LOCATION GRATWELL CA

Established Series
JBB/CES
09/2021

GRATWELL SERIES

The Gratwell series consists of very deep, well drained soils formed in colluvium and/or slope alluvium over residuum derived from granodiorite and schist. The Gratwell soils are on mountain slopes of the Sierra Nevada Mountains. Slopes range from 3 to 70 percent. The mean annual precipitation is about 1025 mm and the mean annual air temperature is about 10 degrees C.

TAXONOMIC CLASS: Coarse-loamy, isotic, mesic Vitrandic Humixerepts

TYPICAL PEDON: Gratwell fine sandy loam on a southwest facing (220 degree), 50 percent slope under giant sequoia and mixed conifer forest at an elevation of 1756 meters. (Colors are for dry soils unless otherwise noted. When described on May 4, 2015 the soil was moist throughout.)

Oi--0 to 2 cm; dark brown (7.5YR 3/3) slightly decomposed plant material, dark brown (7.5YR 3/2) moist; slightly acid (pH 6.4); abrupt smooth boundary. (1 to 10 cm thick)

Oe--2 to 8 cm; dark brown (7.5YR 3/3) moderately decomposed plant material, dark brown (7.5YR 3/2) moist; common very fine and fine roots throughout; many very fine irregular pores; slightly acid (pH 6.4); abrupt smooth boundary. (0 to 8 cm thick)

A--8 to 16 cm; dark brown (7.5YR 3/2) fine sandy loam, very dark gray (7.5YR 3/1) moist; 5 percent clay; weak fine granular structure; soft, very friable, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; many very fine irregular pores; 5 percent subrounded strongly cemented metasedimentary gravel; NaF pH 10.5; slightly acid (pH 6.4); abrupt wavy boundary. (5 to 25 cm thick)

BA--16 to 42 cm; brown (7.5YR 4/3) gravelly fine sandy loam, brown (7.5YR 5/3) moist; 9 percent clay; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine, fine, medium, and coarse roots throughout; common very fine irregular pores; 15 percent subrounded strongly cemented metasedimentary gravel; NaF pH 10.5; moderately acid (pH 6.0); clear smooth boundary. (0 to 30 cm thick)

Bw1--42 to 81 cm; brown (7.5YR 5/3) gravelly fine sandy loam, dark brown (7.5YR 3/3) moist; 11 percent clay; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky, nonplastic; common fine, medium, and coarse roots throughout; common very fine irregular pores; 20 percent subrounded strongly cemented metasedimentary gravel; NaF pH 11.5; moderately acid (pH 6.0); clear smooth boundary. (15 to 40 cm thick)

Bw2--81 to 108 cm; brown (7.5YR 5/4) very cobbly fine sandy loam, brown (7.5YR 4/3) moist; 10 percent clay; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky, nonplastic; common fine and medium roots throughout; common very fine irregular pores; 30 percent subrounded strongly cemented metasedimentary gravel, 15 percent subrounded strongly cemented metasedimentary cobbles, 5 percent subrounded strongly cemented metasedimentary stones; NaF pH 10.5; moderately acid (pH 5.8); clear smooth boundary. (15 to 45 cm thick)

C--108 to 150 cm; light brown (7.5YR 6/4) extremely stony fine sandy loam, brown (7.5YR 5/4) moist; 7 percent clay; structureless massive; moderately hard, firm, slightly sticky, nonplastic; common fine and medium roots throughout; many very fine interstitial pores; 25 percent subrounded strongly cemented metasedimentary gravel, 20 percent subrounded strongly cemented metasedimentary cobbles, 15 percent subrounded strongly cemented metasedimentary stones; NaF pH 10.5; moderately acid (pH 5.8).

TYPE LOCATION: Tulare County, California, off the Redwood Creek trail in Redwood Canyon of Kings Canyon National Park; USGS 7.5 minute topographic quadrangle: General Grant Grove, California; WGS84 36.682190 latitude and -118.906314 longitude; UTM zone 11 4061310 meters N 329671 meters E NAD83.

RANGE IN CHARACTERISTICS:
Soil temperature: The mean annual soil temperature at 50 cm is 6 to 12 degrees C and the difference between mean summer and mean winter soil temperature is greater than 6 degrees C. The soils have a mesic temperature regime.

Soil moisture: The soils have a xeric soil moisture regime. The soil moisture control section is dry in all parts from about August to October (about 90 days).

