soil survey of santa monica mountains national recreation ......mountains national recreation area,...

United StatesDepartment ofAgriculture

NaturalResourcesConservationService

In cooperation with Soil Survey ofSanta MonicaMountainsNationalRecreation Area,California

United StatesDepartment ofthe Interior,National ParkService

General Soil Map

The general soil map, which is a color map, shows the survey area divided into groupsof associated soils called general soil map units. This map is useful in planning the useand management of large areas.

To find information about your area of interest, locate that area on the map, identify thename of the map unit in the area on the color-coded map legend, then refer to thesection General Soil Map Units for a general description of the soils in your area.

Detailed Soil Maps

The detailed soil maps can be useful in planning the use and management of smallareas.

To find information about your area of interest,locate that area on the Index to MapSheets. Note the number of themap sheetand turnto thatsheet.

Locateyour areaof intereston themapsheet.Note themap unitsymbolsthat arein thatarea. Turnto theContents,whichlists themapunits by symbol and name and shows the page where each map unit is described.

The Contents shows which table has data on a specific land use for each detailed soilmap unit. Also see the Contents for sections of this publication that may address yourspecific needs.

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How To Use This Soil Survey

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National Cooperative Soil Survey

This soil survey is a publication of the National Cooperative Soil Survey, a joint effortof the United States Department of Agriculture and other Federal agencies, Stateagencies including the Agricultural Experiment Stations, and local agencies. The NaturalResources Conservation Service (formerly the Soil Conservation Service) hasleadership for the Federal part of the National Cooperative Soil Survey.

Major fieldwork for this soil survey was completed in 2001. Soil names anddescriptions were approved in 2001. Unless otherwise indicated, statements in thispublication refer to conditions in the survey area in 2001. This survey was madecooperatively by the Natural Resources Conservation Service and the United StatesDepartment of the Interior, National Park Service. The survey is part of the technicalassistance furnished to the Ventura County and Santa Monica Mountains ResourceConservation Districts.

Soil maps in this survey may be copied without permission. Enlargement of thesemaps, however, could cause misunderstanding of the detail of mapping. If enlarged,maps do not show the small areas of contrasting soils that could have been shown at alarger scale.

The most current soil information and interpretations for this survey area are availableeither through the Soil Data Mart or in the Field Office Technical Guide (FOTG) at thelocal field office of the Natural Resources Conservation Service. The Soil Data Mart isthe Natural Resources Conservation Service data storage site for the official soil surveyinformation. The FOTG is linked to the Soil Data Mart; therefore, the same information isavailable from both sources. Soil survey maps and tabular data can be accessedthrough the Soil Data Mart at http://soildatamart.nrcs.usda.gov. The official soil surveyinformation stored at the Soil Data Mart and this soil survey report are also availablethrough Web Soil Survey at http://soils.usda.gov/survey.

Nondiscrimination Statement

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programsand activities on the basis of race, color, national origin, age, disability, and whereapplicable, sex, marital status, familial status, parental status, religion, sexualorientation, genetic information, political beliefs, reprisal, or the fact that all or a part ofan individual’s income is derived from any public assistance program. (Not all prohibitedbases apply to all programs.) Persons with disabilities who require alternative means forcommunication of program information (Braille, large print, audiotape, etc.) shouldcontact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaintof discrimination, write to USDA, Director, Office of Civil Rights, 1400 IndependenceAvenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or(202) 720-6382 (TDD). USDA is an equal opportunity provider and employer.

Citation

The correct citation for this survey is as follows:

United States Department of Agriculture, Natural Resources Conservation Service.2006. Soil survey of Santa Monica Mountains National Recreation Area, California.Accessible online at: http://soils.usda.gov/survey/printed_surveys/.

Cover Caption

View of Castro Peak, showing an uplifted sandstone fin surrounded by Sumiwawasoils.

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Contents

How To Use This Soil Survey ....................................................................................... iContents ..................................................................................................................... iiiForeword .................................................................................................................... viiGeneral Nature of the Survey Area ............................................................................. 1

History and Development ........................................................................................ 1Physiography, Relief, and Drainage ......................................................................... 3Water Supply ........................................................................................................... 4Agriculture................................................................................................................ 5Altered Soils ............................................................................................................. 5Fire History .............................................................................................................. 6Soil Slippage ............................................................................................................ 6Climate ..................................................................................................................... 7

How This Survey Was Made ........................................................................................ 9Survey Procedures ................................................................................................ 10

General Soil Map Units ............................................................................................ 131. Sulfic Fluvaquents-Camarillo-Pacheco association, 0 to 2 percent slopes .... 132. Chumash-Malibu-Boades association, 30 to 75 percent slopes ..................... 143. Cotharin-Talepop-Rock outcrop complex, 30 to 75 percent slopes ................ 154. Mipolomol-Topanga-Sapwi association, 30 to 75 percent slopes ................... 165. Zumaridge-Rock outcrop-Kawenga association, 30 to 75 percent slopes ..... 176. Linne-Gaviota-Los Osos complex, 30 to 75 percent slopes ........................... 187. Botella-Cropley-Urban land complex, 0 to 9 percent slopes ........................... 198. Balcom-Xerorthents, landscaped-Urban land complex, 0 to 75 percent

slopes .............................................................................................................. 209. Cumulic Haploxerolls-Elder-Fluvaquents complex, 0 to 9 percent slopes ...... 2110. Urban land-Xerorthents, landscaped complex, 0 to 9 percent slopes ......... 22

Detailed Soil Map Units ........................................................................................... 23100—Chumash-Boades-Malibu association, 30 to 75 percent slopes .................. 24101—Chumash-Boades-Malibu association, 5 to 15 percent slopes .................... 27110—Malibu-Chumash-Boades association, 15 to 50 percent slopes .................. 29120—Mipolomol-Topanga association, 30 to 75 percent slopes ........................... 32121—Mipolomol-Topanga-Rock outcrop complex, 30 to 75 percent slopes ......... 34122—Calcic Haploxerepts-Mollic Haploxeralfs association, 30 to 75 percent

slopes .............................................................................................................. 36130—Camarillo loam, coastal, 0 to 2 percent slopes ............................................ 38140—Sulfic Fluvaquents, frequently flooded, 0 to 1 percent slopes ..................... 39150—Abaft-Beaches association, 0 to 5 percent slopes ....................................... 40151—Abaft-Beaches-Urban land complex, 0 to 5 percent slopes ........................ 42160—Xerorthents, landscaped, 0 to 9 percent slopes .......................................... 43170—Cotharin clay loam, 30 to 75 percent slopes ................................................ 44171—Cotharin loam-Rock outcrop complex, very bouldery, 30 to 75 percent

slopes .............................................................................................................. 46175—Cotharin-Talepop association, 30 to 75 percent slopes ............................... 47176—Cotharin-Talepop association, 15 to 50 percent slopes ............................... 49178—Cotharin-Talepop-Urban land complex, 0 to 50 percent slopes ................... 51

