LOCATION SAINT MARIES            ID

Established Series
Rev. SHB/BDG/EMM
07/2013

SAINT MARIES SERIES

The Saint Maries series consists of very deep, well drained soils on mountains. They formed in material weathered from metasedimentary colluvium and residuum, dominantly siltite and fine grained quartzite with an influence of volcanic ash and loess. Permeability is moderate. Slopes range from 35 to 70 percent. The mean annual air temperature is about 43 degrees F and the mean annual precipitation is about 30 inches.

TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Vitrandic Eutrudepts

TYPICAL PEDON: Saint Maries very gravelly ashy silt loam, forest; on a convex northeast-facing slope of 70 percent at 2,700 feet elevation. When described on September 9th, 2002, the soil was dry throughout. (Colors are for dry soil unless otherwise noted.)

Oi--0 to 1 inch; slightly decomposed needles, leaves, twigs, bark, and cones. (1 to 2 inches thick)

Oe--1 to 2 inches; moderately decomposed organic matter mixed with 1980 Mt. St. Helens volcanic ash. (0.5 to 1.5 inches thick)

A--2 to 4 inches; grayish brown (10YR 5/2) very gravelly ashy silt loam; very dark grayish brown (10YR 3/2) moist; weak fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, common medium, and few coarse roots; many very fine and fine tubular pores; 25 percent gravel, 5 percent channers and 5 percent cobbles; neutral (pH 6.8); abrupt wavy boundary. (2 to 5 inches thick)

Bw1--4 to 9 inches; very pale brown (10YR 7/3) very gravelly ashy silt loam, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, common medium, and few coarse roots; many very fine and fine, common medium, and few coarse tubular pores; 30 percent gravel and 5 percent cobbles; slightly acid (pH 6.3); gradual wavy boundary. (4 to 8 inches thick)

Bw2--9 to 22 inches; very pale brown (10YR 7/3) very gravelly ashy loam, brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, common medium, and few coarse roots; many very fine and fine, and few medium and coarse tubular pores; 45 percent gravel and 5 percent cobbles; slightly acid (pH 6.1); clear wavy boundary. (5 to 15 inches thick)

C--22 to 28 inches; pale yellow (2.5Y 7/3) extremely gravelly loam, brown (10YR 5/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; many very fine and fine, and few medium and coarse tubular pores; 55 percent gravel and 10 percent cobbles; slightly acid (pH 6.4); gradual wavy boundary. (5 to 15 inches thick)

C1--28 to 38 inches; pale yellow (2.5Y 7/3) extremely flaggy loam, light yellowish brown (2.5Y 6/3) moist; massive; moderately hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium and coarse roots; many very fine and fine, and few medium and coarse tubular pores; 20 percent gravel, 15 percent channers, 10 percent cobbles, and 25 percent flagstones; slightly acid (pH 6.3); gradual wavy boundary.

C2--38 to 47 inches; pale yellow (2.5Y 7/3) extremely cobbly loam, light yellowish brown (2.5Y 6/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine, and few medium roots; many very fine and fine, and few medium tubular pores; 25 percent gravel, 5 percent channers, and 40 percent cobbles; strongly acid (pH 5.5); gradual wavy boundary.

C3--47 to 60 inches; pale yellow (2.5Y 7/3) extremely cobbly loam, light yellowish brown (2.5Y 6/3) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine, fine and medium roots; many very fine and fine, and few medium tubular and irregular pores; 35 percent gravel and 40 percent cobbles; moderately acid (pH 6.0). (Combined thickness of the C horizon is 30 to 40 inches)

TYPE LOCATION: Benewah County, Idaho; about 4 miles west of St. Maries, ID, about 1,250 feet north and 2,400 feet west of the southeast corner of section 13, T. 46N, R. 3 W., Latitude 47 degrees, 19 minutes, 39.6 seconds N. and Longitude 116 degrees, 39 minutes, 29 seconds W.; USGS Benewah Lake Quadrangle; NAD 83.

