LOCATION EASTHAM TXEstablished Series
TAXONOMIC CLASS: Fine, smectitic, thermic Typic Hapluderts
TYPICAL PEDON: Eastham clay--pasture (Colors are for moist soil unless otherwise stated)
A1--0 to 4 inches; very dark gray (10YR 3/1) clay; moderate fine and medium angular blocky structure; very hard, very firm; many fine and medium roots; few fine vesicular and tubular pores; few siliceous pebbles; neutral; clear wavy boundary.
A2--4 to 17 inches; very dark gray (10YR 3/1) clay; moderate medium angular blocky structure; very hard, very firm; many fine and medium roots; few fine vesicular and tubular pores; few prominent dark yellowish brown stains of iron-manganese; few pressure faces; few siliceous pebbles; few medium faint grayish brown (10YR 5/2) redox concentrations; slightly acid; gradual wavy boundary. (combined thickness of A horizons 12 to 22 inches)
Bss1--17 to 27 inches; black (5Y 2.5/1) clay; moderate medium and coarse angular blocky structure; very hard, very firm; common fine roots; few fine vesicular and tubular pores; few prominent brown and dark brown stains of iron-manganese; many slickensides; few siliceous pebbles; few medium distinct brown (10YR 5/3) relic redox concentrations or masses with sharp boundaries; slightly acid; gradual wavy boundary.
Bss2--27 to 40 inches; black (5Y 2.5/1) clay; moderate medium angular blocky structure; very hard, very firm; common fine roots; few fine vesicular and tubular pores; many slickensides that are tilted 45 to 50 degrees from horizontal; few siliceous pebbles; neutral; clear wavy boundary.(combined thickness of Bss horizons 18 to 40 inches)
Bkss1--40 to 46 inches; dark gray (10YR 4/1) clay; moderate medium angular blocky structure; very hard, very firm; common fine roots; few fine vesicular and tubular pores; many slickensides; common fine masses and threads of calcium carbonate; many medium distinct light olive brown (2.5Y 5/4) relic redox concentrations or masses with sharp boundaries; weakly effervescent; moderately alkaline; clear wavy boundary.
Bkss2--46 to 57 inches; dark grayish brown (2.5Y 4/2) clay; moderate coarse angular blocky structure; very hard, very firm; few fine roots; few fine vesicular and tubular pores; common slickensides; common fine concretions and masses and few fine threads of calcium carbonate; common fine and medium faint grayish brown (2.5Y 5/2) and common fine distinct olive yellow (2.5Y 6/6) redox concentrations; weakly effervescent; moderately alkaline; gradual wavy boundary.(combined thickness of Bkss horizons 10 to 26 inches)
BCkss--57 to 70 inches; gray (10YR 6/1) clay; moderate medium angular blocky structure; very hard, very firm; few fine roots; few fine vesicular and tubular pores; many slickensides; common fine masses, concretions, and threads of calcium carbonate; many medium prominent yellowish brown (10YR 5/6) and dark yellowish brown (10YR 4/6) relic redox concentrations or masses with sharp boundaries; strongly effervescent; moderately alkaline; gradual wavy boundary. (10 to 30 inches thick)
BCss--70 to 88 inches; light brownish gray (10YR 6/2) clay; weak medium angular blocky structure; very hard, firm; few fine roots; few fine vesicular and tubular pores; many slickensides; few fine concretions and masses of calcium carbonate; few pitted nodules of calcium carbonate; many medium prominent brownish yellow (10YR 6/8), and few fine distinct dark yellowish brown (10YR 4/6) relic redox concentrations or masses with sharp boundaries; slightly alkaline
TYPE LOCATION: Houston County, Texas; from intersection of Loop 304 and Texas Highway 21 on the west side of Crockett; about 18 miles southwest on Texas Highway 21 to intersection of Farm Road 2498; .35 of a mile east on private road; .15 of a mile north in pasture to site. (Longitude: 95 degrees, 40 minutes, 24 seconds west; Latitude: 31 degrees, 7 minutes, 04 seconds north)
RANGE IN CHARACTERISTICS: The solum is more than 80 inches thick. The control section has an average clay content of 45 to 60 percent. Unless cultivated there is gilgai microrelief with microknolls about 6 to 10 inches higher than microdepressions. When dry, cracks 1 to 3 inches wide extend from the surface to a depth of more than 40 inches. The cracks are open for 60 to 90 cumulative days during normal years. Slickensides begin at a depth of 12 to 22 inches. The amplitude of waviness of mollic to nonmollic colors ranges from 20 inches thick on the microknolls to about 50 inches in the microdepression. Some microknolls have chimneys that do not have mollic colors. However, these make up less than 5 percent of most soil areas. Redox features or masses are considered to be relic.
