LOCATION JAZZBO MT

Established Series
Rev. PHO/DJP/BDM
08/2026

JAZZBO SERIES

The Jazzbo series consists of very deep, well drained soils formed in alluvium, colluvium or glaciofluvial deposits from mixed metasedimentary rock. These soils occur on alluvial fans, stream terraces, escarpments, hills and mountain slopes. Slopes are 0 to 70 percent. Mean annual precipitation is about 450 mm and mean annual air temperature is about 7.0 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Haploxeralfs

TYPICAL PEDON: Jazzbo gravelly loam, in coniferous forest. This profile was described on an 2 percent slope at 1,023 meters elevation. (Colors are for dry soil unless otherwise noted.)

A--0 to 9 cm; dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; weak fine granular structure; slightly hard, friable, moderately sticky and very plastic; many very fine and common fine roots; common very fine irregular pores; slightly acid (pH 6.2); clear smooth boundary.

Bt1--9 to 37 cm; brown (7.5YR 5/3) very gravelly sandy clay loam, brown (7.5YR 4/3) moist; moderate medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; many very fine, common fine and few medium roots; many very fine and few fine irregular pores; slightly acid (pH 6.2); clear wavy boundary.

Bt2--37 to 60 cm; pinkish gray (7.5YR 6/2) very gravelly sandy clay loam, brown (7.5YR 5/2) moist; moderate medium subangular structure; hard, firm, very sticky and very plastic; common very fine and few fine roots; common very fine and fine irregular pores; neutral acid (pH 6.6); clear wavy boundary.

BC1--60 to 115 cm; pink (7.5YR 7/3) extremely gravelly sandy clay loam, brown (7.5YR 5/3) moist; massive; loose, nonsticky and nonplastic; few very fine roots; common very fine interstitial pores; neutral (pH 6.8).

BC2--115 to 152 cm; pink (7.5YR 7/3) extremely gravelly sandy loam, brown (7.5YR 5/3) moist; massive; loose, nonsticky and nonplastic; few very fine roots; common very fine interstitial pores; neutral (pH 6.8).

TYPE LOCATION: Mineral County, Montana; approximately 112 meters north and 430 meters east of the SW corner of Sec. 36, T. 15 N., R. 25 W.; Tarkio topographic quadrangle; latitude 47.0079870; longitude - 114.7070750, datum WGS 84.

RANGE IN CHARACTERISTICS:

Mean annual soil temperature: 5.0 to 7.0 degrees C.
Depth to argillic horizon - 2 to 12 cm.
Particle-size control section - averages 20 to 34 percent clay.

Oi horizon (when present)
Thickness: 1 to 10 cm

A horizon
Hue: 10YR or 7.5YR
Value: 4 to 7 dry; 2 to 5 moist
Chroma: 1 to 4 dry or moist
Texture, less than 2mm fraction: loam, sandy loam or sandy clay loam
Clay content: 12 to 25 percent
Rock fragments: 0 to 34 percent--0 to 34 percent gravel; 0 to 10 percent cobbles; 0 to 20 percent stones
Reaction: pH 5.8 to 7.3
Thickness: 3 to 12 cm thick

Bt horizon(s)
Hue: 10YR or 7.5YR
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 2 to 6 dry or moist
Texture, less than 2mm fraction: loam or sandy clay loam
Clay content: 20 to 34 percent
Rock fragments: 35 to 70 percent--35 to 70 percent gravel; 0 to 35 percent cobbles; 0 to 20 percent stones
Reaction: pH 5.8 to 7.3
Thickness: 10 to 45 cm thick (Bt1) and 15 to 40 cm thick (Bt2)

BC horizon(s)
Hue: 10YR, 7.5YR or 2.5Y
Value: 5 to 7 dry; 4 to 6 moist
Chroma: 1 to 4 dry or moist
Texture, less than 2mm fraction: sandy clay loam, sandy loam or loamy sand
Clay content: 10 to 25 percent
Rock fragments: 40 to 75 percent--40 to 75 percent gravel; 0 to 35 percent cobbles; 0 to 25 percent stones
Reaction: pH 6.0 to 7.5
Thickness: 55 to 115 cm thick

COMPETING SERIES: None listed.

GEOGRAPHIC SETTING:
Landform - stream terraces, escarpments, alluvial fans, hills and mountain slopes.
Elevation - 760 to 1100 meters.
Slope - 0 to 70 percent.
Parent material - alluvium, colluvium or glaciofluvial deposits derived from metasedimentary rock.
Climate - long, cold winters; moist springs; short warm summers.
Mean annual precipitation - 381 to 538 mm.
Mean annual air temperature - 5.0 to 7.0 degrees C.
Frost-free period - 70 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: Jazzbo soils are associated with Bricker, Tamely and Yellowbay soils.

DRAINAGE AND PERMEABILITY: Well drained; moderate permeability (1 to 10 um/s).

USE AND VEGETATION: Jazzbo soils are used mainly for recreation, timber production and wildlife habitat. The vegetation is ponderosa pine and Douglas-fir with bluebunch wheatgrass, arrowleaf balsamroot, lupine, Oregon grape, pine grass, and kinnikinnick in the understory.

DISTRIBUTION AND EXTENT: Jazzbo soils are of moderate extent in northwestern Montana. MLRA 43A and 44A.

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

SERIES PROPOSED: Lolo National Forest area in Mineral County, Montana, 2026.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 9 cm (A horizon)
Argillic horizon - from 9 to 60 cm (Bt1 and Bt2 horizons)

Jazzbo soils have a frigid temperature regime and a xeric moisture regime.

Taxonomic version: Thirteenth Edition, 2022

National Cooperative Soil Survey
U.S.A.