LOCATION PENASCO NMEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, mesic, shallow Petrocalcic Calciustolls
TYPICAL PEDON: Penasco cobbly loam, rangeland. (Colors are for dry soil unless otherwise noted.)
A11--0 to 3 inches; dark grayish brown (10YR 4/2) very cobbly loam, very dark grayish brown (10YR 3/2) moist; weak fine granular and weak fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many fine and very fine roots; common very fine tubular pores; 10 percent gravel, 60 percent of surface is covered with gravel, cobblestones and few stones; slightly calcareous; moderately alkaline; abrupt smooth boundary. (1 to 6 inches thick)
A12--3 to 9 inches; dark grayish brown (10YR 4/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many fine and very fine roots; common very fine tubular pores; 35 percent gravel and 5 percent cobblestones; moderately calcareous with carbonate on rock fragments; moderately alkaline; abrupt wavy boundary. (3 to 6 inches thick)
C1ca--9 to 12 inches; brown (10YR 5/3) very gravelly loam, dark brown (10YR 4/3) moist; massive; slightly hard, very friable, slightly sticky, slightly plastic; common very fine roots; few very fine tubular pores; 40 percent gravel and 5 percent cobblestones; strongly calcareous, with carbonate on rock fragments and indurated carbonate fragments; moderately alkaline; abrupt wavy boundary. (3 to 8 inches thick)
C2cam--12 to 17 inches; white (N 8/) continuous indurated carbonate material containing few fractures; laminar in upper part; abrupt wavy boundary. (5 to 10 inches thick)
C3ca--17 to 30 inches; white (N 8/) weakly and moderately cemented carbonate material; 40 percent gravel and cobblestones, becoming noncemented below depth of 30 inches.
TYPE LOCATION: Chaves County, New Mexico; about 50 miles southwest of Roswell; 0.1 mile north of fence corner north of windmill in the NE1/4 NE1/4 of section 11, T.15S., R.17E.
RANGE IN CHARACTERISTICS: The depth to the Ccam horizon ranges from 7 to 20 inches. Rock fragments are limestone and indurated carbonate gravel, cobbles and stones with gravel making up about 30 percent, cobblestones about 10 percent, and stones about 3 percent. The control section averages more than 40 percent carbonate. The annual soil temperature ranges from 55 to 58 degrees F. The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 3 or 4 moist, and chroma of 2 or 3 dry and moist. It is gravelly loam, cobbly loam or loam with 18 to 27 percent clay and 20 to 40 percent rock fragments. The C1ca horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3 dry and moist. It is gravelly loam, gravelly clay loam, cobbly loam, cobbly clay loam with 18 to 35 percent clay and 40 to 60 percent rock fragments. This horizon is massive or has weak fine subangular blocky structure. The C2cam horizon ranges from severely fractured, indurated to continuously indurated. The C3ca horizon ranges from non through strongly cemented gravel and cobblestone carbonate material.
COMPETING SERIES AND THEIR DIFFERENTIAE: These are the Boracho, Jimenez, Olmos, Plack, and Valco series. Boracho soils have mixed mineralogy and a thermic temperature regime. Jimenez and Olmos soils have a hyperthermic temperature regime and Jimenez soils have mixed mineralogy. Plack and Valco soils lack a skeletal control section and Valco soils have a hyperthermic temperature regime.
SETTING: These soils are on nearly level to strongly sloping valley side slopes and fans at elevations of 5,500 to 6,200 feet. Slopes are dominantly 2 to 9 percent but range to 15 percent. The soils formed in calcareous, gravelly, cobbly alluvium from limestone. The climate is semiarid with rainfall of about 16 to 18 inches. The driest periods occur between late September and May. The annual temperature is 55 to 57 degrees F.
PRINCIPAL ASSOCIATED SOILS: These are the Deama, Galbaldon, Pena and Remunda soils. Deama soils are underlain by limestone bedrock at depths of less than 20 inches. Galbaldon soils have a cumulic surface horizon and a fine, silty control section. Pena soils have a skeletal control section and lack a petrocalcic horizon. Remunda soils have a fine control section and an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderate permeability down to the Ccam horizon.
USE AND VEGETATION: Grazing and wildlife. Vegetation is mainly blue grama, threeawn, wolftail, muhly, yucca, cholla and juniper.
DISTRIBUTION AND EXTENT: Southeastern New Mexico. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Chaves County, Southern Part, New Mexico, 1974.
REMARKS: Penasco soils were formerly classified as Lithosols.