LOCATION BAMAC                   NM+UT

Established Series
Rev. CB/CDL/LWH/SAZ/
08/2017

BAMAC SERIES

The Bamac series consists of very deep, excessively drained, very rapidly permeable soils formed in alluvium and slope alluvium derived from conglomerate and sandstone. Bamac soils are on fan terraces, fan remnants, hills, and ridges. Slopes range from 1 to 65 percent. Mean annual precipitation is about 13 inches and the mean annual air temperature is about 51 degrees F.

TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Aridic Ustorthents

TYPICAL PEDON: Bamac very gravelly loamy sand - rangeland. (Colors are for dry soils unless otherwise noted.)

A--0 to 4 inches; light yellowish brown (10YR 6/4) very gravelly loamy sand, dark yellowish brown (10YR 4/4) moist; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; common fine and common medium roots; 55 percent gravel; slightly effervescent; moderately alkaline; clear smooth boundary. (2 to 5 inches thick)

C1--4 to 10 inches; light yellowish brown (10YR 6/4) loamy sand, brown (10YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common medium roots; 10 percent gravel; slightly effervescent; moderately alkaline; clear wavy boundary. (0 to 6 inches thick)

C2--10 to 21 inches; very pale brown (10YR 7/3) very gravelly loamy coarse sand, brown (10YR 5/3) moist; massive; soft, very friable, nonsticky and nonplastic; few fine roots; 45 percent gravel; slightly effervescent; moderately alkaline; gradual wavy boundary. (8 to 15 inches thick)

C3--21 to 37 inches; pale brown (10YR 6/3) very gravelly loamy coarse sand, brown (10YR 4/3) moist; massive; soft, very friable, nonsticky and nonplastic; 55 percent gravel; slightly effervescent; moderately alkaline (pH 8.2); gradual wavy boundary. (13 to 17 inches thick)

C4--37 to 65 inches; pink (7.5YR 7/4) very gravelly loamy coarse sand, yellowish brown (10YR 5/4) moist; massive; soft, very friable, nonsticky and nonplastic; 50 percent gravel; slightly effervescent; moderately alkaline.

TYPE LOCATION: Sandoval County, New Mexico; about 2.5 miles south west of Cochiti Pueblo; 2,550 feet east and 100 feet south of the northeast corner of section 26, T.16N., R.5E.

RANGE IN CHARACTERISTICS: Soil Moisture: Continuously moist, in most years, in some part of the soil moisture control section November through April and intermittently moist July through October. The soil is driest during May and June. Aridic ustic soil moisture regime.

Clay content: 0 to 10 percent

Rock fragments: 35 to 55 percent gravel, 0 to 5 percent cobbles

Reaction: slightly alkaline to moderately alkaline

Soil Temperature: 49 to 55 degrees F.

A horizon
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 or 4, dry or moist
Texture: loamy sand, sandy loam, loamy fine sand

C horizon
Hue: 7.5YR, 10YR, 2.5Y
Value: 3 to 8 dry, 4 to 6 moist
Chroma: 3 to 6 moist or dry
Rock Fragments: 10 to 80 percent total; 0 to 70 percent gravel and 0 to 60 percent cobbles
Texture: coarse sand, loamy sand. Some pedons have thin strata of coarse sand, loamy sand, or sandy loam.

Some pedons have Ck horizons

COMPETING SERIES: These are the Barkerville (AZ) and Schamber (SD) series. The Schamber soil is in LRR-G and is moist in the soil moisture control section during May and June. Barkerville soils are moderately deep.

GEOGRAPHIC SETTING: The Bamac soils formed in alluvium and slope alluvium derived from conglomerate and sandstone on fan remnants, fan terraces, hills, and ridges. Slopes range from 1 to 65 percent. Elevation ranges from 5,190 to 6,900 feet. Mean annual precipitation is 12 to 17 inches; mean annual air temperature is 46 to 53 degrees F. The frost-free period is 110 to 160 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Espiritu soils, Royosa, and Waumac soils. The Espiritu soils have argillic horizons. Royosa soils are Ustipsamments and Waumac soils are coarse-loamy.

DRAINAGE AND PERMEABILITY: Excessively drained; low to medium runoff; very rapid permeable.

USE AND VEGETATION: Bamac soils are used for livestock grazing. Principal vegetation is blue grama, black grama, needleandthread, and sideoats grama, with scattered oneseed juniper and pinyon pine.

DISTRIBUTION AND EXTENT: North central New Mexico and southern Utah. MLRA 35 and 36. LRR-D. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona

SERIES ESTABLISHED: Sandoval County, New Mexico, 1987

REMARKS: Diagnostic horizons and features recognized in this pedon are:

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

Entisol Feature - the lack of diagnostic horizons (C1, C2, C3, C4 horizons)

Classified according to Soil Taxonomy, Second Edition, 1999; Keys to Soil Taxonomy, Tenth Edition, 2006.

Update and revisions for the correlation of Natural Bridges National Monument
4 Dec 2008 CEM
Update and revisions for the correlation of Kane County, UT, July 2017 CEM

---

National Cooperative Soil Survey
U.S.A.