Established Series


The Bofecillos series consists of very shallow, well drained soils formed in residuum and colluvium weathered from basalt bedrock. Bofecillos soils are on mountains, hills, and plateaus and have slopes of 1 to 70 percent. Mean annual precipitation is about 13 inches and mean annual air temperature is about 65 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, calcareous, thermic Lithic Ustic Torriorthents

TYPICAL PEDON: Bofecillos very gravelly sandy clay loam - rangeland. (Colors are for dry soil unless otherwise stated.

A--0 to 4 inches; brown (10YR 5/3) very gravelly sandy clay loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to weak fine subangular blocky structure; common very fine roots throughout; 1 percent fine irregular carbonate nodules around rock fragments; 55 percent subangular basalt gravel with thin coatings of carbonate; strongly effervescent; slightly alkaline; very abrupt smooth boundary. (4 to 10 inches thick)

R--4 inches; gray (10YR 5/1) basalt bedrock; slightly effervescent.

TYPE LOCATION: Presidio County, Texas; from junction of US Highway 67 and FM Road 170 in Presidio, 7.8 miles east on FM 170, 6.0 miles north on Casa Piedra Road to junction, 19.8 miles east on road to Sauceda Ranch Headquarters, Big Bend Ranch State Park, east from Sauceda Ranch Headquarters 2.8 miles, 1.0 mile southeast on road to gate, 0.4 mile southwest on road; 50 feet southeast from road; Sauceda Ranch, Texas USGS 7.5 minute topographic quadrangle; Latitude: 29 degrees, 27 minutes, 12.488 seconds N., Longitude: 103 degrees, 54 minutes, 33.459 seconds W. NAD 83.; UTM coordinates, 605771 m E, 3258723 m N, zone 13.


Soil Moisture: Intermittently moist in some part of the soil moisture control section during July-September. Ustic aridic soil moisture regime

Soil temperature: 64 to 68 degrees F.

Rock fragment surface cover: 45 to 85 percent

Depth to bedrock: 4 to 10 inches

Clay content: 18 to 30 percent

Organic carbon content: less than 2 percent

Calcium carbonate equivalent: less than 5 percent

Rock fragment content: 35 to 80 percent; 25 to 50 percent gravel; 0 to 25 percent cobbles, 0 to 10 percent stones

Reaction class: neutral to moderately alkaline

A horizon
Hue: 7.5YR, 10YR, 2.5Y
Value: 4 to 6 dry, 2 to 4 moist
Chroma: 2 to 4, dry or moist

COMPETING SERIES: These are the Holguin (TX), Sauceda (TX), Scotal (TX) , and Beach (TX) series. Holguin soils contain less than 18 percent clay. Sauceda and Scotal soils contain more than 2 percent organic carbon and more than 5 percent calcium carbonate. Beach soils formed over sandstone and have hues of 2.5YR and 5YR.

GEOGRAPHIC SETTING: Bofecillos soils are on mountains, hills, and plateaus. These soils formed in residuum and colluvium weathered from basalt bedrock. Slopes are 1 to 70 percent. The mean annual precipitation is 12 to 16 inches. The precipitation falls mostly as intense rain during afternoon convective thunderstorms from June through September. The mean annual air temperature is 62 to 67 degrees F. The frost free period is 210 to 250 days and the elevation is 3,500 to 5,500 feet.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Horsetrap (TX), Pantak (AZ) and Ohtwo (TX) soils. Horsetrap soils occur on similar landforms and formed in similar materials, but have a calcic horizon. Pantak soils occur on similar landforms, but formed in residuum and colluvium weathered from igneous rocks, and have an argillic horizon. Ohtwo soils developed in colluvium deposited below escarpments, are very deep, and have a cambic horizon.

DRAINAGE AND PERMEABILITY: Well drained, very high runoff, moderately slow permeability in the surface over very slowly permeable bedrock.

USE AND VEGETATION: This soil is used mainly for livestock grazing and wildlife habitat. Woody plants include creosote bush, mariola, Englemann prickly pear, tasajillo, catclaw acacia, lechuguilla, pitaya, skeletonleaf goldeneye, western honey mesquite, cholla, ocotillo, whitethorn acacia, Torrey yucca, and brownspine prickly pear. Grasses include fluffgrass, bush muhly, chino grama, black grama, sideoats grama, and Arizona cottontop.

DISTRIBUTION AND EXTENT: Southern Desertic Basin, Plains, and Mountains (LRR-D, MLRA 42, Desert Grassland LRU). Areas of basalt and similar igneous rocks of Trans-Pecos Texas. The series is moderately extensive.


SERIES ESTABLISHED: Brewster County, Texas, Main Part, recorrelation 2008. Series name is taken from the Bofecillos Mountains in the southern part of the county.


Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - the zone from 0 to 4 inches (A horizon)

Lithic contact - the boundary at 4 inches (R horizon)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Eleventh Edition, 2010

Revised for the correlation of Hudspeth County, Texas (Main Part) and Culberson County, Texas (Main Part); July, 2012, NMS

Revised for the correlation of Presidio County, Texas ; Oct, 2012, WWJ

National Cooperative Soil Survey