Revised 12/2002

NOTE

36

NOTE

36CALIFORNIA

GEOMORPHIC PROVINCES

CALIFORNIA

GEOMORPHIC PROVINCES

©California Department of Conservation, California Geological Survey, 2002. Reproduction of this CGS Note for classroom or public education purposesis encouraged and does not require written permission. However, please cite California Geological Survey as source.The Department of Conservation makes no warranties as to the suitability of this product for any particular purpose.

CALIFORNIA GEOLOGICAL SURVEY

California’s Geomorphic Provinces

California's geomorphic provinces are naturallydefined geologic regions that display a distinctlandscape or landform. Earth scientists recognizeeleven provinces in California. Each regiondisplays unique, defining features based ongeology, faults, topographic relief and climate.

These geomorphic provinces are remarkablydiverse. They provide spectacular vistas andunique opportunities to learn about earth'sgeologic processes and history.

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CALIFORNIA GEOMORPH

SIERRA NEVADA. The Sierra is a tiltedfault block nearly 400 miles long. Its eastface is a high, rugged multiple scarp,contrasting with the gentle western slope(about 2°) that disappears undersediments of the Great Valley. Deep rivercanyons are cut into the western slope.Their upper courses, especially inmassive granites of the higher Sierra, aremodified by glacial sculpturing, formingsuch scenic features as Yosemite Valley.The high crest culminates in Mt. Whitneywith an elevation of 14,495 feet abovesea level near the eastern scarp. Themetamorphic bedrock contains gold-bearing veins in the northwest trendingMother Lode. The northern Sierraboundary is marked where bedrockdisappears under the Cenozoic volcaniccover of the Cascade Range.

MODOC PLATEAU. The Modoc Plateauis a volcanic table land (elevation 4,000-6,000 feet above sea level) consisting of athick accumulation of lava flows and tuffbeds along with many small volcaniccones. Occasional lakes, marshes, andsluggishly flowing streams meanderacross the plateau. The plateau is cut bymany north-south faults. The province isbound indefinitely by the Cascade Rangeon the west and the Basin and Range onthe east and south.

MODOCPLATEAU

KLAMATH MOUNTAINS. The KlamathMountains have rugged topography withprominent peaks and ridges reaching6,000-8,000 feet above sea level. In thewestern Klamath, an irregular drainage isincised into an uplifted plateau called theKlamath peneplain. The uplift has leftsuccessive benches with gold-bearinggravels on the sides of the canyons. TheKlamath River follows a circuitouscourse from the Cascade Range throughthe Klamath Mountains. The province isconsidered to be a northern extension ofthe Sierra Nevada.

KLAMATHMOUNTAINS

GREAT VALLEY. The Great Valley isan alluvial plain about 50 miles wideand 400 miles long in the central part ofCalifornia. Its northern part is theSacramento Valley, drained by theSacramento River and its southern partis the San Joaquin Valley drained by theSan Joaquin River. The Great Valley is atrough in which sediments have beendeposited almost continuously since theJurassic (about 160 million years ago).Great oil fields have been found insouthernmost San Joaquin Valley andalong anticlinal uplifts on its southwest-ern margin. In the Sacramento Valley,the Sutter Buttes, the remnants of anisolated Pliocene volcano, rise above thevalley floor .

GREATVALLEY

CASCADE RANGE. The CascadeRange, a chain of volcanic cones, extendsthrough Washington and Oregon intoCalifornia. It is dominated by Mt. Shasta,a glacier-mantled volcanic cone, rising14,162 feet above sea level. The southerntermination is Lassen Peak, which lasterupted in the early 1900s. The CascadeRange is transected by deep canyons ofthe Pit River. The river flows through therange between these two major volcaniccones, after winding across interiorModoc Plateau on its way to theSacramento River.

CASCADERANGE

SIERRANEVADA

TRANSVERSERANGES

TRANSVERSE RANGES. TheTransverse Ranges are an east-westtrending series of steep mountainranges and valleys. The east-weststructure of the Transverse Ranges isoblique to the normal northwesttrend of coastal California, hencethe name "Transverse." Theprovince extends offshore to includeSan Miguel, Santa Rosa, and SantaCruz islands. Its eastern extension,the San Bernardino Mountains, hasbeen displaced to the south alongthe San Andreas Fault. Intensenorth-south compression issqueezing the Transverse Ranges.As a result, this is one of the mostrapidly rising regions on earth.Great thicknesses of Cenozoicpetroleum-rich sedimentary rockshave been folded and faulted,making this one of the important oil-producing areas in the United States.

ORPHIC PROVINCES

PENINSULAR RANGES. A series ofranges is separated by northwesttrending valleys, subparallel to faultsbranching from the San Andreas Fault.The trend of topography is similar to theCoast Ranges, but the geology is morelike the Sierra Nevada, with graniticrock intruding the older metamorphicrocks. The Peninsular Ranges extendinto lower California and are bound onthe east by the Colorado Desert. TheLos Angeles Basin and the island group(Santa Catalina, Santa Barbara, and thedistinctly terraced San Clemente andSan Nicolas islands), together with thesurrounding continental shelf (cut bydeep submarine fault troughs), areincluded in this province.

