LOCATION MACK                    CO+AZ NM UT

Established Series
Rev. AJC/DKR/CRP/JCK
12/2017

MACK SERIES

The Mack series consists of very deep, well drained soils that formed in slope alluvium and alluvium derived from sandstone and shale. Mack soils are on fan remnants, alluvial fans, stream terraces and mesas. Slopes are 0 to 12 percent. Mean annual precipitation is about 203 mm, and mean annual air temperature is about 11 degrees C.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Typic Calciargids

TYPICAL PEDON: Mack loam in cropland. (Colors are for dry soil unless otherwise noted).

Ap--0 to 15 cm; light yellowish brown (10YR 6/4) loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; common very fine and fine tubular pores; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary. (10 to 20 cm thick)

Btk1--15 to 36 cm; light brown (7.5YR 6/4) clay loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine roots throughout and between peds; common very fine and fine tubular pores; common distinct clay films on faces of peds and few faint clay films on surfaces along pores; few fine and medium irregular calcium carbonate masses in the matrix; strongly effervescent; moderately alkaline (pH 8.2); clear smooth boundary.

Btk2--36 to 51 cm; light brown (7.5YR 6/4) clay loam, brown (7.5YR 4/4) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few fine roots throughout and between peds; common very fine and fine tubular pores; common distinct clay films on faces of peds; common fine irregular calcium carbonate masses in the matrix; violently effervescent; moderately alkaline (pH 8.4); clear smooth boundary.

Btk3--51 to 127 cm; pink (7.5YR 8/4) gravelly clay loam, reddish yellow (7.5YR 6/6) moist; massive; soft, very friable, slightly sticky and slightly plastic; few very fine and fine tubular pores; common faint clay films on faces of peds; common fine and medium irregular calcium carbonate masses in the matrix and few distinct carbonate coats on rock fragments; 15 percent gravel; violently effervescent; strongly alkaline (pH 8.5); clear smooth boundary. (combined thickness of Btk horizons is 90 to 150 cm)

Bk--127 to 203 cm; pink (7.5YR 7/4) gravelly clay loam, light brown (7.5YR 6/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine tubular pores; few fine and medium irregular calcium carbonate masses in the matrix and few distinct carbonate coats on rock fragments; 20 percent gravel; violently effervescent; moderately alkaline (pH 8.4).

TYPE LOCATION: Mesa County, Colorado; about 201 meters south and 46 meters west of the northeast corner of sec. 27, T 9 S., R 103 W; USGS Highline Lake, Colorado topographic quad, NAD 27; UTM 83850 meters E, 46650 meters N, zone 12.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 11 to 14 degrees C
Particle-size control section (weighted average):
Clay content - 25 to 35 percent
Rock fragments - 0 to 25 percent
Depth to base of argillic - 100 to 150 cm

A or Ap horizon
Hue: 7.5YR, 10YR or 2.5Y
Value: 4, 5, 6 or 7 dry; 3, 4 or 5 moist
Chroma: 2, 3, 4 or 6 dry or moist
Texture: fine sandy loam, clay loam, or loam
Clay content: 15 to 30 percent
Rock fragments: 0 to 15 percent gravel
Reaction: 7.6 to 8.2

Btk1 horizon
Hue: 7.5YR or 10YR
Value: 4, 5, or 6 dry; 3 or 4 moist
Chroma: 2, 3, 4 dry; 3 or 4 moist
Texture: clay loam or sandy clay loam
Clay content: 25 to 35 percent
Rock fragments: 0 to 25 percent
Calcium carbonate equivalent: 5 to 15 percent
Gypsum content: 0 to 4 percent
Sodium adsorption ratio: 0 to 4
Reaction: 8.0 to 8.4

Btk2 and Btk3 horizon:
Hue: 7.5YR or 10YR
Value: 4, 5 or 6 dry; 3 or 4 moist
Chroma: 2, 3, 4 dry; 3 or 4 moist
Texture: clay loam or sandy clay loam
Clay content: 25 to 35 percent
Fragments: 0 to 25 percent
Calcium carbonate equivalent: 15 to 40 percent
Gypsum content: 0 to 4 percent
Sodium adsorption ratio: 0 to 10
Reaction: 8.0 to 8.8

Bk horizon
Hue: 7.5YR to 10YR
Value: 5, 6, 7 or 8 dry; 4, 5, 6, or 7 moist
Chroma: 2, 3, 4 dry; 3 or 4 moist
Texture: clay loam, sandy clay loam or sandy loam
Clay content: 18 to 35 percent
Rock fragments: 0 to 25 percent
Calcium carbonate equivalent: 15 to 40 percent
Gypsum content: 0 to 4 percent
Sodium adsorption ratio: 0 to 10
Reaction: 8.0 to 8.8

Some pedons have a Bt above the Btk horizon.
Some pedons have a BCk horizon.

COMPETING SERIES:
Cataract (UT) - are moderately deep to a lithic contact
Chattin (ID) - have a lithologic discontinuity; have volcanic glass
Grieta (NM) - have an argillic base less than 100 cm deep; have less than 18 percent clay in the lower part of the subsoil
Mesa (CO) - have more than 35 percent rock fragments in the lower part of the subsoil
Nannyton (ID) - have a lithologic discontinuity; have less than 18 percent clay in the lower part of the subsoil
Neiberger (CO) - are moderately deep to a paralithic contact

GEOGRAPHIC SETTING:
Landform - fan remnants, alluvial fans, stream terraces, and mesas
Elevation - 1,372 to 1.768 meters
Slope - 0 to 12 percent
Parent material - slope alluvium or alluvium derived from sandstone and shale
Mean annual temperature - 10.0 to 12.8 degrees C
Mean annual precipitation - 152 to 229 mm
Precipitation pattern - significant increases in spring, late summer and early fall
Frost-free period - 140 to 180 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fruita and Mesa soils.

DRAINAGE AND PERMEABILITY: Well drained; moderate and moderately slow permeability

USE AND VEGETATION: Mack soils are used for native pasture and irrigated cropland. Native vegetation is Indian ricegrass, shadscale saltbush, winterfat, James' galleta, and squirreltail.

DISTRIBUTION AND EXTENT: Mack soils are of moderate extent in southwestern Colorado, southeastern Utah, northwestern New Mexico, and northeastern Arizona. MLRA 34B and 35.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Mesa County, (Grand Junction Area), Colorado. 1948.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon from - 0 to 15 cm (Ap horizon)
Argillic horizon from - 15 to 127 cm (Btk1, Btk2, and Btk3 horizons)
Calcic horizon from - 36 to 203 cm (Btk2, Btk3, and Bk horizons)
Particle size control section from - 15 to 65 cm (Btk1, Btk2 and part of Btk3 horizon)

Mack soils have a mesic soil temperature regime and an aridic soil moisture regime.

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National Cooperative Soil Survey
U.S.A.