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179—Cotharin loam, 30 to 75 percent slopes, dry ................................................ 54180—Pits and Dumps ............................................................................................ 55190—Kayiwish association, 0 to 9 percent slopes ................................................ 56191—Kayiwish association, 9 to 30 percent slopes .............................................. 58200—Cumulic Haploxerolls, 0 to 9 percent slopes ................................................ 60202—Fluvaquents-Riverwash complex, 0 to 5 percent slopes.............................. 61220—Elder fine sandy loam, coastal, 0 to 2 percent slopes ................................. 62230—Cotharin-Talepop association, 15 to 50 percent slopes ............................... 64231—Talepop-Rock outcrop complex, 30 to 75 percent slopes ............................ 66240—Tongva-Cotharin-Rock outcrop complex, 30 to 75 percent slopes .............. 67241—Cotharin-Rock outcrop-Tongva complex, 30 to 75 percent slopes .............. 69250—Urban land-Xerorthents, landscaped, complex, 0 to 5 percent slopes ........ 72251—Urban land-Tongva complex, 0 to 15 percent slopes ................................... 73252—Urban land-Xerorthents, landscaped, complex, rarely flooded, 0 to 5

percent slopes ................................................................................................. 74270—Pacheco silty clay loam, 0 to 2 percent slopes ............................................ 76290—Topanga-Mipolomol-Sapwi association, 30 to 75 percent slopes ................ 77300—Zumaridge-Kawenga association, 30 to 75 percent slopes ......................... 79301—Zumaridge-Kawenga association, 15 to 50 percent slopes ......................... 82302—Zumaridge-Rock outcrop-Sumiwawa complex, very stony, 15 to 50

percent slopes ................................................................................................. 84303—Zumaridge-Rock outcrop-Sumiwawa complex, very stony, 30 to 75

percent slopes ................................................................................................. 86304—Zumaridge-Sapwi-Kawenga association, bouldery, 30 to 75 percent

slopes .............................................................................................................. 88305—Zumaridge-Rock outcrop complex, bouldery, 30 to 75 percent slopes ........ 91310—Gaviota stony sandy loam, 30 to 50 percent slopes .................................... 92311—Gaviota-Rock outcrop association, 50 to 100 percent slopes ..................... 94320—Botella loam, 2 to 9 percent slopes .............................................................. 95330—Linne-Los Osos-Haploxerepts association, 30 to 75 percent slopes ........... 96331—Linne silty clay loam, 15 to 50 percent slopes ............................................. 99332—Linne silty clay loam, 9 to 15 percent slopes ............................................. 100350—Los Osos clay loam, 30 to 50 percent slopes ............................................ 101390—Danville-Urban land complex, 0 to 9 percent slopes ................................. 103391—Danville-Urban land complex, 9 to 15 percent slopes ............................... 104400—Pachic Argixerolls, coastal, 30 to 75 percent slopes.................................. 105410—Lockwood-Urban land complex, 0 to 15 percent slopes ............................ 107411—Lockwood-Urban land complex, 0 to 9 percent slopes .............................. 108430—Cropley clay, 2 to 9 percent slopes ............................................................ 109431—Cropley association, 2 to 15 percent slopes .............................................. 110432—Cropley clay, 0 to 2 percent slopes ............................................................ 112433—Cropley, coastal-Urban land-Haploxererts complex, 0 to 30 percent

slopes ............................................................................................................ 114434—Cropley, coastal-Xerorthents, landscaped-Urban land complex, 0 to 9

percent slopes ............................................................................................... 116450—Sapwi loam, 30 to 75 percent slopes ......................................................... 118451—Urban land-Sapwi complex, 0 to 50 percent slopes .................................. 119460—Typic Haploxerepts, 30 to 50 percent slopes ............................................. 121461—Typic Haploxerepts, 15 to 30 percent slopes ............................................. 122470—Sumiwawa-Hipuk-Rock outcrop complex, 30 to 75 percent slopes ........... 123472—Rock outcrop-Sumiwawa-Hipuk complex, 30 to 75 percent slopes ........... 126500—Balcom silty clay loam, 30 to 50 percent slopes ........................................ 128503—Balcom-Balcom, dark surface association, 30 to 75 percent slopes ......... 129530—Xerorthents-Urban land-Balcom complex, 0 to 30 percent slopes ............ 131

Santa Monica Mountains National Recreation Area, California v

531—Xerorthents-Urban land-Balcom complex, 0 to 15 percent slopes ............ 133532—Xerorthents-Urban land-Pachic Argixerolls, gullied complex, 0 to 30

percent slopes ............................................................................................... 135540—Calcic Argixerolls, 30 to 75 percent slopes ................................................ 137550—Dam............................................................................................................ 139W—Water ............................................................................................................ 139

Use and Management of the Soils ........................................................................ 141Interpretive Ratings ............................................................................................. 141

Rating Class Terms ......................................................................................... 141Numerical Ratings ........................................................................................... 141

Land Capability Classification.............................................................................. 142Major Land Resource Areas ................................................................................ 143Prime Farmland and Other Important Farmland ................................................. 143

Prime Farmland ............................................................................................... 143Additional Farmland of Statewide Importance ................................................ 144

Rangeland ........................................................................................................... 144Characterization and Management ................................................................. 144Ecological Sites in the Survey Area ................................................................ 145

Wildlife ................................................................................................................. 150Urban and Recreational Uses ............................................................................. 152Engineering ......................................................................................................... 157

Building Site Development .............................................................................. 157Sanitary Facilities ............................................................................................ 159Construction Materials .................................................................................... 165Water Management ......................................................................................... 166

Soil Properties ........................................................................................................ 169Engineering Index Properties .............................................................................. 169Physical Properties .............................................................................................. 170Chemical Properties ............................................................................................ 171Erosion Properties ............................................................................................... 172Water Features .................................................................................................... 173Soil Features ........................................................................................................ 174

Classification of the Soils ..................................................................................... 177Taxonomic Units and Their Morphology .................................................................. 177

Abaft Series ......................................................................................................... 178Balcom Series ..................................................................................................... 179Boades Series ..................................................................................................... 180Botella Series ...................................................................................................... 181Calcic Argixerolls ................................................................................................. 182Calcic Haploxerepts ............................................................................................. 183Camarillo Series .................................................................................................. 184Chumash Series .................................................................................................. 186Cotharin Series .................................................................................................... 187Cropley Series ..................................................................................................... 188Cumulic Haploxerolls ........................................................................................... 189Danville Series ..................................................................................................... 190Elder Series ......................................................................................................... 191Fluvaquents ......................................................................................................... 192Gaviota Series ..................................................................................................... 194Haploxerepts ........................................................................................................ 195Haploxererts ........................................................................................................ 196Hipuk Series ........................................................................................................ 197Kawenga Series ................................................................................................... 198Kayiwish Series ................................................................................................... 199

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Linne Series ......................................................................................................... 200Lockwood Series ................................................................................................. 202Los Osos Series .................................................................................................. 203Malibu Series ....................................................................................................... 204Mipolomol Series ................................................................................................. 205Mollic Haploxeralfs ............................................................................................... 206Pacheco Series .................................................................................................... 207Pachic Argixerolls ................................................................................................ 208Sapwi Series ........................................................................................................ 209Sulfic Fluvaquents ............................................................................................... 211Sumiwawa Series ................................................................................................ 212Talepop Series ..................................................................................................... 213Tongva Series ...................................................................................................... 214Topanga Series .................................................................................................... 215Typic Haploxerepts .............................................................................................. 216Xerorthents .......................................................................................................... 217Zumaridge Series ................................................................................................ 218

Formation of the Soils ........................................................................................... 221Climate ................................................................................................................. 221Living Organisms ................................................................................................. 222Geomorphic Surfaces .......................................................................................... 223

References .............................................................................................................. 225Glossary .................................................................................................................. 227Tables ...................................................................................................................... 251

Table 1.—Temperature and Precipitation ............................................................ 252Table 2.—Freeze Dates in Spring and Fall .......................................................... 255Table 3.—Growing Season .................................................................................. 255Table 4.—Acreage and Proportionate Extent of the Soils ................................... 256Table 5.—Land Capability Classification ............................................................. 258Table 6.—Prime Farmland ................................................................................... 264Table 7.—Statewide Important Farmland ............................................................ 265Table 8.—Ecological Sites and Characteristic Plant Communities ...................... 266Table 9a.—Urban and Recreational Uses (Part 1) .............................................. 287Table 9b.—Urban and Recreational Uses (Part 2) .............................................. 300Table 10a.—Building Site Development (Part 1) ................................................. 312Table 10b.—Building Site Development (Part 2) .................................................. 325Table 11a.—Sanitary Facilities (Part 1) ............................................................... 337Table 11b.—Sanitary Facilities (Part 2) ............................................................... 352Table 12a.—Construction Materials (Part 1) ....................................................... 367Table 12b.—Construction Materials (Part 2) ........................................................ 383Table 13.—Water Management ........................................................................... 398Table 14.—Engineering Index Properties ............................................................ 410Table 15.—Physical Properties of the Soils ......................................................... 430Table 16.—Chemical Properties of the Soils ....................................................... 440Table 17.—Erosion Properties of the Soils .......................................................... 450Table 18.—Water Features .................................................................................. 460Table 19.—Soil Features ..................................................................................... 472Table 20.—Taxonomic Classification of the Soils ................................................ 482

Appendix ................................................................................................................. 483Appendix.—Index of Common and Scientific Plant Names and Plant

Symbols ......................................................................................................... 484

Issued 2006

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This soil survey contains information that affects land use planning in this surveyarea. It contains predictions of soil behavior for selected land uses. The survey alsohighlights soil limitations, improvements needed to overcome the limitations, and theimpact of selected land uses on the environment.

