LOCATION NOARK AR+MOEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, mixed, semiactive, mesic Typic Paleudults
TYPICAL PEDON: Noark very gravelly silt loam, forested. (Colors are for moist soil unless otherwise stated.)
A--0 to 3 inches; dark grayish brown (10YR 4/2) very gravelly silt loam; moderate medium granular structure; friable; many medium roots; about 40 percent by volume angular chert fragments less than 3 inches in diameter; very strongly acid; abrupt smooth boundary. (1 to 7 inches thick)
E--3 to 12 inches; brown (10YR 5/3) very gravelly silt loam; weak medium subangular blocky structure; friable; many fine roots; about 40 percent by volume angular chert fragments less than 3 inches in diameter; extremely acid; clear wavy boundary. (6 to 14 inches thick)
BE--12 to 19 inches; yellowish red (5YR 4/6) very gravelly silty clay loam; pockets and streaks of brown (10YR 5/3) silt loam; moderate medium subangular blocky structure; firm; many fine roots; about 40 percent by volume angular chert fragments less than 3 inches in diameter; very strongly acid; clear wavy boundary. (0 to 11 inches thick)
2Bt1--19 to 26 inches; red (2.5YR 4/6) very gravelly clay; strong medium blocky structure; very firm; common fine roots; common fine pores; many thin patchy clay films on ped faces and chert fragments; about 40 percent by volume angular chert fragments less than 3 inches in diameter; extremely acid; gradual wavy boundary.
2Bt2--26 to 37 inches; dark red (2.5YR 3/6) very gravelly clay; strong medium blocky structure; very firm; few fine roots; common fine pores; thick continuous clay films on ped faces and chert fragments; about 50 percent by volume chert fragments less than 3 inches in diameter; extremely acid; gradual wavy boundary.
2Bt3--37 to 80 inches; dark red (2.5YR 3/6) extremely gravelly clay; strong medium blocky structure; very firm; thick continuous clay films on ped faces and chert fragments; about 70 percent by volume angular chert fragments less than 3 inches in diameter; extremely acid. (Combined thickness of the 2Bt horizon ranges from 31 to 73 inches or more.)
TYPE LOCATION: Benton County, Arkansas; south of Highway 12, at road fork to War Eagle; 14 miles from Rogers; SE1/4SE1/4SW1/4 sec. 27, T. 19 N., R. 28 W.
RANGE IN CHARACTERISTICS:
Depth to Bedrock: greater than 80 inches
Note: Some pedons have clay depletions of 2 chroma or less at depths greater than 40 inches.
A or Ap horizon
Hue: 10YR
Value: 3 to 5
Chroma: 2 to 4
Fine earth: silt loam
Total rock fragments: 15 to 60 percent; 15 to 60 percent gravel and 0 to 15 percent cobbles
Reaction: very strongly acid to slightly acid
Note: Where the color value is 3 or less, the thickness is less than 6 inches
E horizon
Hue: 10YR
Value: 5 or 6
Chroma: 3 or 4
Fine earth: silt loam
Total rock fragments: 15 to 60 percent; 15 to 60 percent gravel and 0 to 10 percent cobbles
Reaction: very strongly acid to slightly acid
BE or Bt horizon
Hue: 5YR to 10YR
Value: 4 or 5
Chroma: 4 or 6
Fine-earth: silt loam or silty clay loam
Total rock fragments: 35 to 65 percent; 20 to 65 percent gravel and 0 to 20 percent cobbles
Reaction: extremely acid to medium acid
2Bt horizon
Hue: 10R to 7.5YR
Value: 3 to 5
Chroma: 4 to 8
Fine-earth: silty clay or clay
Total rock fragments: 25 to 80 percent, 15 to 80 percent gravel and 0 to 50 percent cobbles
Reaction: extremely acid to strongly acid
COMPETING SERIES: There no other series in this family.
GEOGRAPHIC SETTING: Noark soils are on nearly level to very steep uplands of the Ozark Highlands. These soils formed in colluvium and clayey residuum weathered from cherty limestone. Slopes range from 1 to 45 percent. Near the type location, the average annual temperature is about 56 degrees F., and the average annual precipitation is about 45 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arkana, Clarksville, Captina, Moko, Nixa and Tonti series. Arkana soils are near limestone outcrops, have a very-fine control section, a 20 to 40 inch solum, and higher base saturation. Clarksville soils occur on similar sideslope positions as Noark soils and have a loamy-skeletal control section. Captina soils occur on broad flats, have a fine-silty control section, and a fragipan. Moko soils are near limestone outcrops, have a loamy-skeletal control section, a 10 to 20 inch sola and higher base saturation. Nixa soils are on narrow ridgetops, have a loamy-skeletal control section, and a fragipan. Tonti soils are on broad flats, have a fine-loamy control section and a fragipan.
DRAINAGE AND PERMEABILITY: Well drained; medium to very high runoff; moderate permeability.
USE AND VEGETATION: Most areas are in mixed hardwood forest of red, white, post and blackjack oaks, hickory, with some black walnut and shortleaf pine. Cleared areas are used mainly for pasture.
DISTRIBUTION AND EXTENT: The Ozarks region (MLRA's 116A and 116B) of northwestern Arkansas, southwestern Missouri and northeastern Oklahoma. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Morgantown, West Virginia
SERIES ESTABLISHED: Benton County, Arkansas; 1973.
REMARKS: Diagnostic horizons recognized in this pedon are:
Ochric epipedon- the zone from the surface to a depth of 19 inches (A, E, and BE horizons).
Argillic horizon- the zone from 19 to 80 inches (Bt horizons).
The Noark series was formerly included in the Baxter and Clarksville series.
In Arkansas, these soils are mapped primarily in the Boone limestone geologic formation. In Missouri they are mapped mainly in the Mississippian age Burlington and Kinderhook limestone formations.