LOCATION RIMROCK AZEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Leptic Haplotorrerts
TYPICAL PEDON: Rimrock cobbly clay.
A--0 to 2 inches; reddish brown (5YR 4/4) cobbly clay, dark reddish brown (5YR 3/4) moist; moderate, fine and medium granular structure; slightly hard friable, sticky and plastic; common fine roots; common very fine and fine tubular pores; 20 percent cobbles; 15 percent gravel; slightly effervescent; moderately alkaline (pH 8.0); abrupt smooth boundary. (1 to 3 inches thick)
C--2 to 11 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; massive; very hard, firm, sticky and very plastic; few fine roots; common very fine and fine tubular pores; few pebbles and cobbles; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (7 to 10 inches thick)
Css--11 to 34 inches; reddish brown (5YR 4/4) clay, dark reddish brown (5YR 3/4) moist; massive; very hard, firm, sticky and very plastic; very few very fine and fine roots; common very fine and fine tubular pores; few pebbles and cobbles; many medium and large intersecting slickensides; strongly effervescent; moderately alkaline (pH 8.4); clear smooth boundary. (10 to 30 inches thick)
R--34 inches; very hard tuff and volcanic ash.
TYPE LOCATION: Yavapai County, Arizona;SE1/4 NW 1/4 Sec. 30, T. 13 N., R. 6 E.
RANGE IN CHARACTERISTICS:
Soil moisture: Ustic aridic moisture regime
Depth to tuff, cinders, ash or basalt: 20 to 40 inches
Coarse fragments of gravel, cobbles and stones: range from few to as much as 30 percent on the surface and throughout the profile.
Calcium carbonate: The soil may or may not effervesce to dilute HC1 and secondary carbonate masses and hard nodules may or may not occur.
A horizon
Hue: 7.5YR through 2.5YR, but is dominantly 5YR
Value: 3 through 5 dry and 2 through 4 moist
Chroma: 2 through 4
Structure: normally moderate and strong fine granular, but a weak thin platy structure may develop on the immediate surface.
C horizon
Hue: of 7.5YR to 2.5YR, but is dominantly 5YR
Value: 3 through 5 dry and 2 through 4 moist
Chroma: 2 through 4
Texture: clay or silty clay
Vertic features: cracks 1 cm or more are present and are normally never closed for 60 consecutive days. Intersecting slickensides are always present at some depth below 10 inches and above bedrock.
Calcium carbonate: Masses and hard nodules of secondary carbonates may occur above the basalt, cinders, ash or tuff.
COMPETING SERIES: This is the Paramore (AZ) series. Paramore soils are in MLRA 41, do not have secondary calcium carbonate, and are neutral to slightly alkaline.
GEOGRAPHIC SETTING: Rimrock soils are on nearly level to rolling uplands. Slopes are dominantly 0 to 5 percent, but may range up to 10 percent. The soils formed on cinders, ash, tuff and basalt. The annual precipitation ranges from 8 to 14 inches. The mean annual temperature ranges from 60 degrees F. to 68 degrees F.; the January mean is about 41 degrees F., and the July mean about 78 degrees F. The frost-free season is from 180 to 240 days. Elevations range from 2,300 to 5,000 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Lehmans, Cellar, House Mountain, Continental, Palos Verdes, Retriever, Guest and Graham soils. The Lehmans, Cellar, House Mountain, Retriever and Graham soils are all shallow soils with bedrock at 20 inches or less. Palos Verdes soils are fine-loamy. Continental soils have an argillic and calcic horizon. Guest soils are Vertic Torrifluvents with mixed mineralogy.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is very slow on dry soils, but high on moist soils. Permeability is very slow.
USE AND VEGETATION: Used only as rangeland. Vegetation consists of scattered mesquite, catclaw, crucifixion, thorn, pricklypear, tobosa, filaree and annual grasses.
DISTRIBUTION AND EXTENT: Central and southern Arizona, associated with basic volcanic materials. The soils are moderately extensive. MLRAs 38 & 39.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Long Valley Area, Arizona; 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 2 inch (A horizon)
Vertic properties - Slickensides are common throughout the soil, and evidence of churning is apparent in the gilgai relief.