This soil survey is designed for many different users. Farmers, ranchers, foresters,and agronomists can use it to evaluate the potential of the soil and the managementneeded for maximum food and fiber production. Planners, community officials,engineers, developers, builders, and home buyers can use the survey to plan landuse, select sites for construction, and identify special practices needed to ensureproper performance. Conservationists, teachers, students, and specialists inrecreation, wildlife management, waste disposal, and pollution control can use thesurvey to help them understand, protect, and enhance the environment.

Various land use regulations of Federal, State, and local governments may imposespecial restrictions on land use or land treatment. The information in this report isintended to identify soil properties that are used in making various land use or landtreatment decisions. Statements made in this report are intended to help the landusers identify and reduce the effects of soil limitations on various land uses. Thelandowner or user is responsible for identifying and complying with existing laws andregulations.

Great differences in soil properties can occur within short distances. Some soilsare seasonally wet or subject to flooding. Some are shallow to bedrock. Some are toounstable to be used as a foundation for buildings or roads. Clayey or wet soils arepoorly suited to use as septic tank absorption fields. A high water table makes a soilpoorly suited to basements or underground installations.

These and many other soil properties that affect land use are described in this soilsurvey. Broad areas of soils are shown on the general soil map. The location of eachsoil is shown on the detailed soil maps. Each soil in the survey area is described.Information on specific uses is given for each soil. Help in using this publication andadditional information are available at the local office of the Natural ResourcesConservation Service or the Cooperative Extension Service.

Lincoln “Ed” BurtonState ConservationistNatural Resources Conservation Service

Foreword

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Sacramento

Los Angeles

San Francisco

¨

Location of Santa Monica Mountains National Recreation Area in California.

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By Alan R. Wasner, Natural Resources Conservation Service

Fieldwork by Alan R. Wasner and Kenneth J. Oster, Natural Resources ConservationService

Technical edit by Kit Paris, Natural Resources Conservation Service

United States Department of Agriculture, Natural Resources Conservation Service,in cooperation withUnited States Department of the Interior, National Park Service

SANTA MONICA MOUNTAINS NATIONAL RECREATION AREA is in the eastern part of VenturaCounty and the western part of Los Angeles County. The total area is 182,440 acres.The survey area is bordered on the northwest and west by the Ventura Area soilsurvey area; on the northeast by the Los Angeles, West San Fernando Valley Area,soil survey area; on the south by the Pacific Ocean; and on the east by areas of LosAngeles County that have not yet been mapped. The survey area includes the SantaMonica Mountains and a small part of the Oxnard Plain, where Point Mugu NavalBase is located.

General Nature of the Survey AreaThis section gives general information about the survey area. It discusses history

and development; physiography, relief, and drainage; water supply; agriculture; alteredsoils; fire history; soil slippage; and climate.

History and Development

The Santa Monica Mountains have a history of continuous human occupationdating back more than 8,000 years. They were home to two of the largest NativeAmerican tribes in California—the Chumash and Garielino/Tongva. Large villagesexisted throughout the range, as evidenced by the more than 1,000 archaeologicalsites currently known to be located within the National recreation area boundary. Thedensity of archaeological sites in this mountain range is one of the highest in theworld. The most significant impact on the soils occurred in the areas of large villages,where anthropic epipedons were formed, and as a result of the use of fire as amanagement tool. Anthropic epipedons have a dark surface layer that formed as aresult of long, continued use by humans. The disposal of bones and shells hassupplied calcium and phosphorus to the soils; thus, the level of these elements ishigher in these soils than in adjacent soils. Use of fire by the Indians probablyresulted in fewer shrubs and more grasses, annual herbs, and bulbs than are typicalof these soils today.

The first European explorer in the area was Cabrillo in 1542. During the

Soil Survey of

Santa Monica MountainsNational Recreation Area,California

2 Soil Survey of

colonization in the 1700’s and early 1800’s, Franciscans established missions toclaim the territory for Spain. Later, Spain granted tracts of land called “ranchos” toarmy veterans for raising cattle. In 1821, California became Mexican territory. Nineyears later, Mexico divided the ranchos into smaller ranches. In 1891, Frederick andMay Rindge purchased a large parcel of El Rancho Topanga Malibu Sequit. Thefamily’s resistance to urban development in Malibu resulted in a legacy of open spacein the Santa Monica Mountains (fig. 1).

The Santa Monica Mountains are dominantly steeply sloping mountain ranges witha few intervening flatter “valleys” and ocean terraces (fig. 2). Building sitedevelopment is dominantly in these flatter areas, although houses have been built onthe steeper slopes in a few areas, such as on the mountains above the Malibu area.Considerable alteration of the soils has occurred in these areas. See the “AlteredSoils” section for more detailed information.

In 1978, Congress established the Santa Monica Mountains National RecreationArea as part of the National park system. About 15 percent of the land in therecreation area is administered by the Federal government, about 22 percent isadministered by the California Department of Parks and Recreation, and about 53percent is privately owned. The major communities in the survey area are Malibu,Agoura, Calabasas, Monte Nido, Cornell, and Topanga.

Adjacent to the survey area are the major metropolitan areas of Los Angeles, theSan Fernando Valley, and many cities such as Thousand Oaks and Ventura, with anapproximate total population of 14 million, nearly 5 percent of the Nation’s totalpopulation. A large number of California State parks and beaches are within thesurvey area as well as many city and county parks and State and privateconservancy land (fig. 3).

Currently, the Santa Monica Mountains National Recreation Area protects thegreatest expanse of Mediterranean ecosystem in the National park system. It isgenerally considered the world’s largest “urban park,” because it is bounded by urbandevelopment.

Figure 1.—Cropley soils in an area of Rancho Sierra Vista. Boney Mountain is in background.

Santa Monica Mountains National Recreation Area, California 3

Physiography, Relief, and Drainage

The Santa Monica Mountains National Recreation Area is in the southeast cornerof Los Angeles County and the eastern part of Ventura County. The survey area isbounded on the east by the cities of Beverly Hills and Hollywood, on the north byThousand Oaks, on the west by Camarillo and Oxnard, and on the south by thePacific Ocean. The recreation area boundary on the south is at the high tide linealong the Pacific Ocean. The area is about 46 miles long and 8 miles wide.

The dominant landforms in the survey area are steep, rugged mountains and hills,marine terraces, and intervening valleys. The area drains dominantly toward thePacific Ocean. A narrow belt of marine terraces is along the ocean, extending westfrom Malibu to the Ventura County line. A few small valleys are throughout the area;Las Virgenes Canyon, La Jolla Valley, Seranno Valley, and Hidden Valley are the

Figure 2.—View of Malibu Creek. Fluvaquents and Riverwash are on thecreek bottom, and Sapwi soils are in areas of oak woodland.

4 Soil Survey of

largest ones. Elevation ranges from a few feet below sea level at the low tide mark inthe tidal flats to 3,111 feet above sea level at Sandstone Peak. Other notablemountains in the area are Laguna Peak, Castro Peak, Ladyface Mountain, CalabasasPeak, and Saddle Peak.

The recreation area can be divided into several geomorphic units. These includethe steep, rugged mountains dissected by 49 coastal drainageways, the marineterraces along the ocean, the intervening valleys, and the coastal salt marshes ofMugu and Malibu Lagoons.

