explain how the Mojave and the Colorado Deserts are created by geographic features, latitude, and atmospheric circulation.
- Describe the primary bedrock geologic characteristics of the Mojave and Colorado Desert Provinces.
- Recall the general geologic evolution of the Mojave and Colorado Desert Provinces.
- Describe the dominant desert weathering and erosion processes and their products in the Mojave and Colorado Desert Provinces.
- Describe evidence for climate changes impacting the Mojave and Colorado Desert Provinces.
- Describe the mineral resources in California’s desert provinces.
- Assess the geologic hazards and risks associated with the Mojave and Colorado Desert Provinces.
- 13.1: Physiographic Features of the Mojave and Colorado Desert Provinces
- This page discusses the Mojave and Colorado Desert Provinces in southeastern California, highlighting their basin and range topography shaped by geological history and climatic changes. It notes the Mojave Desert's elevations, the Colorado Desert's inclusion of the Salton Sea, and key landmarks like national parks. Both deserts were designated as a UNESCO Biosphere Reserve in 1984, focusing on biodiversity conservation, sustainable development, and community involvement.
- 13.2: Geologic Overview and Evolution of the Mojave and Colorado Desert Provinces
- This page outlines the geological history of the Mojave and Colorado Desert Provinces, noting ancient rocks dating back billions of years, a transition from passive to active margins, and ongoing tectonic activity. It includes details on the Salton Trough and Red Rock Canyon State Park's fossil records, highlighting diverse ancient fauna and the formation of the Salton Sea due to geological processes.
- 13.3: Creating the Desert Environment
- This page discusses the characteristics of deserts like the Mojave and Colorado Provinces, highlighting their low precipitation, temperature fluctuations, and specific geographic features that affect weathering and erosion. It notes that rainfall, though rare, drives significant geological changes.
- 13.4: Wind Driven Sediment Transport
- This page discusses the important role of wind in sediment transport and erosion in desert landscapes. It highlights processes such as suspension, saltation, and creep, where sand movement aids erosion through abrasion, shaping rocks into ventifacts. It also explains how deflation creates desert pavement and notes the hazards of blowing dust on health and agriculture, while also mentioning its potential benefit in enhancing soil moisture retention.
- 13.5: Sand Dunes and Dune Fields
- This page discusses sand dunes, particularly focusing on the Algodones Dune Field in California and the Kelso Dunes in the Mojave Desert. It explains how wind shapes these dune fields and their internal features, like cross bedding. The Algodones Dunes exhibit a variety of dune types influenced by local wind patterns and sediment sources, while the Kelso Dunes are noted for their unique "booming" sands and the effects of climate on their formation.
- 13.6: Erosional Desert Land Forms
- This page explores the formation of alluvial fans and bajadas in desert landscapes, focusing on the Mojave Desert. It explains that alluvial fans are created by sediment deposits from streams exiting canyons, while bajadas result from the merging of adjacent fans. The erosion of mountains leaves behind inselbergs on pediment surfaces.
- 13.7: Water in the Desert
- This page discusses the vital role of water in desert landscapes, focusing on the Mojave Desert's hydrology, including the Mojave River and the Salton Sea. It highlights the effects of heavy rains, flash floods, and the interaction between geology and climate.
- 13.8: Geological Resources of the Desert Provinces
- This page describes the Mojave and Colorado Desert Provinces, highlighting their valuable evaporite deposits and mineral resources, including rare earth elements, lithium, gold, and copper. Searles Lake is noted for its borate minerals, while Lithium Valley is crucial for battery production. The Mountain Pass Mine is the U.S.'s only active rare earth mining facility.
- 13.9: Geologic Hazards of the Mojave and Colorado Desert Provinces
- This page discusses the seismic hazards in the Mojave and Colorado Desert Provinces of California, highlighting risks from earthquakes, dust storms, debris flows, and flash floods. Key geological features include the Eastern California Shear Zone and the San Andreas Fault, with significant earthquakes recorded in the Landers (1992) and Hector Mine (1999). The Brawley Seismic Zone also presents hazards, and monsoonal storms can exacerbate flooding and alter the landscape.
- 13.10: Chapter Summary
- A summary of the Mojave and Colorado Deserts chapter.
- 13.11: Detailed Figure Descriptions
- Descriptions of complex images within this chapter, as well as additional guidance for users who have difficulty seeing and interpreting images.
Thumbnail: "Mojave and Colorado Deserts Provinces" is licensed under CC BY-NC 4.0 by Allison Jones.