LOCATION LAKETWIN CA
Established Series
Rev. BAL/JPS/ET
10/2016
LAKETWIN SERIES
The Laketwin series consists of very deep, well drained soils formed in residuum and colluvium derived from metamorphic rocks. These soils are on mountains and have slopes of 9 to 50 percent. Mean annual precipitation is 2540 millimeters (100 inches) and the mean annual temperature is 7 degrees C (44 degrees F).
TAXONOMIC CLASS: Loamy-skeletal over fragmental, mixed, superactive, frigid Pachic Humixerepts
TYPICAL PEDON: Laketwin very fine sandy loam under a stand of white fir, grand fir, Douglas-fir, and snowberry. When described on August 27, 2004, the soil was dry throughout. (Colors are for dry soil unless otherwise stated).
Oi--0 to 2 centimeters (0 to 1 inch); slightly decomposed plant material consisting of needles and leaves; abrupt smooth boundary; moderately acid (pH 6.0). (0 to 20 centimeters thick)
A1--2 to 7 centimeters (1 to 3 inches); dark grayish brown (10YR 4/2) loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky parting to weak very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots throughout; many very fine and fine, and common medium tubular pores; 5 percent gravel; strongly acid (pH 5.2); abrupt smooth boundary.
A2--7 to 22 centimeters (3 to 9 inches); dark grayish brown (10YR 4/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots throughout; many very fine and fine, and common medium and coarse tubular pores; 25 percent gravel; very strongly acid (pH 5.0); clear wavy boundary. (Combined thickness of A horizons is 20 to 30 centimeters thick)
AB--22 to 58 centimeters (9 to 23 inches); brown (10YR 5/3), gravelly loam dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots throughout; many very fine and common fine, medium and coarse tubular pores; 20 percent fine spherical strongly cemented iron-manganese nodules in matrix; 20 percent gravel, 5 percent cobbles; very strongly acid (pH 4.6); clear wavy boundary. (30 to 50 centimeters)
Bw--58 to 82 centimeters (23 to 32 inches); brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine and fine roots throughout; many fine and common medium tubular pores; 20 percent fine spherical strongly cemented iron-manganese nodules in matrix; 10 percent gravel, 30 percent cobbles; very strongly acid (pH 4.8); abrupt smooth boundary. (20 to 50 centimeters thick)
2C--82 to 200 centimeters (32 to 79 inches); channers; strongly cemented schist, fractures 2 to 10 centimeters apart; few fine roots; very strongly acid (pH4.8).
TYPE LOCATION: Humboldt County, California; USGS Mad River Buttes topographic quadrangle; WGS84 Decimal degrees 40.7442222latitude and
-123.7631389 longitude; UTM Zone 10, 435584mE, 4510624mN, NAD 83.
RANGE IN CHARACTERISTICS:
Soil Depth: Depth to highly fractured schist is 50 to 90 centimeters (20 to 35 inches).
Soil moisture: The soil moisture control section is dry from July 1st to October 15th and moist in all parts from November 15 to June 1st. This soil has a xeric soil moisture regime.
Soil temperature: The mean annual soil temperature is 5 to 7 degrees C (41 to 45 degrees F). The difference between the mean summer and mean winter temperature is greater than 6 degrees C. This soil has a frigid soil temperature regime.
The umbric epipedon is 50 to 82 centimeters thick.
Soil reaction: very strongly acid to moderately acid throughout the soil profile.
Base saturation (by ammonium acetate) is less than 60 percent between 25 and 75 centimeters.
Surface Fragments: 0 to 5 percent gravel
Particle Size Control Section (weighted average):
Clay: 10 to 18 percent.
Rock fragments: ranges from 35 to 55 percent, mostly gravel and channers.
O horizon
Hue: 10YR.
Value: 2 through 6 dry and moist.
Chroma: 1 through 4 dry and moist.
Texture: slightly decomposed organic material.
Wood fragments: 0 to 35 percent.
Reaction: moderately to slightly acid.
A Horizon
Hue: 10YR or 2.5Y
Value: 4 or 5 dry, 2 through 4 moist.
Chroma: 2 through 6 dry, 2 or 3 moist.
Texture of fine earth fraction: sandy loam or loam
Clay content: 10 to 18 percent
Rock fragments: 0 to 25 percent gravel
Bw Horizons
Hue: 10YR or 2.5Y
Value: 3 through 5 dry, 3 or 4 moist.
Chroma: 3 through 6, dry or moist.
Texture of fine earth fraction: sandy loam or loam
Clay content: 10 to 18 percent
Rock fragments: 10 to 35 percent gravel and 5 to 30 percent cobble
2C Horizon
In lieu of texture: channers
Rock fragments: 90 to 100 channers, 0 to 5 percent gravel
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: These soils occur on mountain summits and upper mountain slopes with slopes of 9 to 50 percent. They are on convex slope positions at elevations of 992 to 1626 meters (3255 to 5335 feet). These soils formed in residuum and colluvium derived from schist. The climate is subhumid with warm dry summers and cold moist winters. The mean annual precipitation is 2032 to 2794 millimeters (80 to 110 inches). Mean January temperature is about 3 degrees C (37 degrees F); mean July temperature is about 15 degrees C (59 degrees F); and the mean annual temperature is 5 to 8 degrees C (41 to 47 degrees F). The frost free period is about 75 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the
Madbuttes series. The Madbuttes soil is on concave slope positions and is very deep with an argillic horizon.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well-drained; high runoff; moderately high saturated hydraulic conductivity.
USE AND VEGETATION: Used for timber production, wildlife habitat and watershed. Native vegetation is white fir, grand fir, incense cedar and Douglas-fir with an understory of snowberry, whitethorn ceanothus and bracken fern.
DISTRIBUTION AND EXTENT: Siskiyou-Trinity Area, MLRA 5. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Humboldt County, California, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Umbric epipedon - the zone from 2 to 82 centimeters (A1, A2, AB, and Bw horizons)
2. Depth to abrupt textual change is 82 centimeters.
3. Particle-size control section - the zone from 25 to 100 centimeters, (AB, Bw, and 2C) averages 16 percent clay, by weight, and 37 percent rock fragments, by volume, from 25 to 82 centimeters, and 1 percent clay, by weight, and 95 percent gravel, by volume, from 82 to 200 centimeters.
Additional Data:
NASIS User Pedon ID: 04CA023605064
Soil classified using the 12th Edition of the Keys to Soil Taxonomy. These soils were previously classified as Loamy-skeletal over fragmental, mixed, superactive, frigid Humic Dystroxerepts.
National Cooperative Soil Survey
U.S.A.