The steep, rugged mountains are part of the Transverse Range GeomorphicProvince of California. Most of this land is open country because of the steepness ofthe terrain. The marine terraces along the Pacific Ocean are dissected bydrainageways originating in the adjacent hills and mountains. These terracesgenerally are used for building site development. Localized flooding can occur at themouth of the drainageways during periods of high rainfall. The intervening valleys areused as building sites or for agriculture. The recreation area includes parts of theCalleguas Creek and Malibu Creek Watersheds. Several reservoirs are in the area,including Encino Reservoir, Stone Canyon Reservoir, Malibu Lake Reservoir, andFranklin Canyon Reservoir. Mugu Lagoon is part of the Mugu Naval Air Station and isa Federally protected wildlife habitat area.

Water Supply

Water supply varies from city to city. Most of the water comes from California waterprojects, such as the California Aqueduct in the north and the Colorado River andOwens Valley water projects in the south. In some areas the reservoir water issupplemented with ground water.

Figure 3.—View of the city of Malibu, along a coastal beach. The beaches are visited by millions ofpeople each year.


Agriculture

Notable agriculture in the recreation area includes Broome and Thornhill Ranches,which manage cattle on the mountains at the west end of the area (fig. 4). Severalranches in Hidden Valley produce grass hay and raise horses. In Las VirgenesCanyon, the water district raises a small acreage of corn and has allowed sheep tograze the land after the harvest. Avocados and grapes are grown on hillsides inseveral small areas. Small areas scattered throughout the recreation area are usedas nursery farms for ornamental and native plants.

Altered Soils

Areas of altered soils in the recreation area are dominantly those that have beensubject to cut and fill operations in housing developments. These operations mix theexisting soil material with crushed rock material, creating a very mixed soil thatgenerally is classified as Xerorthents. The soils in cut areas can be shallow tobedrock, and those in fill areas are deeper.

Many of the “valleys” in the area historically have been under agriculture at sometime. These areas now commonly have very clayey soils that do not have a surfacelayer, which is at least partly a result of incorporation of the surface layer into thesubsoil during tillage operations. The areas probably once supported more nativebrush, but as a result of repeated burning by Indians and tillage by farmers, grass hasbecome dominant. In some areas, the historical tillage lines can be seen on theadjacent hillsides above the “valley,” with grass within the tillage area and heavy brushoutside of the tillage area. This probably occurs because the natural surface layer had

Figure 4.—View of Thornhill Ranch. Kayiwish soils are in the more gently sloping areas, andCotharin soils are in the more steeply sloping areas.

6 Soil Survey of

considerably less clay than the underlying subsoil, and brush is not suited to thealtered drainage and water holding capacity associated with the more clayey soils.

Some areas are artificially drained by the pumping of ground water, use ofupstream diversions, and channeling of water. Some drainageways have altereddrainage as a result of the deeply incised drainage channel. Sycamore Canyon is agood example.

Fire History

All of the land in the Santa Monica Mountains National Recreation Area hasburned at least once in the last 100 years. Some areas have burned as many as sixtimes. Fanned by the high Santa Ana winds, fire reduces most native shrubs tocharred stumps and ash. The dominant plant community in the mountains ischaparral, which is particularly susceptible to fire because of its thick growth and highconcentration of volatile oils. Fire is a natural process within the ecosystem of themountains (fig. 5).

Soil Slippage

Landslides are evident throughout the recreation area. Some of the landslideshave areas of deposition, but most do not because the deposited material hasbeen washed away in the steep canyon bottoms, forming new beaches or filling inbehind dams. The Rindge Dam is a good example. It is filled to the top withsediment.

The angle of repose is defined as the steepest angle that bare soil will maintain.For natural soils, the angle of repose is about 34 percent. In areas where the angle ishigher, soil and rocks are totally under the influence of gravity and may slide downhillunless anchored by plants. All of the soils in the Santa Monica Mountains that haveslopes of more than 34 percent are susceptible to soil slippage during dry periods.

Figure 5.—Area of Cotharin soils, showing the effects of the 1993 Green Meadows fire. This areapresently is heavily revegetated with chaparral.


During periods of intense rainfall, the angle of repose decreases, depending onfactors such as soil type and the amount of rainfall.

The underlying geology also influences the soil slippage potential. Soils that areparticularly susceptible to slippage, or unstable, are those that are underlain bydownslope-tilted sedimentary rock or by clay shale, those in areas of previous slides,and those that have parallel ridges underlain by basalt. The soils in this recreationarea have been rated for their slippage potential. These ratings are given in table 19.

Areas that have flat-lying sedimentary rock are susceptible to slippage undercertain conditions (moderately unstable). These areas are very rare in theSanta Monica Mountains. Areas that have sedimentary beds that are perpendicularto the soil slope are much less susceptible to soil slippage. The protruding bedsact as anchors or barriers to soil movement. The angle of geologic bedding canchange greatly over short distances; therefore, onsite investigation is recommended(fig. 6).

Climate

Prepared by the Natural Resources Conservation Service, National Water and Climate Center,Portland, Oregon.

The climate tables were created from data gathered at the climate stations atCanoga Park, Pierce College; Santa Monica Pier; and University of California, LosAngeles (UCLA), in California. Additional information was obtained from severalother precipitation-only climate stations in the region as well as from new officialprecipitation normals maps of California developed for the Natural ResourcesConservation Service by Oregon State University using the PRISM modeling system(See “Glossary”).

Thunderstorm days, relative humidity, percent sunshine, and wind information were

Figure 6.—Castro Peak, showing an uplifted sandstone fin surrounded by Sumiwawa soils.

8 Soil Survey of

estimated from data gathered at the First Order station at Los Angeles Civic Center,California.

Table 1 gives data on temperature and precipitation for the survey area asrecorded at Canoga Park, Pierce College; Santa Monica Pier; and UCLA in the period1961 to 1990. Extremes reported are for the period 1949 to 1999. Table 2 showsprobable dates of the first freeze in fall and the last freeze in spring as recorded atCanoga Park, Pierce College, in the period 1961 to 1990. Table 3 provides data onthe length of the growing season as recorded at Canoga Park, Pierce College, in theperiod 1961 to 1990.

In winter, the average temperature is 54.6 degrees F at Canoga Park, PierceCollege; 57.4 degrees at Santa Monica Pier; and 58.6 degrees at UCLA. The averagedaily minimum temperature in winter at these locations is 39.8 degrees,50.0 degrees, and 50.6 degrees, respectively. The lowest temperatures on record are18 degrees at Canoga Park, Pierce College, on February 6, 1989; 33 degrees atSanta Monica Pier on March 21, 1952; and 30 degrees at UCLA on January 4, 1949.

In summer, the average temperature is 74.6 degrees at Canoga Park, PierceCollege; 64.9 degrees at Santa Monica Pier; and 68.0 degrees at UCLA. The averagedaily maximum temperature in summer at these locations is 92.8 degrees, 68.8degrees, and 75.6 degrees, respectively. The highest temperatures on record are116 degrees at Canoga Park, Pierce College, on August 24, 1985; 104 degrees atSanta Monica Pier on September 26, 1963; and 108 degrees at UCLA onJanuary 26, 1990. The inland region north of the coastal mountains is considerablywarmer in the daytime during the warmest months than is the coastal strip.

Growing degree days are shown in table 1. They are equivalent to “heat units”.During the month, growing degree days accumulate by the amount that the averagetemperature each day exceeds a base temperature (50 degrees F). The normalmonthly accumulation is used to schedule single or successive plantings of a cropbetween the last freeze in spring and the first freeze in fall.

At Santa Monica Pier and UCLA, temperatures near 32 degrees are extremelyrare. The temperature has not been as low as 31 degrees at UCLA since 1957, and ithas never been that low at Santa Monica Pier. In contrast, at Canoga Park, PierceCollege, which is inland, frost is common in winter. The normal frost (32 degrees)season is from December 2 to March 4. At the higher elevations, frost is veryuncommon, but temperatures near or slightly below 32 degrees occur every fewyears.

