LOCATION MARIASPASS              MT

Tentative Series
REV. EAW-RJS
02/2015

MARIASPASS SERIES

The Mariaspass series consists of shallow, well drained soils that formed in slope alluvium and/or colluvium over residuum derived from shale. These soils are on structural benches and mountain slopes. Slopes are 5 to 60 percent. Mean annual precipitation is about 1,000 mm, and mean annual air temperature is about 3.0 degrees C.

TAXONOMIC CLASS: Loamy, mixed, superactive, nonacid Lithic Cryorthents

TYPICAL PEDON: Mariaspass very parachannery loam, in forest on a 12 percent slope at an elevation of 1,677 meters (colors are for dry soil unless otherwise noted).

Oi--0 to 2 cm; forest litter, slightly decomposed. (0 to 5 cm thick)

E--2 to 10 cm; light olive brown (2.5Y 5/3) very parachannery loam, grayish brown (2.5Y 5/2) moist; weak thin platy structure; soft, very friable, slightly sticky and nonplastic; common very fine, and few medium roots; 45 percent soft shale fragments; many very fine pores; strongly acid (pH 5.4); clear wavy boundary. (5 to 15 cm thick)

C--10 to 38 cm; grayish brown (2.5Y 5/2) extremely parachannery loam, dark grayish brown (2.5Y 4/2) moist; massive; very soft, very friable, slightly sticky and nonplastic; few very fine and common medium roots; 70 percent soft shale fragments; moderately acid (pH 5.6); gradual smooth boundary. (20 to 40 cm thick)

Cr--38 to 48 cm; paralithic shale bedrock, dark gray (2.5Y 4/1) moist, crushing to loam, moderately acid (pH 6.0). (5 to 23 cm thick)

R--48 cm; lithic shale bedrock grading into sandstone.

TYPE LOCATION: Pondera County, Montana; Summit topographic quadrangle; 327567e, 5354066n, NAD 83.

RANGE IN CHARACTERISTICS:

Mean annual soil temperature - 1.5 to 4.5 degrees C.
Depth to paralithic contact - 25 to 48 cm
Depth to lithic contact - 30 to 50 cm

Note: some pedons may have a thin cap of volcanic ash less than 10cm thick.

E horizon
Clay content: 16 to 27 percent
Parafragments: 30 to 70 percent
Reaction: pH 5.1 to 6.4

C horizon
Hue: 5Y to 10YR; dry or moist
Value: 4 to 6 dry; 3 to 5 moist
Chroma: 1 to 3; dry or moist
Texture: sandy loam, sandy clay loam or loam
Clay content: 18 to 35 percent
Parafragments: 30 to 80 percent
Reaction: pH 5.1 to 6.4

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Landform - mountain slopes and structural benches
Slope - 5 to 60 percent
Elevation - 1,425 to 2,300 meters
Parent material - slope alluvium and/or colluvium over residuum derived from shale
Climate - long, cold winters; moist springs; short moist summers
Mean annual precipitation - 750 to 1,550 mm
Mean annual air temperature - 1.0 to 4.0 degrees C.
Frost-free period - 40 to 60 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; slow permeability.

USE AND VEGETATION: Mariaspass soils are used mainly for forest and wildlife habitat. Potential native vegetation is lodgepole pine, subalpine fir, Engelmann spruce, rusty menziesia, alder, beargrass and blue huckleberry. However, areas with steeper slopes may have only scattered vegetation.

DISTRIBUTION AND EXTENT: Mariaspass soils are of small extent in northwest Montana. MLRA 43B.

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

SERIES PROPOSED: Pondera County, Montana, 2015. The Mariaspass series is named for a mountain pass, which divides the Lewis and Clark and the Flathead National Forests.

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

Ochric epipedon - the zone from 0 to 10 cm (Oi and E horizon)
Paralithic contact - at 38 cm (Cr horizon).
Lithic contact - at 48 cm (R horizon).
Particle-size control section - the zone from 25 to 38 cm (part of C horizon)

Marias Pass soils have a cryic temperature regime and an udic moisture regime.

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National Cooperative Soil Survey
U.S.A.