LOCATION MCCUMBERSON AK
Established Series
Rev. MHC/DLM
05/2022
MCCUMBERSON SERIES
Depth class: very deep
Drainage class: well drained
Landforms: till plains
Parent material: silty eolian deposits over gravelly till
Elevation: 2,782 to 3,442 feet (848 to 1,049 m)
Slope: 2 to 12 percent
Annual precipitation: 30 to 35 inches (712 to 894 mm)
Annual temperature: 25 degrees F (-4 degrees C)
Frost-free period: 50 to 70 days
TAXONOMIC CLASS:
TYPICAL PEDON: McCumberson silt loam - on a slope of 6 percent under shrub birch-dwarf ericaceous mosaic. (All colors are for moist soil)
Oi--0 to 4 inches (0 to 10 cm); dark reddish brown (5YR 3/4) slightly decomposed plant material; many very fine, fine, medium, and coarse roots; extremely acid (pH 4.4); clear smooth boundary.
Oe--4 to 7 inches (10 to 18 cm); dark reddish brown (5YR 2.5/2) moderately decomposed plant material; many very fine, fine, many medium, and coarse roots; extremely acid (pH 4.4); clear smooth boundary.
A--7 to 9 inches (18 to 23 cm); very dark grayish brown (10YR 3/2) silt loam; moderate medium platy structure; very friable, nonsticky and nonplastic; many very fine, fine, medium, and coarse roots; very strongly acid (pH 4.7); abrupt smooth boundary.
E--9 to 12 inches (23 to 30 cm); dark grayish brown (10YR 4/2) and very dark grayish brown (10YR 3/2) silt loam; weak medium granular structure; very friable, nonsticky and nonplastic; few very fine and fine roots; very strongly acid (pH 4.7); abrupt smooth boundary.
Bs--12 to 15 inches (30 to 38 cm); strong brown (7.5YR 4/6) silt loam; weak coarse subangular blocky structure; very friable, nonsticky and nonplastic; few very fine and fine roots; 2 percent gravel; strongly acid (pH 5.4); abrupt wavy boundary.
Eb--15 to 16 inches (38 to 41 cm); dark grayish brown (10YR 4/2) silt loam; weak coarse subangular blocky structure; very friable, nonsticky and nonplastic; few very fine and fine roots; 2 percent gravel; strongly acid (pH 5.4); abrupt wavy boundary.
2Bsb--16 to 19 inches (41 to 48 cm); strong brown (7.5YR 4/6) very cobbly sandy loam; massive; friable, nonsticky and nonplastic; few very fine and fine roots; 20 percent gravel, 20 percent cobbles; strongly acid (pH 5.5); gradual wavy boundary.
2BC--19 to 32 inches (48 to 81 cm); dark yellowish brown (10YR 4/4) very cobbly sandy loam; massive; friable, nonsticky and nonplastic; 20 percent gravel, 20 percent cobbles; strongly acid (pH 5.5); gradual wavy boundary.
2C--32 to 60 inches (81 to 152 cm); very dark grayish brown (10YR 3/2) very cobbly sandy loam; massive; friable, nonsticky and nonplastic; 20 percent gravel, 20 percent cobbles; strongly acid (pH 5.5)
TYPE LOCATION: Delta River Area, Alaska; along the upper Delta River about 0.75 miles east of Juneau Falls; UTM coordinates: Zone 6, Easting 553893, Northing 7005886.