The average annual precipitation across the survey area is quite variable,depending largely on elevation and location. In general, the coastal strip receives12 to 16 inches of precipitation per year. Precipitation increases inland, and thehighest locations near Malibu receive about 30 inches of precipitation in an averageyear. Most of the rest of the coastal mountains receive 20 to 27 inches annually.Officially, the average annual precipitation is 16.33 inches at Canoga Park, PierceCollege; 12.16 inches at Santa Monica Pier; and 16.25 inches at UCLA. At LechuzaPoint climate station, which is at an elevation of 1,600 feet and is in the Zuna Ridgearea of the western portion of the survey area, the average annual precipitation isabout 21 inches. The heaviest 1-day rainfall on record is 6.57 inches at Canoga Park,Pierce College, on November 29, 1970; 5.11 inches at Santa Monica Pier on January20, 1969; and 5.75 inches at UCLA, on January 26, 1956. Thunderstorms occur onaverage about 6 days each year, and they can occur in any month.

Snowfall is extremely rare in the survey area. At UCLA and Santa Monica Pier,there is no official record of measurable snowfall from the past 50 years. At CanogaPark, Pierce College, 0.5 inch of snow was recorded on February 8, 1989. At theLechuza Point climate station, 6.2 inches of snow was recorded on January 12, 1949.In general, the highest mountain locations in the survey area receive a few inches ofsnow every decade or so. Snow is extremely uncommon elsewhere in the area.


The average relative humidity is highly dependent on location. In general, thehighest humidity occurs along the ocean. In areas slightly inland, such as at theLos Angeles Civic Center, the average relative humidity in midafternoon is about50 percent; the highest nighttime humidity is about 65 percent in winter and85 percent in summer. The inland valleys north of the coastal hills are very dry,especially during the afternoon in summer, when the humidity typically drops to20 to 30 percent or lower. Generally, the sun shines 80 to 90 percent of the time insummer throughout the survey area, except along the beach and in June. In winter,the sun shines approximately 70 percent of the time in all areas. The prevailing windis highly dependent on location. At the Los Angeles Civic Center, the prevailing windis from the west in all months except December and January, when it is from thenortheast. The average windspeed is quite slow all year; it is highest, about 7 milesper hour, in February and March.

How This Survey Was MadeThis survey was made to provide information about the soils and miscellaneous

areas in the survey area. The information includes a description of the soils andmiscellaneous areas and their location and a discussion of their suitability,limitations, and management for specified uses. Soil scientists observed thesteepness, length, and shape of the slopes; the general pattern of drainage; thekinds of crops and native plants; and the kinds of bedrock. They dug many holes tostudy the soil profile, which is the sequence of natural layers, or horizons, in a soil.The profile extends from the surface down into the unconsolidated material in whichthe soil formed. The unconsolidated material is devoid of roots and other livingorganisms, except in fractures, and has not been changed by other biologicalactivity.

The soils and miscellaneous areas in the survey area are in an orderly pattern thatis related to the geology, landforms, relief, climate, and natural vegetation of the area.Each kind of soil and miscellaneous area is associated with a particular kind oflandform or with a segment of the landform. By observing the soils and miscellaneousareas in the survey area and relating their position to specific segments of thelandform, a soil scientist develops a concept or model of how they were formed. Thus,during mapping, this model enables the soil scientist to predict with a considerabledegree of accuracy the kind of soil or miscellaneous area at a specific location on thelandscape.

Commonly, individual soils on the landscape merge into one another as theircharacteristics gradually change. To construct an accurate soil map, however, soilscientists must determine the boundaries between the soils. They can observe only alimited number of soil profiles. Nevertheless, these observations, supplemented by anunderstanding of the soil-vegetation-landscape relationship, are sufficient to verifypredictions of the kinds of soil in an area and to determine the boundaries.

Soil scientists recorded the characteristics of the soil profiles that they studied.They noted soil color, texture, size and shape of soil aggregates, kind and amount ofrock fragments, distribution of plant roots, reaction, and other features that enablethem to identify soils. After describing the soils in the survey area and determiningtheir properties, the soil scientists assigned the soils to taxonomic classes (units).Taxonomic classes are concepts. Each taxonomic class has a set of soilcharacteristics with precisely defined limits. The classes are used as a basis forcomparison to classify soils systematically. Soil taxonomy, the system of taxonomicclassification used in the United States, is based mainly on the kind and character ofsoil properties and the arrangement of horizons within the profile. After the soilscientists classified and named the soils in the survey area, they compared theindividual soils with similar soils in the same taxonomic class in other areas so that

10 Soil Survey of

they could confirm data and assemble additional data based on experience andresearch.

While a soil survey is in progress, samples of some of the soils in the areagenerally are collected for laboratory analyses and for engineering tests. Soilscientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behaviorof the soils under different uses. Interpretations for all of the soils are field testedthrough observation of the soils in different uses and under different levels ofmanagement. Some interpretations are modified to fit local conditions, and some newinterpretations are developed to meet local needs. Data are assembled from othersources, such as research information, production records, and field experience ofspecialists.

Predictions about soil behavior are based not only on soil properties but also onsuch variables as climate and biological activity. Soil conditions are predictable overlong periods of time, but they are not predictable from year to year. For example, soilscientists can predict with a fairly high degree of accuracy that a given soil will have ahigh water table within certain depths in most years, but they cannot predict that ahigh water table will always be at a specific level in the soil on a specific date.

After soil scientists located and identified the significant natural bodies of soil in thesurvey area, they drew the boundaries of these bodies on aerial photographs andidentified each as a specific map unit. Aerial photographs show trees, buildings,fields, roads, and rivers, all of which help in locating boundaries accurately.

The soils in this survey area were mapped at two levels of detail. At the moredetailed level, map units are narrowly defined. Map unit boundaries were plotted andverified at closely spaced intervals. At the less detailed level, map units are broadlydefined. Boundaries were plotted and verified at wider intervals. The areas in thesurvey area that have slopes of less than 9 percent were mapped at the moredetailed level. These areas include La Jolla Valley, Serrano Valley, Hidden Valley, thecity of Malibu, Cheeseboro Canyon, Paramount Ranch, Diamond X Ranch, MalibuCreek State Park, parts of the cities of Topanga and Calabasas, and other lessnotable areas. The remaining hills and mountains are mapped at the less detailedlevel.

Survey Procedures

The general procedures followed in making this survey are described in the“National Soil Survey Handbook” of the Natural Resources Conservation Service(Available in the State office of the Natural Resources Conservation Service at Davis,California, or online at http://soils.usda.gov/technical/handbook/) and the “Soil SurveyManual” (Soil Survey Division Staff, 1993).

Before the fieldwork began, preliminary boundaries of slopes and landforms wereplotted stereoscopically on aerial photographs taken in 1984 and enlarged to a scaleof 1:24,000. Soil scientists studied U.S. Geological Survey topographic maps to relateland and image features. A reconnaissance was made by vehicle before thelandscape was traversed on foot.

Sample areas that represent the major landscapes in the survey area wereselected. These areas were investigated more closely than the rest of the surveyarea. Extensive notes were taken on the composition of map units in thesepreliminary study areas. As mapping progressed, these preliminary notes weremodified and a final assessment of the composition of the individual map units wasmade.

As the traverses were made, the soil scientists divided the landscape intolandforms or landform segments based on use and management of the soils. For

http://soils.usda.gov/technical/handbook/


example, a hill was separated from a depression and a gently sloping summit from avery steep backslope of a ridge.

Observations of landforms, excavations and trenches, vegetation, roadcuts, andanimal burrows were made without regard to spacing. Soil boundaries weredetermined based on soil examinations and observations and on photointerpretation.The soil material was examined, with the aid of a hand auger or spade, to a depth ofabout 6 feet or to bedrock if within a depth of 6 feet. The typical pedons wereobserved and studied in pits that were dug with shovels, spades, and backhoes.