Diagnostic Feature(s):
Umbric epipedon thickness: 25 to 75 cm
Cambic horizon thickness: 30 to 100 cm

Organic matter: 2 to 6 percent in the epipedon

Base saturation: less than 50 percent (by ammonium acetate)

Acid-oxalate extractable Al plus 1/2 Fe: 0.4 to 1.0 percent (by weight) to a depth of 100 cm.

Volcanic glass: 5 to 30 percent in the 0.02 to 2.0 mm fraction in an 18 cm thick layer within a depth of 75 cm from the mineral soil surface

Particle size control section weighted average:
Rock fragments: 0 to 35 percent, with 0 to 35 percent gravel, 0 to 15 percent cobbles, and 0 to 10 percent stones.
Clay content: 5 to 15 percent
NaF pH: 9.0 to 11.5

A horizon
Hue: 7.5YR, 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: fine sandy loam, sandy loam, coarse sandy loam, loamy fine sand, loamy sand
Clay content: 3 to 12 percent
Rock fragments: 0 to 35 percent
0 to 35 percent gravel
0 to 5 percent cobbles
Reaction: strongly acid to neutral

BA horizon (where present)
Hue: 7.5YR, 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 or 3, dry or moist
Texture: fine sandy loam, sandy loam, coarse sandy loam
Clay content: 5 to 15 percent
Rock fragments: 0 to 35 percent
0 to 35 percent gravel
0 to 5 percent cobbles
Reaction: strongly acid to neutral

Bw1 horizon
Hue: 7.5YR, 10YR
Value: 4 or 5 dry, 3 moist
Chroma: 3 or 4, dry or moist
Texture: fine sandy loam, sandy loam, loam
Clay content: 2 to 18 percent
Rock fragments: 0 to 60 percent
0 to 35 percent gravel
0 to 35 percent cobbles
0 to 25 percent stones
Reaction: strongly acid to neutral

Bw2 horizon
Hue: 7.5YR, 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 3 or 4, dry or moist
Texture: fine sandy loam, sandy loam, loam
Clay content: 2 to 18 percent
Rock fragments: 0 to 70 percent
0 to 50 percent gravel
0 to 35 percent cobbles
0 to 30 percent stones
Reaction: strongly to slightly acid

C horizon
Hue: 7.5YR, 10YR
Value: 5 to7 dry, 3 to 5 moist
Chroma: 3 to 6, dry or moist
Texture: fine sandy loam, sandy loam, coarse sandy loam, loamy sand loamy fine sand, loamy coarse sand, sand
Clay content: 1 to 18 percent
Rock fragments: 0 to 70 percent
0 to 35 percent gravel
0 to 35 percent cobbles
0 to 25 percent stones
Reaction: very strongly to slightly acid

COMPETING SERIES: These are the Flotag (MLRA 6) soils. Flotag soils are formed in basaltic and andesitic ash and mudflow deposits, have ashy textures and buried horizons, and are moderately well drained.

GEOGRAPHIC SETTING: The Gratwell soils are on broadly concave backslopes of mountain slopes. Slopes range from 3 to 70 percent. These soils formed in colluvium and/or slope alluvium over residuum derived from granodiorite and schist. Elevation is 1385 to 2505 meters. The climate is Mediterranean with warm, dry summers and cool, moist winters. The mean annual precipitation is 885 to 1170 mm and the mean annual air temperature is 7 to 13 degrees C. The frost-free season is 105 to 200 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Sherman soils. The Sherman soils are on concave stream terraces and footslopes of drainageways on mountain slopes and are moderately well drained.

DRAINAGE AND PERMEABILITY: Well drained, moderately high to high saturated hydraulic conductivity.

USE AND VEGETATION: This soil is used for recreation, wildlife habitat, and watershed. Vegetation is giant sequoia, white fir, sugar pine, incense cedar, and California dogwood.

DISTRIBUTION AND EXTENT: Sierra Nevada Mountains of California; MLRA 22A. These soils are of limited extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Davis, California

SERIES PROPOSED: Tulare County, California in Sequoia and Kings Canyon National Parks. Source of name is coined.

REMARKS:
Particle Size Control Section for this pedon: 33 to 108 cm
Diagnostic horizons and features recognized in this pedon are:
Umbric Epipedon 8 to 42 cm
Cambic Horizon 42 to 108 cm

ADDITIONAL DATA:
NASIS User Pedon ID: 2015CA7925014

Soil classified using the 12th Edition of the Keys to Soil Taxonomy.

National Cooperative Soil Survey
U.S.A.