RANGE IN CHARACTERISTICS:
(Depth to diagnostic horizons and features are measured from the top of the first mineral layer.)
Mean annual soil temperature - 43 to 46 degrees F
Mean summer soil temperature - 48 to 52 degrees F with an O horizon
Soil moisture - dry for 25 to 45 consecutive days in August to September, moist from mid-September through July
Base Saturation (NH4OAc) in at least one horizon between 10 and 30 inches - 60 to 100 percent

Volcanic ash influence - 7 to 20 inches thick
Volcanic glass content - 5 to 20 percent (estimated)
Acid-oxalate extractable Al+1/2 Fe - 0.4 to 1.0 percent (estimated)
Moist bulk density - 1.0 to 1.2 g/cc (estimated)
Phosphate retention - 25 to 55 percent (estimated)

A horizon
Value - 5 dry and 3 moist
Chroma - 2 dry or moist
Gravel content - 15 to 35 percent
Channer content - 0 to 5 percent
Cobble content - 0 to 10 percent
Total rock fragment content - 15 to 45 percent
Clay content - 5 to 12 percent
Reaction - slightly acid or neutral

Bw horizon
Hue - 10YR or 7.5YR
Value - 5 to 7 dry, 3 or 4 moist
Chroma - 3 or 4, dry or moist
Texture - ashy silt loam, loam in the upper part; silt loam, loam in the lower part
Gravel content - 20 to 45 percent
Cobble content - 5 to 40 percent
Flagstone content - 0 to 5 percent
Total rock fragment content - 30 to 50 percent upper part; 35 to 75 percent lower part
Clay content - 5 to 12 percent
Reaction - slightly acid or neutral

BC horizon
Hue -10YR or 2.5Y
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 3 or 4, dry or moist
Texture - loam or silt loam
Gravel content - 35 to 55 percent
Cobble content - 10 to 35 percent
Flagstone content - 0 to 10 percent
Total rock fragment content - 45 to 85 percent
Clay content - 5 to 12 percent
Reaction - slightly acid or neutral

C horizon
Hue - 2.5Y, 7.5YR or 10YR
Value - 7 or 8 dry, 4 to 6 moist
Chroma - 3 or 4, dry or moist
Texture - loam, silt loam or sandy loam
Gravel content - 20 to 35 percent gravel
Channer content - 0 to 15 percent
Cobble content - 10 to 60 percent
Flagstone content - 0 to 25 percent
Stone content - 0 to 55 percent
Total rock fragment content - 60 to 90 percent
Clay content - 5 to 12 percent
Reaction - strongly acid to slightly acid

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: The Saint Maries soils are on mountains. Slope ranges from 35 to 70 percent. The soils formed in material weathered from metasedimentary colluvium and residuum from the Striped Peak Formation, dominantly siltite and fine grained quartzite, with an influence of volcanic ash and loess. Elevation is 2,200 to 4,400 feet. The climate is characterized by cool moist winters and warm dry summers. The mean annual precipitation is 25 to 35 inches. The mean annual air temperature is 42 to 45 degrees F. The frost-free period is 90 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ardenvoir, Huckle, Lotuspoint, and Dorb soils. Ardenvoir soils are deep and are on south and west-facing side slopes of mountains. Huckle soils have a thick volcanic ash mantle, are deep and are on north-facing side slopes of mountains. Lotuspoint soils are moderately deep and are on south-facing ridges. Dorb soils have more than 35 percent rock fragments in the ash mantle, are deep, and are on north-facing basalt escarpments and canyonsides.

DRAINAGE AND PERMEABILITY: Well drained; high to very high runoff; moderate permeability.

USE AND VEGETATION: These soils are used for timber production, recreation, water supply, and wildlife habitat. Potential natural overstory vegetation is Western redcedar, grand fir, Douglas-fir, and western larch with an understory of queencup beadlily, longtube twinflower, starry false Solomons seal, false Solomons seal, sweetscented bedstraw, and Idaho goldthread.

DISTRIBUTION AND EXTENT: Northern Idaho, U.S.A.; MLRA 43A. The series is not extensive.

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

SERIES ESTABLISHED: Benewah County, Idaho, 2013.

REMARKS: Diagnostic horizons and features recognized in this pedon include:
Ochric epipedon - the zone from 0 to 4 inches (Oi, Oe, and A horizons)
Cambic horizon - the zone from 4 to 22 inches (Bw1 and Bw2 horizons)
Vitrandic feature - the zone from 2 to 22 inches (A, Bw1 and Bw2 horizons)
Particle size control section - the zone from 12 to 42 inches (part of the Bw2, BC, C1 and part of the C2 horizon)

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National Cooperative Soil Survey
U.S.A.