Samples for analyses of chemical and physical properties and of engineeringproperties were taken from representative sites of several of the soils in the surveyarea. The chemical and physical analyses were made by the National Soil SurveyLaboratory, Natural Resources Conservation Service, Lincoln, Nebraska. The resultsof the analyses are stored in a computerized data file at the laboratory. A descriptionof the laboratory procedures can be obtained on request from the laboratory. Theresults of the studies are available at the State office of the Natural ResourcesConservation Service at Davis, California.

13

The general soil map with this publication shows broad areas that have adistinctive pattern of soils, relief, and drainage. Each map unit on the general soil mapis a unique natural landscape. Typically, it consists of one or more major soils ormiscellaneous areas and some minor soils or miscellaneous areas. It is named forthe major soils or miscellaneous areas, known as major components. Thecomponents of one map unit can occur in another but in a different pattern.

The general soil map can be used to compare the suitability of large areas forgeneral land uses. Areas of suitable soils can be identified on the map. Likewise,areas where the soils are not suitable can be identified.

Because of its small scale, the map is not suitable for planning the management ofa farm or field or for selecting a site for a road or building or other structure. The soilsin any one map unit differ from place to place in slope, depth, drainage, and othercharacteristics that affect management.

1. Sulfic Fluvaquents-Camarillo-Pacheco association,0 to 2 percent slopes

Very deep, nearly level and level, somewhat poorly drained to very poorly drainedsoils that formed in mixed alluvium; on flood plains and tidal flats

Setting

Landform: Flood plains and tidal flatsSlope: 0 to 2 percent

Composition

Extent of map unit in survey area: Less than 1 percentExtent of components in map unit:

Sulfic Fluvaquents—43 percentCamarillo—34 percentPacheco—21 percentMinor components—2 percent

Soil Properties and Qualities

Sulfic FluvaquentsDepth class: Very deepDrainage class: Very poorly drainedPosition on landform: Tidal flatsParent material: Alluvium derived from mixed sedimentSlope: Level

CamarilloDepth class: Very deepDrainage class: Somewhat poorly drainedPosition on landform: Flood plains

General Soil Map Units

14 Soil Survey of

Parent material: Alluvium derived from mixed sedimentSlope: Nearly level

PachecoDepth class: Very deepDrainage class: Poorly drainedPosition on landform: Flood plainsParent material: Alluvium derived from mixed sedimentSlope: Nearly level

Minor Components

Haploxerolls

Major Uses

Recreation and wildlife habitat

2. Chumash-Malibu-Boades association, 30 to 75percent slopes

Very shallow to moderately deep, steep and very steep, well drained andmoderately well drained soils derived from shale and sandstone; on hills andmountains

Setting

Landform: Hills and mountainsSlope: 30 to 75 percent

Composition

Extent of map unit in survey area: About 14 percentExtent of components in map unit:

Chumash—33 percentMalibu—24 percentBoades—24 percentMinor components—19 percent


ChumashDepth class: Very shallow and shallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstone and shaleSlope: Steep and very steep

MalibuDepth class: Moderately deepDrainage class: Moderately well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstone and shaleSlope: Steep and very steep

BoadesDepth class: ShallowDrainage class: Well drainedPosition on landform: Hills and mountains


Parent material: Residuum and colluvium derived from sandstone and shaleSlope: Steep and very steep

Minor Components

Cotharin soils, Pachic Argixerolls, Rock outcrop, Calcic Pachic Argixerolls, andCalcic Haploxerolls

Major Uses

Recreation and housing development

3. Cotharin-Talepop-Rock outcrop complex, 30 to 75percent slopes

Shallow, steep and very steep, well drained soils that formed in igneous volcanicrock, and Rock outcrop; on hills and mountains

Setting


Composition


Cotharin—69 percentTalepop—7 percentRock outcrop—7 percentMinor components—17 percent


CotharinDepth class: ShallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from metavolcanic rockSlope: Steep and very steep

TalepopDepth class: ShallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from metavolcanic rockSlope: Steep and very steep

Rock outcropPosition on landform: Hills and mountainsParent material: Igneous volcanic rockSlope: Steep and very steep

Minor Components

Kayiwish soils, Typic Haploxerolls, Pachic Argixerolls, Lithic Haploxerolls, CumulicHaploxerolls, Tongva soils, and Urban land

Major Uses


16 Soil Survey of

4. Mipolomol-Topanga-Sapwi association, 30 to 75percent slopes

Shallow and moderately deep, steep and very steep, well drained soils that formedin shale, sandstone, and slate; on hills and mountains

Setting


Composition


Mipolomol—38 percentTopanga—38 percentSapwi—8 percentMinor components—16 percent


MipolomolDepth class: ShallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstone and shaleSlope: Steep and very steep

TopangaDepth class: ShallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstone and shaleSlope: Steep and very steep

SapwiDepth class: Moderately deepDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstoneSlope: Steep and very steep

Minor Components

Boades soils, Pachic Argixerolls, Typic Palexerolls, Rock outcrop, Typic Argixerolls,Kawenga soils, and Urban land

Major Uses



5. Zumaridge-Rock outcrop-Kawenga association,30 to 75 percent slopes

Shallow and deep, steep and very steep, well drained soils derived from sandstone,and Rock outcrop; on hills and mountains

Setting


Composition


Zumaridge—28 percentRock outcrop—24 percentKawenga—10 percentMinor components—38 percent


ZumaridgeDepth class: ShallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstoneSlope: Steep and very steep

KawengaDepth class: DeepDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstoneSlope: Steep and very steep

Rock outcropPosition on landform: Hills and mountainsParent material: Sandstone and shaleSlope: Steep and very steep

Minor Components

Sapwi soils, Typic Argixerolls, Typic Haploxerolls, Gaviota and Sumiwawa soils,Typic Xeropsamments, Hipuk soils, and Lithic Xerorthents

Major Uses


18 Soil Survey of

6. Linne-Gaviota-Los Osos complex, 30 to 75 percentslopes

Very shallow and moderately deep, well drained soils derived from marine shale andsandstone; on hills and mountains

Setting


Composition


Linne—31 percentGaviota—22 percentLos Osos—14 percentMinor components—33 percent


LinneDepth class: Moderately deepDrainage class: Well drainedPosition on landform: HillsParent material: Residuum derived from marine shaleSlope: Steep and very steep

GaviotaDepth class: Very shallowDrainage class: Well drainedPosition on landform: Hills and mountainsParent material: Residuum and colluvium derived from sandstoneSlope: Steep and very steep

Los OsosDepth class: Moderately deepDrainage class: Well drainedPosition on landform: HillsParent material: Residuum and colluvium derived from marine shale and sandstoneSlope: Steep and very steep

Minor Components

Sapwi and Elder soils, Rock outcrop, Calcic Haploxerolls, Mollic Haploxerolls,Cropley soils, Xerorthents, Haploxerepts, Typic Argixerolls, and PachicArgixerolls

Major Uses



7. Botella-Cropley-Urban land complex, 0 to 9 percentslopes

Very deep, nearly level to moderately sloping, well drained soils that formed insedimentary material, and Urban land; on alluvial fans and hills

Setting

Landform: Hills and alluvial fansSlope: 0 to 30 percent

Composition


Botella—20 percentCropley—18 percentUrban land—15 percentMinor components—47 percent


BotellaDepth class: Very deepDrainage class: Well drainedPosition on landform: Alluvial fansParent material: Alluvium derived from sedimentary rockSlope: Gently sloping

CropleyDepth class: Very deepDrainage class: Well drainedPosition on landform: Alluvial fansParent material: Residuum and colluvium derived from sedimentary rockSlope: Nearly level to moderately sloping

Urban landPosition on landform: Hills and alluvial fansSlope: Nearly level

Minor Components

Danville and Abaft soils, Typic Xeropsamments, Beaches, Riverwash, TypicXerorthents, Elder soils, Pachic Argixerolls, Lockwood soils, and CumulicHaploxerolls

