LOCATION GAMBOA CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Pachic Haploxerolls
TYPICAL PEDON: Gamboa very gravelly very fine sandy loam, under redwood trees. (Colors are for dry soil unless otherwise noted.)
Oi--2 inches to 0; litter mainly from redwood leaf fall; moderately acid (pH 6.0); abrupt wavy boundary. (1/4 to 5 inches thick)
A11--0 to 23 inches; very dark gray (10YR 3/1) very gravelly very fine sandy loam, black (10YR 2/1) moist; weak fine crumb structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and common medium and coarse roots; many very fine interstitial pores; 60 percent angular gravel; slightly alkaline (pH 7.4); clear wavy boundary. (15 to 23 inches thick)
A12--23 to 30 inches; very dark gray (10YR 3/1) very gravelly fine sandy loam, black (10YR 2/1) moist; massive; soft, very friable, nonsticky and nonplastic; many very fine and fine, common medium and coarse roots; many very fine interstitial pores; 60 percent angular gravel; white mycelial mold is strongly acid (pH 5.5); soil neutral (pH 7.2); gradual wavy boundary. (6 to 20 inches thick)
A13--30 to 59 inches; very dark grayish brown (10YR 3/2) extremely gravelly fine sandy loam, very dark brown (10YR 2/2) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine, fine and coarse, many medium roots; many very fine interstitial pores; 75 percent angular pebbles, cobblestones, and stones; neutral (pH 7.0); clear wavy boundary. (19 to 30 inches thick)
R--59 to 72 inches; light brownish gray (2.5Y 6/2) hard sandstone with fractures more than 4 inches apart; few very fine, fine, medium and coarse roots in fractures. Some soil material in rock fractures.
TYPE LOCATION: Monterey County, California; about 1/2 mile east of U.S. Forest Service Ranger Station at Pacific Valley; near the east 1/4 corner of sec. 18, T.23S., R.5E.
RANGE IN CHARACTERISTICS: Depth to a lithic contact ranges from 40 to 60 inches. The mean soil temperature at a depth of 20 inches is 54 to 58 degrees F., and the soil temperature at that depth is always above 41 degrees F. The soil below the upper few inches is continuously moist from sometime in October or November until sometime in June or July and is dry all the rest of the time. Organic matter is 2 to 4 percent and decreases regularly to less than 1 percent at depths of 30 to 40 inches. Pebbles, cobblestones, and larger stones make up 35 to 70 percent of the volume. Base saturation is more than 75 percent throughout the upper 30 inches. The soils are slightly alkaline to moderately acid.
The A horizon is black, very dark gray, dark gray, gray, very dark grayish brown, dark grayish brown, grayish brown, very dark brown or dark brown in hue of 10YR; moist colors are very dark grayish brown, very dark brown, or dark brown in hues of 7.5YR and 10YR. It is loam, very fine sandy loam or sandy loam, has less than 18 percent clay and is modified as gravelly or very gravelly.
COMPETING SERIES: These are the Dehlinger (t), Lucia (t), Packard, and Wrentham series. Dehlinger soils are loam or clay loam, have 18 to 30 percent clay and have a frost-free period of 60 to 150 days. Lucia soils have a lithic contact of shale at depths of 24 to 40 inches. Packard soils lack either a lithic or paralithic contact. Wrentham soils have a lithic contact at depths of 20 to 40 inches and have a mean annual soil temperature of 47 to 54 degrees F.
GEOGRAPHIC SETTING: Gamboa soils are on mountain slopes and canyon sides. Slopes are 50 to 100 percent. Elevations are from near sea level to 3,500 feet. The soils formed in material weathered from noncalcareous sandstone, shale, schistose, or granitic rocks. The climate is moist humid, mesothermal. Summers are warm with much fog but little rain. Winters are cool and moist. Mean annual precipitation is 30 to 70 inches. The average January temperature is about 48 degrees F.; average July temperature is about 60 degrees F.; mean annual temperature is about 54 degrees F. The freeze-free season ranges from 200 to 300 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Junipero, Plaskett, Sheridan and Sur soils. Junipero soils have a paralithic contact at depths of 28 to 40 inches and have a base saturation of 50 to 75 percent in some part. Plaskett soils have less than 1 percent organic matter between depths of 10 and 20 inches. Sheridan soils have less than 15 percent rock fragments in the solum. Sur soils have a lithic contact at depths of 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; rapid runoff; rapid permeability.
USE AND VEGETATION: Used for watershed, wildlife, and recreation. Vegetation is mainly coast redwood, laurel, madrone, and tanoak with an understory of poison oak and sword fern
DISTRIBUTION AND EXTENT: Canyons and north-facing slopes in the south-central coastal area of California. The series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Monterey County, California, 1972.
REMARKS: The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
OSED scanned by SSQA. Last revised by state on 6/76.