COLORADO DESERT. A low-lyingbarren desert basin, about 245 feet belowsea level in part, is dominated by theSalton Sea. The province is a depressedblock between active branches ofalluvium-covered San Andreas Fault withthe southern extension of the MojaveDesert on the east. It is characterized bythe ancient beach lines and silt depositsof extinct Lake Cahuilla.

MOJAVE DESERT. The Mojave is abroad interior region of isolated mountainranges separated by expanses of desertplains. It has an interior enclosed drainageand many playas. There are two importantfault trends that control topography aprominent NW-SE trend and a secondaryeast-west trend (apparent alignment withTransverse Ranges is significant). TheMojave province is wedged in a sharpangle between the Garlock Fault (southernboundary Sierra Nevada) and the SanAndreas Fault, where it bends east fromits northwest trend. The northernboundary of the Mojave is separated fromthe prominent Basin and Range by theeastern extension of the Garlock Fault.

BASIN and RANGE. The Basin andRange is the westernmost part of theGreat Basin. The province is character-ized by interior drainage with lakes andplayas, and the typical horst and grabenstructure (subparallel, fault-boundedranges separated by downdroppedbasins). Death Valley, the lowest area inthe United States (280 feet below sealevel at Badwater), is one of thesegrabens. Another graben, Owens Valley,lies between the bold eastern fault scarpof the Sierra Nevada and Inyo Mountains.The northern Basin and Range Provinceincludes the Honey Lake Basin.

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PENINSULARRANGES

BASINANDRANGE

MOJAVEDESERT

COLORADODESERT

COAST RANGES. The Coast Ranges arenorthwest-trending mountain ranges(2,000 to 4,000, occasionally 6,000 feetelevation above sea level), and valleys.The ranges and valleys trend northwest,subparallel to the San Andreas Fault.Strata dip beneath alluvium of the GreatValley. To the west is the Pacific Ocean.The coastline is uplifted, terraced andwave-cut. The Coast Ranges arecomposed of thick Mesozoic andCenozoic sedimentary strata. Thenorthern and southern ranges areseparated by a depression containing theSan Francisco Bay. The northern CoastRanges are dominated by irregular,knobby, landslide-topography of theFranciscan Complex. The eastern borderis characterized by strike-ridges andvalleys in Upper Mesozoic strata. Inseveral areas, Franciscan rocks areoverlain by volcanic cones and flows ofthe Quien Sabe, Sonoma and Clear Lakevolcanic fields. The Coast Ranges aresubparallel to the active San AndreasFault. The San Andreas is more than 600miles long, extending from Pt. Arena tothe Gulf of California. West of the SanAndreas is the Salinian Block, a graniticcore extending from the southernextremity of the Coast Ranges to thenorth of the Farallon Islands.

COASTRANGES

NATURAL RESOURCES AGENCY JOHN LAIRD

SECRETARY FOR RESOURCES

Offices of the California Geological Survey

CGS Headquarters

801 K Street, MS 12-30 Sacramento, CA 95814-3532 (916) 445-1825

Southern California Regional Office

320West 4th Street, Suite 850 Los Angeles, CA 90013(213) 239-0878

Bay Area Regional Office 345 Middlefield Road, MS 520 Building 3, Room 3-251 Menlo Park, CA 94025 (650) 688-6327(650) 688-6329 FAX

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Based on the Geomorphic Map of California prepared by Olaf P. Jennings, 1938. Revisions of the text by D.L.Wagner, 2002.

STATE OF CALIFORNIAEDMUND G. BROWN JR.

GOVERNOR

DEPARTMENT OF CONSERVATION DAVID BUNNDIRECTOR

Selected Sierra Nevada Field Guides of the California Geological Survey

❍ SP109 Geologic Excursions in Northern California: San Francisco to the Sierra Nevada. 1991

❍ SP119 Geologic Field Trips in Northern California. 1999

❍ SP122 Field Guide to the Geology and Tectonics of the Northern Sierra Nevada. 2000

To order these or other California Geological Survey publications, call (916) 327-1850, or visit the CGS publications Web page at http://www.conservation.ca.gov/cgs/information/publications/index.htm.

www.conservation.ca.gov

If you are interested in learning more about the geomorphic provinces and geology of California,please visit the California Geotour (http://www.conservation.ca.gov/cgs/geotour). The CaliforniaGeotour is an index of linked Web pages of geologic field trip guides and related Web sites thatcontain geologic information, including photographs, maps, text and directions for local naturalfeatures throughout the state. The index is organized by California's geomorphic provinces.

Also visit the California Geological Survey's homepage at http://www.conservation.ca.gov/cgs.There you will find more information on the geology, resources and geologic hazards of California.