Major Uses


20 Soil Survey of

8. Balcom-Xerorthents, landscaped-Urban land complex,0 to 75 percent slopes

Shallow to very deep, nearly level to very steep, well drained soils derived from shaleand sandstone; on hills

Setting

Landform: HillsSlope: 0 to 75 percent

Composition


Balcom—50 percentXerorthents, landscaped—20 percentUrban land—18 percentMinor components—12 percent


BalcomDepth class: Moderately deepDrainage class: Well drainedPosition on landform: HillsParent material: Residuum derived from shale and sandstoneSlope: Steep and very steep

Xerorthents, landscapedDepth class: Shallow to deepDrainage class: Well drainedPosition on landform: HillsParent material: Residuum derived from marine shale and sandstoneSlope: Nearly level to moderately steep

Urban landPosition on landform: HillsDescription of areas: Houses and other buildings, streets, parking lots, and

association landscaped areasSlope: Nearly level to moderately steep

Minor Components

Urban land, Typic Xerochrepts, Botella soils, Typic Calcixerolls, Xerorthents,Rock outcrop, and Pachic Argixerolls

Major Uses



9. Cumulic Haploxerolls-Elder-Fluvaquents complex,0 to 9 percent slopes

Very deep, nearly level to gently rolling, well drained and very poorly drained soilsthat formed in alluvium derived from volcanic and sedimentary material; indrainageways

Setting

Landform: Inset fans and flood plainsSlope: 0 to 9 percent

Composition


Cumulic Haploxerolls—58 percentElder—17 percentFluvaquents—9 percentMinor components—16 percent


Cumulic HaploxerollsDepth class: Very deepDrainage class: Well drainedPosition on landform: Inset fansParent material: Alluvium derived from volcanic and sedimentary materialSlope: Nearly level to gently rolling

ElderDepth class: Very deepDrainage class: Well drainedPosition on landform: Flood plainsParent material: Alluvium derived from shale and sandstoneSlope: Nearly level

FluvaquentsDepth class: Very deepDrainage class: Very poorly drainedPosition on landform: Flood plainsParent material: Alluvium derived from volcanic and sedimentary materialSlope: Nearly level

Minor Components

Riverwash, Danville soils, Typic Argixerolls, and Botella soils

Major Uses


22

10. Urban land-Xerorthents, landscaped complex, 0 to 9percent slopes

Urban land, and shallow to very deep, level to moderately sloping, well drained soilsderived from sedimentary rock; on hills, mountains, valleys, and alluvial fans

Setting

Landform: Hills, mountains, valleys, and alluvial fansSlope: 0 to 9 percent

Composition


Urban land—69 percentXerorthents, landscaped—29 percentMinor components—2 percent


Urban landPosition on landform: Hills and mountainsDescription of areas: Houses and other buildings, streets, parking lots, and

association landscaped areasSlope: Level to moderately sloping

Xerorthents, landscapedDepth class: Shallow to very deepDrainage class: Well drainedPosition on landform: Hills, mountains, valleys, and alluvial fansParent material: Residuum and colluvium derived from sedimentary rockSlope: Level to moderately sloping

Minor Components

Elder soils

Major Uses

Housing and commercial building development, and recreation

23

The map units delineated on the detailed soil maps in this survey represent thesoils or miscellaneous areas in the survey area. The map unit descriptions in thissection, along with the maps, can be used to determine the suitability and potential ofa unit for specific uses. They also can be used to plan the management needed forthose uses. More information about each map unit is given under the heading “Useand Management of the Soils.”

A map unit delineation on a soil map represents an area dominated by one ormore major kinds of soil or miscellaneous areas. A map unit is identified and namedaccording to the taxonomic classification of the dominant soils. Within a taxonomicclass there are precisely defined limits for the properties of the soils. On thelandscape, however, the soils are natural phenomena, and they have thecharacteristic variability of all natural phenomena. Thus, the range of some observedproperties may extend beyond the limits defined for a taxonomic class. Areas of soilsof a single taxonomic class rarely, if ever, can be mapped without including areas ofother taxonomic classes. Consequently, every map unit is made up of the soils ormiscellaneous areas for which it is named and some minor components that belongto taxonomic classes other than those of the major soils.

Most minor soils have properties similar to those of the dominant soil or soils in themap unit, and thus they do not affect use and management. These are callednoncontrasting, or similar, components. They may or may not be mentioned in aparticular map unit description. Other minor components, however, have propertiesand behavioral characteristics divergent enough to affect use or to require differentmanagement. These are called contrasting, or dissimilar, components. They generallyare in small areas and could not be mapped separately because of the scale used.The contrasting components are mentioned in the map unit descriptions. A few areasof minor components may not have been observed, and consequently they are notmentioned in the descriptions, especially where the pattern was so complex that itwas impractical to make enough observations to identify all the soils andmiscellaneous areas on the landscape.

The presence of minor components in a map unit in no way diminishes theusefulness or accuracy of the data. The objective of mapping is not to delineate puretaxonomic classes but rather to separate the landscape into landforms or landformsegments that have similar use and management requirements. The delineation ofsuch segments on the map provides sufficient information for the development ofresource plans. If intensive use of small areas is planned, however, onsiteinvestigation is needed to define and locate the soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions.Each description includes general facts about the unit and gives the principal hazardsand limitations to be considered in planning for specific uses.

Soils that have profiles that are almost alike make up a soil series. Except fordifferences in texture of the surface layer, all the soils of a series have major horizonsthat are similar in composition, thickness, and arrangement.

Soils of one series can differ in texture of the surface layer, slope, stoniness,salinity, degree of erosion, and other characteristics that affect their use. On the basisof such differences, a soil series is divided into soil phases. Most of the areas shown

Detailed Soil Map Units

24 Soil Survey of

on the detailed soil maps are phases of soil series. The name of a soil phasecommonly indicates a feature that affects use or management. For example, Cropleyclay, 0 to 2 percent slopes, is a phase of the Cropley series.

Some map units are made up of two or more major soils or miscellaneous areas.These map units are complexes or associations.

A complex consists of two or more soils or miscellaneous areas in such an intricatepattern or in such small areas that they cannot be shown separately on the maps.The pattern and proportion of the soils or miscellaneous areas are somewhat similarin all areas. Danville-Urban land complex, 0 to 9 percent slopes, is an example.

An association is made up of two or more geographically associated soils ormiscellaneous areas that are shown as one unit on the maps. Because of present oranticipated uses of the map units in the survey area, it was not considered practicalor necessary to map the soils or miscellaneous areas separately. The pattern andrelative proportion of the soils or miscellaneous areas are somewhat similar.Chumash-Boades-Malibu association, 30 to 75 percent slopes, is an example.

This survey includes miscellaneous areas. Such areas have little or no soil materialand support little or no vegetation. Rock outcrop is an example.

Table 4 gives the acreage and proportionate extent of each map unit. Other tablesgive properties of the soils and the limitations, capabilities, and potentials for manyuses. The Glossary defines many of the terms used in describing the soils ormiscellaneous areas.

100—Chumash-Boades-Malibu association, 30 to 75percent slopes

Map Unit Setting

General location: Low-elevation coastal hills and mountainsMajor uses: Wildlife habitat, recreation, and building site developmentMajor land resource area (MLRA): 20—Southern California MountainsLandform: Hills and mountainsElevation: 5 to 1,545 feet (3 to 471 meters)Mean annual precipitation: 14 to 18 inches (360 to 457 millimeters)Mean annual air temperature: 60 to 64 degrees F (16 to 18 degrees C)Frost-free period: 290 to 350 days

Map Unit Composition

Chumash and similar soils—35 percentBoades and similar soils—25 percentMalibu and similar soils—25 percentMinor components—15 percent

Major Components

Chumash

Slope: 30 to 75 percentAspect (clockwise): Dominantly southwest to southeastLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from sandstone and shaleTypical vegetation: Grey coast eriogonum

Selected properties and qualitiesSurface pH: 6.8Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—4 to 22 inches


Slowest permeability class: Moderate above the bedrockSalinity: NonsalineSodicity: NonsodicAvailable water capacity to a depth of 60 inches: About 0.9 inch (very low)Shrink-swell potential: Moderate (LEP 3 to less than 6)Soil slippage potential: High

Selected hydrologic propertiesPresent annual flooding: NonePresent annual ponding: NoneSurface runoff: Very highCurrent water table: Not presentNatural drainage class: Somewhat excessively drainedHydrologic soil group: D

California land use interpretive groupsLand capability class (irrigated): Not calculatedLand capability class (nonirrigated): 7eFarmland classification: Not prime farmland or statewide important farmlandEcological site: R020XD041CA, Shallow Coastal Scrub 14-16" p.z.