The A horizon has hue of 10YR or 5Y, values of 2 or 3, and chroma of 1 or less. Thickness of the A horizon is variable due to microrelief, ranging from 6 inches on the microknolls to 22 inches in the microdepressions. It averages more than 12 inches thick in over half the pedon. Reaction ranges from moderately acid to slightly alkaline.
The Bss and Bkss horizons have hue of 10YR, 2.5Y or 5Y, value of 3 to 6, and chroma of 2 or less. Redox concentrations in shades of brown, yellow, or olive range from none to common. Redox concentrations are mainly in the Bkss horizons. Concretions, masses, and threads of calcium carbonate range from none to common. Reaction ranges from moderately acid to moderately alkaline in the Bss horizon, and from neutral to moderately alkaline in the Bkss horizon.
The BCss or BCkss horizon has hue of 10YR, 2.5Y, or 5Y, value of 4 to 6, and chroma of 1 to 6. Redox concentrations in shades of brown, yellow and olive range from few to many. In some pedons the horizon is variegated in these colors. Concretions, masses and threads of calcium carbonate range from few to common. Gypsum crystals range from none to few. Reaction ranges from neutral to moderately alkaline.
COMPETING SERIES: These are the Hallsbluff and Tinn series in the same family, and the Burleson, Lake Charles, and Laewest soils in closely related families. Hallsbluff soils have dominent chroma of 2 within the upper 12 inches. Tinn soils are on lower flood plain positions and are calcareous throughout. Burleson soils have an Ustic soil moisture regime. Lake Charles soils are on alluvial plains and delta plains on the coast prairie and have less amplitude of waviness in the mollic epipedon. Tinn soils are on flood plains of streams that drain the Blackland Prairie and have less amplitude of waviness in the mollic epipedon. Laewest soils are in the hyperthermic temperature regime.
GEOGRAPHIC SETTING: Eastham soils are mainly on first and second level terraces of the Trinity River. Slope gradients are mainly less than 2 percent, but range from 0 to 5 percent. The soil formed in alkaline clayey alluvial sediments. The average annual temperature ranges from 65 to 68 degrees F. The average annual rainfall ranges from 40 to 46 inches and the Thornwaite P-E index ranges from 66 to 70. The elevation ranges from 115 to 225 feet above sea level; frost free days range from 230 to 240.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Garner, Kaufman, Kosse, and Texark soils. Garner soils are on similar or slightly lower positions. Kaufman, Kossee, and Texark soils are on lower flood plain positions. Garner soils have dominant color value of 4 or more within 12 inches of the soil surface. Kosse soils have a fine-loamy control section. Kaufman and Texark soils have a very-fine control section.
DRAINAGE AND PERMEABILITY: Moderately well drained; water enters the soil rapidly when it is dry and cracked, but very slowly when wet; very slow permeability. Runoff is high on slopes up to 1 percent, and very high on slopes more than 1 percent.
USE AND VEGETATION: This soil is mainly used for cropland or improved pasture. Crops include cotton, corn, small grain and milo. Improved bermudagrass is the most common pasture grass.
DISTRIBUTION AND EXTENT: Western Coastal Plain (MLRA 133B) in eastern Texas. The Eastham series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Houston County, Texas; 1991.
REMARKS: Eastham soils were formerly included in the Burleson series. The name is from the nearby Eastham Prison Unit.
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon ----- 0 to 40 inches (A1, A2, and Bss horizons).
Cambic horizon ------ 40 to 88 inches(Bkss, BCkss, and BCss horizons).
Slickensides -------- 17 to 88 inches(Bss, Bkss, BCkss, and BCss horizons).
Secondary corbonates- 40 to 70 inches (Bkss and BCkss horizons).
ADDITIONAL DATA: Chemical and physical analyses were run by Texas A&M University on the type location pedon (S90TX-225-001)