LOCATION RITIDIAN GU+ PBEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, carbonatic, isohyperthermic Lithic Ustorthents
TYPICAL PEDON: Ritidian extremely cobbly clay loam, on an 8 percent slope under forest. (Colors are for moist soil unless otherwise stated. Textures are apparent field textures.)
A1--0 to 1 inch; dark reddish brown (5YR 3/3) extremely cobbly clay loam, dark reddish brown (5YR 3/4) dry; strong medium granular structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine roots, common medium roots and few coarse roots; many very fine, fine and medium pores; about 30 percent gravel and 40 percent cobbles that are angular, porous coralline limestone fragments; sand grains and rock fragments are weakly effervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (0.5 to 2 inches thick)
A2--1 to 4 inches; reddish brown (5YR 4/4) extremely cobbly clay loam, yellowish red (5YR 4/6) dry; weak very fine granular structure; soft, very friable slightly sticky and slightly plastic; many very fine and fine roots, common medium roots and few coarse roots; many very fine and few fine interstitial pores; about 30 percent gravel and 40 percent cobbles, all as angular porous coralline limestone fragments; many very fine nodules that crush to silty clay; weakly effervescent; moderately alkaline (pH 7.9); abrupt irregular boundary. (0 to 9 inches thick)
2R--4 inches; unweathered white coralline limestone, very angular and porous, many cracks and fissures which are stained with soil and organic material, and which contain roots along the rock faces; strongly alkaline (pH 8.6, 1:1 water)
TYPE LOCATION: Guam; about l.7 miles north of the entrance to Andersen South (Marbo Annex) Air Force Housing area on Route 15, about 200 yards along a jeep road to the east, 10 yards east of the road; lat. 13 degrees 31 minutes 12 seconds N. and long. 144 degrees 53 minutes 40 seconds E.
RANGE IN CHARACTERISTICS:
Soil moisture - Not continuously moist in all parts of the moisture control section for 90 to 120 days during the year, primarily between February and May. Soil is usually moist from July through November.
Mean annual soil temperature - 77 to 86 degrees F., with less than 4 degrees F. difference between summer and winter.
Percent clay - Dominantly 35 to 60 percent.
Rock fragments - 40 to 80 percent, about two-thirds as cobbles and one-third as gravel.
Depth to bedrock - 2 to 10 inches.
A horizon - Color: 5YR 2/2, 3/2, 3/3, 3/4, 4/4, 4/6, 2.5YR 3/4, 3/6, 7.5YR 3/2.
Texture, fine earth fraction: Clay loam or clay.
Reaction: Neutral or slightly alkaline.
COMPETING SERIES: None.
GEOGRAPHIC SETTING: Ritidian soils are on limestone plateaus and escarpments. Slopes range from 3 to 99 percent. The soils formed in slope alluvium, loess, and residuum from porous coralline limestone. Elevation ranges from sea level to about 1,300 feet. Mean annual temperature is 79 degrees F., with less than 4 degrees F. difference between summer and winter.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Guam, Pulantat, and Shioya soils. Guam soils are 4 to 20 inches deep throughout and have less than 35 percent coarse fragments in the profile. Pulantat soils are 10 to 20 inches deep. Shioya soils are deep and sandy.
DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability; slow to high runoff depending upon slope;
USE AND VEGETATION: This soil is used for wildlife habitat and as watershed. Vegetation is native forest.
DISTRIBUTION AND EXTENT: Ritidian soils are on the island of Guam, mostly in the north. They are inextensive, with about 7.500 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Guam; July 1985.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - From the surface to 4 inches.
Lithic contact - At 4 inches.
Taxonomic Version: Keys to Soil Taxonomy, 10th edition 2006.