LOCATION MARPOL CAEstablished Series
The Marpol series consists of deep, moderately well drained soils that formed in residuum from quartz-diorite.. Marpol soils are on side slopes of interfluves of hills and mountains. The mean annual precipitation is about 355 millimeters (14 inches) and the mean annual temperature is about 21 degrees C (69 degrees F). Slopes range from 25 to 70 percent
TAXONOMIC CLASS: Fine, mixed, superactive, thermic Typic Palexerolls
TYPICAL PEDON: Marpol gravelly loam, on a south west facing 60 percent slope under a cover of sage and grass at an elevation of 1234 feet, (376 m). (Colors are for dry soil observed on a broken face of the ped unless otherwise noted).
A--0 to 1 inches, (0 to 3 cm); brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; 14 percent clay; moderate thick platy structure; soft, very friable, slightly sticky, slightly plastic; common very fine interstitial pores; 15 percent rounded 2 to 75 millimeter quartz-diorite fragments; neutral, (pH 7.1 by pH meter 1:1 water); abrupt wavy boundary. (3 to 70 centimeters thick)
Bt1--1 to 9 inches, (3 to 25 cm); brown (7.5YR 5/3) clay loam, dark brown (7.5YR 3/3) moist; 35 percent clay; moderate medium subangular blocky structure; moderately hard, friable, moderately sticky, moderately plastic; common very fine tubular and common very fine interstitial pores; discontinuous distinct clay films on all faces of peds and on rock fragments; 5 percent angular 2 to 75 millimeter quartz-diorite fragments; slightly alkaline (pH 7.5 by pH meter 1:1 water); clear wavy boundary. (5 to 16 centimeters thick)
Bt2--9 to 28 inches, (24 to 70 cm); brown (7.5YR 5/4) clay, strong brown (7.5YR 4/6) moist; 50 percent clay; strong coarse subangular blocky structure; hard, firm, very sticky, very plastic; continuous prominent clay films on all faces of peds and discontinuous prominent clay films on rock fragments; 5 percent angular 2 to 75 millimeter quartz-diorite fragments; slightly alkaline, (pH 7.7 by pH meter 1:1 water); gradual wavy boundary. (25 to 50 centimeters thick)
Bt3--28 to 41 inches, (70 to 105 cm); brown (7.5YR 5/4) clay, strong brown (7.5YR 4/6) moist; 45 percent clay; massive; very hard, firm, very sticky, very plastic; continuous distinct clay films on all faces of peds; few iron-manganese masses and masses of oxidized iron; 5 percent angular 2 to 75 millimeter quartz-diorite fragments; slightly alkaline, (pH 7.6 by pH meter 1:1 water); abrupt irregular boundary. (10 to 40 centimeters thick)
R--41 to 45 inches, (105 to 115 cm); strongly cemented quartz-diorite porphyry bedrock.
TYPE LOCATION: Santa Catalina Island, Los Angeles County, California, in the Channel Islands Soil Survey Area 33 degrees, 18 minutes, 47 seconds North latitude and 118 degrees, 19 minutes, 8 seconds West longitude, NAD83 - U.S.G.S Quad: Santa Catalina East.
RANGE IN CHARACTERISTICS: Depth to bedrock is greater than 100 cm to paralithic or lithic contact. The mean annual soil temperature is 15 to 22 degrees C. (59 to 71 degrees F.) The soil moisture control section is dry in all parts from about mid-June to mid-November and is usually moist the rest of the time.
An Oi horizon can be present and consist of oak litter or grass.
Thickness ranges between 1 and 4 cm.
The A horizon dry color is 10YR 5/4, 5/3, 4/3, 4/2, 3/2, 7.5YR 5/3. Moist color is 10YR 3/3, 3/2, 2/2, 7.5YR 3/2.
Textures are sandy loam, loam, gravely loam and gravely sandy loam.
Clay percentage ranges from 5 to 14 percent.
Rock fragments range from 5 to 20.
The Bt1 and Bt2 horizon dry color is 10YR 6/4, 5/6, 4/3, 3/3, 7.5YR 5/4, 5/6, 2.5Y 5/4. Moist color is 10YR 4/4, 4/3, 3/3, 3/2, 7.5YR 4/6, 4/4, 2.5Y 4/4.
Textures are clay loam, sandy loam, clay and silty clay loam.
Clay percentage ranges from 25 to 50 percent.
Rock fragments range from 5 to 10.
The Bt3 horizon dry color is 10YR 6/4, 7.5YR 5/6, 5/4, 2.5Y 6/4, 5/4. Moist color is 10YR 4/4, 3/4, 7.5YR 4/6, 4/4, 2.5Y 4/4.
Textures are clay loam, sandy loam, clay, gravely to extremely gravely clay loam.
Clay percentage ranges from 35 to 50 percent.
Rock fragments range from 5 to 30.
The mollic horizon ranges from 25 to 70 cm from the soil surface and in some profiles the upper part of the argillic.
The bedrock ranges from angular indurated quartz-diorite rock fractured greater than 10 cm apart to hard quartz-diorite rock fractured less then 10 cm apart.
COMPETING SERIES: These are the Gonzaga soils. Gonzaga soils are well drained and formed in residuum weathered from siltstone.
GEOGRAPHIC SETTING: Marpol soils formed in quartz-diorite (typically porphyry) on interfluves of hills and mountains on islands. Slopes range from 20 to 70 percent. Elevations are from sea level to 1550 feet (0 to 472 meters). The climate is characterized by warm, dry summers and cool, moist winters with potential fog common all year. The mean annual precipitation is 13 to 24 inches (330 to 660 mm), the mean annual temperature is 61 to 73 degrees F. (16 to 23 degrees C.), and the frost free season is 355 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Nauti and Flyer soils. The Nauti soils are fine-loamy and moderately deep. Flyer soils are coarse-loamy and do not have a mollic epipedon.
DRAINAGE AND PERMEABILITY: moderately well drained; high runoff; moderately slow permeability. The soils are not flooded for any period.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is predominately Coastal Sage Scrub and Non-native Scrub, Maritime Cactus Scrub, Island Chaparral.
DISTRIBUTION AND EXTENT: Santa Catalina Island, Los Angeles County, California. The soil is not extensive. MLRA 20 Southern California Mountains.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES PROPOSED: Santa Catalina Island, Los Angeles County, California, 2006.
REMARKS: The series name is coined. Diagnostic horizons and features recognized in this pedon:
Particle Size Control Section for this pedon: 1.2 to 21 inches (3 to 53 cm).
Diagnostic horizons and features recognized in this pedon are:
Mollic Epipedon 0 to 25 cm
Argillic Horizon 3 to 105 cm
Abrupt textural change of 20 percent or more clay increase, and there is no horizon decreasing in clay 20 percent from the surface to bedrock.