LOCATION CHILMARK MAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Oxyaquic Hapludults
TYPICAL PEDON: Chilmark sandy loam - idle grassland. (Colors are for moist soil.)
Ap--0 to 10 inches; very dark grayish brown (10YR 3/2) sandy loam, light brownish gray (10YR 6/2) dry; weak medium granular and weak medium subangular blocky structure; friable; many fine roots; moderately acid; abrupt wavy boundary. (8 to 11 inches thick)
Bw1--10 to 16 inches; dark yellowish brown (10YR 4/4) sandy loam; weak medium subangular blocky structure; friable; many fine roots; moderately acid; clear smooth boundary. (4 to 8 inches thick)
Bw2--16 to 27 inches; light olive brown (2.5Y 5/6) sandy loam; weak medium subangular blocky structure; friable; common fine roots; common faint clay films on sand grains and some clay bridges between sand grains; moderately acid; clear smooth boundary. (6 to 12 inches thick)
Bt1--27 to 31 inches; yellowish brown (10YR 5/4) sandy loam; weak medium angular blocky structure; friable; slightly sticky, nonplastic; few fine roots; common thin clay films on sand grains and clay bridges between most sand grains; moderately acid; abrupt smooth boundary. (3 to 6 inches thick)
2Bt2--31 to 36 inches; reddish brown (5YR 4/4), yellowish red (5YR 5/6 and 5/8), olive gray (5Y 5/2), olive (5Y 5/3 and 5/4), and light olive gray (5Y 6/2) poorly mixed or folded thin strata of sandy clay loam, silty clay loam, silty clay, and clay; weak coarse prismatic structure parting to moderate coarse angular blocky; extremely firm, very sticky, very plastic; moderate clay films on most faces of peds and in some pores; 5 percent gravel; moderately acid; clear smooth boundary. (4 to 7 inches thick)
2C--36 to 65 inches; reddish brown (5YR 4/4), yellowish red (5YR 5/6 and 5/8), olive gray (5Y 5/2), olive (5Y 5/3 and 5/4), and light olive gray (5Y 6/2) poorly mixed or folded thin strata of sandy clay loam, silty clay loam, silty clay, and clay; massive; extremely firm, very sticky, very plastic; 5 percent gravel; moderately acid.
TYPE LOCATION: Nantucket County, Massachusetts; Town of Nantucket, 0.8 mile southwest of the intersection of Milestone Road and Nobadeer Road. USGS Siasconset quadrangle; 41 degrees 15 minutes 41 seconds N., and 70 degrees 4 minutes 15 seconds W., NAD 27.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 25 to 44 inches. Rock fragment content is usually less than 5 percent, but ranges from 0 to 10 percent. The soil ranges from very strongly acid through moderately acid throughout.
The A or Ap horizon has hue of 5YR through 10YR, value of 3, and chroma of 2 or 3. Texture ranges from fine sandy loam to loamy sand. Structure is weak granular or subangular blocky, and consistence is friable or very friable.
The Bw horizon has hue of 7.5YR through 2.5Y, value of 4 or 5, and chroma of 4 through 6. Texture is sandy loam or loamy sand. It is massive or has subangular or angular blocky structure and is friable or very friable. The Bt horizon has hue of 10YR, value of 5, and chroma of 4 through 6. It is sandy loam.
The 2Bt horizon has hue of 2.5YR through 5Y, value of 4 through 7, and chroma of 1 through 8. It commonly is silty clay loam and averages less than 35 percent clay, but in undisturbed pedons consists of poorly mixed or folded thin strata (1/4 inch to 6 inches thick) of sandy clay loam, silty clay loam, silty clay, and clay. The 2Bt horizon is massive or it has weak prismatic structure that parts to weak blocky structure. Consistence varying within strata is firm to extremely firm, sticky to very sticky, and plastic to very plastic.
The 2C horizon has the same colors, textures and consistence as the 2Bt horizon.
COMPETING SERIES: Soils in the same family include the Hassler and Roselle series. Hassler soils (tentative) are deep to granite bedrock and formed in colluvium and residuum on mountain ridges in the Ozark Highland area (MLRA 116A). Roselle soils (tentative) formed in colluvium and residuum from granite on terraces and footslopes in mountain basins in the Ozark Highland area (MLRA 116A).
Birdsboro and Brumbaugh soils are in a closely related family. Birdsboro soils do not have sandy loam subhorizons in the B horizon. Brumbaugh soils (tentative) formed in colluvium and rock fragment content ranges from 5 to 50 percent in individual horizons.
GEOGRAPHIC SETTING: Chilmark soils are gently sloping to moderately steep soils on landscapes that are very close to the bases of terminal moraines and on gently sloping or undulating lower parts of the moraines. Slope ranges from 3 to 25 percent. The soils formed in a loamy or sandy aeolian mantle and the underlying ice-thrusted fine or moderately fine coastal plain sediments dominated by poorly mixed tertiary clays. Mean annual precipitation ranges from 40 to 50 inches. The frost-free season ranges from 180 to more than 200 days. Mean annual air temperature ranges from 48 to 52 degrees F..
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Eastchop, Evesboro, Nantucket, Plymouth, and Riverhead soils. All of these soils lack argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium. Permeability is moderately rapid in the upper part of the solum, and slow in the lower part of the solum and in the substratum.
USE AND VEGETATION: Most of these soils are in idle grassland or scrubby brushland. Vegetation consists of poverty grass, bluestem, bayberry, poison ivy, pasture rose, white and red oak, and pitch pine. These soils are generally not used for farming.
DISTRIBUTION AND EXTENT: MLRA 149B on the islands of Nantucket and Martha's Vineyard in Massachusetts and possibly Long Island, New York. The soils are not extensive. There are 2,328 acres in Massachusetts.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Amherst, Massachusetts
SERIES ESTABLISHED: Dukes and Nantucket Counties, Massachusetts, 1925.
REMARKS: Cation-exchange activity class is presumed from a review of data for similar soils. Changes in competing series may result from updates in classification.
Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon - the zone from 0 to 10 inches (Ap horizon).
2. Cambic horizon - the zone from 10 to 27 inches (Bw1 and Bw2 horizons).
3. Argillic horizon - the zone from 27 to 36 inches (Bt and 2Bt horizons).
4. Fine-loamy feature - the zone from 27 to 36 inches has more than 15 percent sand that is coarser than very fine sand, including gravel, and clay content averages about 22 percent (Bt and 2Bt horizons).
5. Oxyaquic feature - presence of a saturated layer at 31 inches (2Bt horizon) for more than 1 month most years.