RANGE IN CHARACTERISTICS:
Soil moisture class: udic
Average annual soil temperature: 30 to 28 degrees F (-1 to -2.0 degrees C)
Mean summer soil temperature: 36 to 39 degrees F. (2 to 4 degrees C)
Depth to strongly contrasting textural stratification: 9 to 19 inches (22 to 48 cm)
Oi, Oe horizon:
Color-hue of 5YR or 10YR; value of 2.5 or 3; chroma of 2 to 4
Textureslightly decomposed organic material or moderately decomposed organic material
Organic matter content65 to 90 percent
Reactionultra acid to very strongly acid
A horizon:
Color-value of 2 or 3; chroma of 2 or 3
Clay content0 to 10 percent
Silt content55 to 75 percent
Sand content15 to 35 percent
Organic matter content4 to 8 percent
Rock fragments0 to 2 percent subangular strongly cemented gravel
Reactionextremely acid to strongly acid
E or Eb horizon:
Color-chromavalue of 4 or 5
Clay content0 to 10 percent
Silt content55 to 75 percent
Sand content15 to 35 percent
Organic matter content4 to 8 percent
Rock fragments0 to 2 percent subangular strongly cemented gravel
Reactionextremely acid to strongly acid
Bs horizon:
Color-hue of 2.5YR or 7.5YR; value of 4 or 5; chroma of 4 to 8
Textureloam or silt loam
Clay content0 to 10 percent
Silt content45 to 75 percent
Sand content15 to 35 percent
Organic matter content2 to 4 percent
Rock fragments0 to 2 percent subangular strongly cemented gravel; 0 to 2 percent subangular strongly cemented cobbles
Reactionvery strongly acid to strongly acid
2Bsb horizon:
Color-hue of 2.5YR to 7.5YR; value of 4 or 5; chroma of 4 to 8
Texturevery cobbly sandy loam, very gravelly loam or very gravelly sandy loam
Clay content5 to 15 percent
Silt content10 to 45 percent
Sand content45 to 75 percent
Rock fragments15 to 30 percent subangular strongly cemented gravel; 5 to 20 percent subangular strongly cemented cobbles
Reactionstrongly acid to moderately acid
2BC horizon:
Color-hue of 10YR or 2.5Y; value of 3 or 4; chroma of 2 or 3
Texturevery cobbly sandy loam, very gravelly loam or very gravelly sandy loam
Clay content5 to 15 percent
Silt content10 to 45 percent
Sand content45 to 75 percent
Rock fragments15 to 30 percent subangular strongly cemented gravel; 5 to 20 percent subangular strongly cemented cobbles
Reactionstrongly acid to moderately acid
2C horizon:
Color-hue of 10YR or 2.5Y; value of 3 or 4; chroma of 2 or 3
Texturevery cobbly sandy loam, very gravelly loam or very gravelly sandy loam
Clay content5 to 15 percent
Silt content10 to 45 percent
Sand content45 to 75 percent
Rock fragments15 to 30 percent subangular strongly cemented gravel; 5 to 20 percent subangular strongly cemented cobbles
Reactionstrongly acid to moderately acid
COMPETING SERIES: These are the no competing series in this classification.
GEOGRAPHIC SETTING:
Landforms: till plains
Parent material: silty eolian deposits over gravelly till
Elevation: 2,782 to 3,442 feet (848 to 1,049 m)
Slope: 2 to 12 percent
Annual precipitation: 30 to 35 inches (712 to 894 mm)
Annual temperature: 25 degrees F (-4 degrees C)
Frost-free period: 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: These include
Basaltlake,
Frostcircle, and
Phelanna soils. Basaltlake soils are well drained, very deep, and occur on mountains. Frostcircle soils are poorly drained, very shallow or shallow to permafrost, and occur on mountains. Phelanna soils are poorly drained, very deep, and occur on mountains.
DRAINAGE AND PERMEABILITY: Well drained, medium runoff. Saturated hydraulic conductivity is moderately high to high.
USE AND VEGETATION: Used for wildlife habitat and recreation. Native vegetation is shrub birch-dwarf ericaceous mosaic.
DISTRIBUTION AND EXTENT: MLRA 228, Interior Alaska Mountains, Alaska. The series is of small extent.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA
SERIES ESTABLISHED: Delta River Area, Alaska, 2005
REMARKS: Diagnostic features and horizons recognized in this profile include:
Ochric horizons: 9 to 12 inches and 15 to 16 inches. (E and Eb horizons)
Spodic horizons: 12 to 15 inches and 16 to 19 inches. (Bs and 2Bsb horizons)
Lithologic discontinuity: At the upper boundary of Bs horizon
Loamy-skeletal weighted average particle size control section: 10 to 40 inches below the mineral soil surface
Temperature regime: cryic
ADDITIONAL DATA:
National Cooperative Soil Survey
U.S.A.