LOCATION FRONTON            NM
Established Series
Rev. JJF/VGL
12/2003

FRONTON SERIES


These soils have light brown gravelly loam A horizons, light reddish brown to reddish brown gravelly clay B horizons grading to weathered shale and interbedded sandstone at depths typically less than 20 inches.

TAXONOMIC CLASS: Clayey, mixed, active, mesic, shallow Ustic Haplargids

TYPICAL PEDON: Fronton gravelly loam - rangeland (Colors are for dry conditions unless otherwise noted).

A1--0 to 3 inches; light brown (7.5YR 6/4) gravelly loam; dark brown (7.5YR 3/4) moist; weak fine grandular structure; soft, very friable, nonsticky; abundant very fine and fine roots; many very fine and fine interstitial pores; 75 percent of the surface is covered with quartz gravel and the horizon contains about 35 percent quartz gravel; neutral; clear smooth boundary. 3 to 6 inches thick.

B1--3 to 7 inches; reddish brown (5YR 5/4) gravelly clay; reddish brown (5YR 4/4) moist; moderate very fine subangular blocky structure; hard, firm, sticky; abundant very fine and fine roots; common very fine tubular pores; a few vertical and horizontal ped surfaces are smooth and these appear to be clay films; about 35 percent quartz gravel; neutral; clear smooth boundary. 3 to 6 inches thick.

B2t--7 to 11 inches; light reddish brown (5YR 6/3) gravelly clay; reddish brown (5YR 5/3) moist; strong medium and coarse subangular blocky structure; very hard firm, sticky; plentiful very fine and fine roots mostly between peds; few penetrating the peds; few fine interstitial pores and few very fine tubular pores within the peds; continuous thin clay films on surface of peds; about 35 percent quartz gravel; neutral; clear smooth boundary. 4 to 8 inches thick.

B3ca--11 to 16 inches; pinkish gray (5YR 6/2) gravelly heavy clay loam; dark reddish gray (5YR 4/2) moist; moderate medium and coarse subangular blocky structure; hard, firm, slightly sticky; few very fine roots; few very fine tubular pores within the peds; common thin clay films on surfaces of peds; calcareous, lime disseminated and as small soft masses and thin streaks; few scattered small; salt crystals; about 25 percent quartz gravel; moderately alkaline; gradual irregular boundary. 3 to 7 inches thick.

C--16 to 40 inches +; partially weathered soft grayish shale and interbedded sandstone; becomes less weathered with depth, strongly calcareous structure is essentially that of the shale bedding.

TYPE LOCATION: Sandoval County, New Mexico, NE1/4 of section 14, T19N., R1W. Along highway 44 southwest of the town of Cuba along road cut where this highway passes through the NW section corner. This road cut also shows most of the range of characteristics.

RANGE IN CHARACTERISTICS: Thickness of the solum typically ranges from 13 to 20 inches but can range to near 30 inches. Depth to weathered shale bedrock is typically 20 inches or less but occasionally the shale has been altered to the extent that original rock structure has been altered sufficiently to make it difficult to identify to a depth of about 40 inches. Depth to calcareous material ranges from 8 to 18 inches. The ca horizon is not pronounced and the calcium carbonate equivalent does not exceed 15 percent. Quartz gravel content of the solum ranges from 20 to 50 percent with an occasional cobble while the surface gravel cover ranges from 50 to 90 percent. Reaction of the solum ranges from neutral in the upper part to moderately alkaline in the lower part. Color of the A horizon ranges in hue from 10YR to 7.5YR, in chroma from 2 through 4 and in value from 5 through 6 dry and 3 through 4 moist. A horizons with values of 5 dry and 3 moist must be less than 1/3 as thick as the solum. Color of the B horizon ranges in hue from 7.5YR to slightly reddish than 5YR, in chroma from 2 through 4, and in value from 5 through 7 dry and 4 through 6 moist.

Texture of the B horizon is typically a gravelly clay but ranges to a gravelly heavy clay loam. Structure of the B2t horizon ranges from strong to moderate and often includes some peds that are angular blocky. The shale bedrock typically includes thin strata of sandstone ranging from soft to hard.

COMPETING SERIES: These include Cuates, Malaposa, Hassell, Hondo, Fernando and Renohill soils in the same family. The Cuates soils are typically less red in hue and are nongravelly. The Malaposa soils are derived from basic igneous material high in basalt gravel over shale and interbedded sandstone. The Hassell soils are nongravelly. The Hondo and Fernando soils are nongravelly, have a strong lime zone typically within 30 inches of the surface and have no shale to depths greater than 40 inches. The Renohill soils are of yellower hues in the B horizon and are nongravelly.

GEOGRAPHIC SETTING: The Fronton soils occur on gently sloping to steep dissected fans and mountain foot-slopes. The regolith consists of gravelly sediments derived principally from acid igneous formations that now overly shale and interbedded sandstone. The gravels are well rounded and composed mainly of quartz. The climate is continental. At the type location the average annual precipitation is about 15 inches. The average annual temperature (air) is about 50 degrees F. and the average summer temperature (air) is about 65 degrees F. The Thornthwaite P-E Index is ranges from about 20 to 40.

GEOGRAPHICALLY ASSOCIATED SOILS: Fronton soils occur in association with the Persayo, Chipeta, Travessilla, and Las Lucas soils. Persayo and Chipeta soils are shallower to shale. Travessilla soils are shallow to sandstone. Las Lucas soils have clay loam control section textures and lack an argillic horizon.

DRAINAGE AND PERMEABILITY: Well drained; runoff is medium to rapid and permeability is slow.

USE AND VEGETATION: Principal use is rangeland but the soil is also used as a source of gravel. Vegetation consists of scattered pinon, juniper, and some ponderosa pine with an understory of sage, blue grama, sacatone grass and sand dropseed.

DISTRIBUTION AND EXTENT: Present known distribution is limited to north central and northwestern New Mexico where it is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: The Rio Puerco Reconnaissance Survey, SCS -NM-2, 1940.

REMARKS: The Fronton soils were formerly classified in the Brown soil group. The Fronton series has been in the past classified as a Typic Haplargid but it is believed that with present criteria of the Soil Classification system it may be more appropriate in the subgroup Mollic Haplargid.

The family minerology designation is also tentative as at present it has not been established that mixed is any more appropriate than montmorillonitic.

OSED scanned by SSQA. Last revised by state on 10/65.

In October 2000, taxonomic classification was converted to the closest match found in Soil Taxonomy, Second Edition 1999. No update was made to horizon nomenclature, competing series section, etc. Other placements may be more appropriate after a complete update.


National Cooperative Soil Survey
U.S.A.