Typical profileA—0 to 7 inches; gravelly loamCr—7 to 17 inches; soft, weathered bedrock

Boades

Slope: 30 to 75 percentAspect (clockwise): Dominantly northwest to northeastLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from sandstone and

shaleTypical vegetation: Coastal scrub

Selected properties and qualitiesSurface pH: 6.0Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—10 to 20 inchesSlowest permeability class: Moderately slow above the bedrockSalinity: NonsalineSodicity: NonsodicAvailable water capacity to a depth of 60 inches: About 1.6 inches (very low)Shrink-swell potential: Moderate (LEP 3 to less than 6)Soil slippage potential: High

Selected hydrologic propertiesPresent annual flooding: NonePresent annual ponding: NoneSurface runoff: Very highCurrent water table: Not presentNatural drainage class: Well drainedHydrologic soil group: D

California land use interpretive groupsLand capability class (irrigated): Not calculatedLand capability class (nonirrigated): 7eFarmland classification: Not prime farmland or statewide important farmlandEcological site: R020XD039CA, Coastal Scrub 14-16" p.z.

26 Soil Survey of

Typical profileA1—0 to 2 inches; loamA2—2 to 14 inches; loamCr—14 to 24 inches; soft, weathered bedrock

Malibu

Slope: 30 to 75 percentAspect (clockwise): Dominantly northeast to westLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from interbedded sandstone

and shaleTypical vegetation: Coastal scrub

Selected properties and qualitiesSurface pH: 6.4Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—20 to 40 inchesSlowest permeability class: Very slow above the bedrockSalinity: NonsalineSodicity: NonsodicAvailable water capacity to a depth of 60 inches: About 3.4 inches (low)Shrink-swell potential: Moderate (LEP 3 to less than 6)Soil slippage potential: High

Selected hydrologic propertiesPresent annual flooding: NonePresent annual ponding: NoneSurface runoff: Very highCurrent water table: Not presentNatural drainage class: Moderately well drainedHydrologic soil group: D


Typical profileA—0 to 19 inches; loam2Bt—19 to 27 inches; clay2Cr—27 to 37 inches; weathered bedrock

Minor Components

Pachic ArgixerollsPercentage of map unit: About 5 percentSlope: 15 to 50 percentLandform: Hills and mountains

Rock outcropPercentage of map unit: About 5 percentLandform: Hills and mountains

CotharinPercentage of map unit: About 5 percentSlope: 30 to 75 percentLandform: Hills and mountains


101—Chumash-Boades-Malibu association, 5 to 15percent slopes

Map Unit Setting

General location: Low-elevation coastal hills and mountainsMajor uses: Wildlife habitat, recreation, and building site developmentMajor land resource area (MLRA): 20—Southern California MountainsLandform: Hills and mountainsElevation: 150 to 895 feet (46 to 274 meters)Mean annual precipitation: 14 to 18 inches (360 to 457 millimeters)Mean annual air temperature: 60 to 64 degrees F (16 to 18 degrees C)Frost-free period: 290 to 350 days


Chumash and similar soils—35 percentBoades and similar soils—25 percentMalibu and similar soils—25 percentMinor components—15 percent

Major Components

Chumash

Slope: 5 to 15 percentAspect (clockwise): Dominantly northeast to southLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from sandstone and shaleTypical vegetation: Grey coast eriogonum

Selected properties and qualitiesSurface pH: 6.8Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—4 to 22 inchesSlowest permeability class: Moderate above the bedrockSalinity: NonsalineSodicity: NonsodicAvailable water capacity to a depth of 60 inches: About 1 inch (very low)Shrink-swell potential: Moderate (LEP 3 to less than 6)Soil slippage potential: High




28 Soil Survey of

Boades

Slope: 5 to 15 percentAspect (clockwise): Dominantly northeast to southLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from sandstone and shaleTypical vegetation: Coastal scrub

Selected properties and qualitiesSurface pH: 6.0Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—10 to 20 inchesSlowest permeability class: Moderately slow above the bedrockSalinity: NonsalineSodicity: NonsodicAvailable water capacity to a depth of 60 inches: About 1.6 inches (very low)Shrink-swell potential: Moderate (LEP 3 to less than 6)Soil slippage potential: High

Selected hydrologic propertiesPresent annual flooding: NonePresent annual ponding: NoneSurface runoff: Very highCurrent water table: Not presentNatural drainage class: Well drainedHydrologic soil group: D


Typical profileA1—0 to 2 inches; loamA2—2 to 14 inches; loamCr—14 to 24 inches; soft, weathered bedrock

Malibu

Slope: 5 to 15 percentAspect (clockwise): Dominantly northeast to southLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from interbedded sandstone

and shaleTypical vegetation: Coastal scrub



Selected hydrologic propertiesPresent annual flooding: NonePresent annual ponding: NoneSurface runoff: HighCurrent water table: Not presentNatural drainage class: Moderately well drainedHydrologic soil group: D



Minor Components

CotharinPercentage of map unit: About 5 percentSlope: 30 to 75 percentLandform: Hills and mountains

Pachic ArgixerollsPercentage of map unit: About 5 percentSlope: 15 to 50 percentLandform: Hills and mountains

Rock outcropPercentage of map unit: About 5 percentLandform: Hills and mountains

110—Malibu-Chumash-Boades association, 15 to 50percent slopes

Map Unit Setting

General location: Low-elevation coastal hills and mountainsMajor uses: Wildlife habitat, recreation, and building site developmentMajor land resource area (MLRA): 20—Southern California MountainsLandform: Hills and mountainsElevation: 75 to 1,545 feet (24 to 471 meters)Mean annual precipitation: 14 to 18 inches (360 to 457 millimeters)Mean annual air temperature: 60 to 64 degrees F (16 to 18 degrees C)Frost-free period: 290 to 350 days


Malibu and similar soils—35 percentChumash and similar soils—30 percentBoades and similar soils—25 percentMinor components—10 percent

30 Soil Survey of

Major Components

Malibu

Slope: 15 to 50 percentAspect (clockwise): Dominantly northeast to northwestLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from interbedded sandstone and

shaleTypical vegetation: Coastal scrub


Selected hydrologic propertiesPresent annual flooding: NonePresent annual ponding: NoneSurface runoff: Very highCurrent water table: Not presentNatural drainage class: Moderately well drainedHydrologic soil group: D



Chumash

Slope: 15 to 50 percentAspect (clockwise): Dominantly northeast to northwestLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from sandstone and

shaleTypical vegetation: Grey coast eriogonum

Selected properties and qualitiesSurface pH: 6.8Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—4 to 22 inchesSlowest permeability class: Moderate above the bedrockSalinity: NonsalineSodicity: NonsodicAvailable water capacity to a depth of 60 inches: About 0.9 inch (very low)


Shrink-swell potential: Moderate (LEP 3 to less than 6)Soil slippage potential: High




Boades

Slope: 15 to 50 percentAspect (clockwise): Dominantly northeast to northwestLandform: Hills and mountainsParent material: Colluvium and/or residuum derived from sandstone and shaleTypical vegetation: Coastal scrub

Selected properties and qualitiesSurface pH: 6.0Surface area covered with coarse fragments: NoneDepth to restrictive feature: Bedrock (paralithic)—10 to 20 inchesSlowest permeability class: Moderately slow above the bedrockSalinit

soil survey of santa monica mountains national recreation ......mountains national recreation area,...

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