Soil Survey of McHenry County, Illinois Part I - Soil Data Mart

126 Soil Survey of
Similar soils:
• soils that are moderately eroded
• soils that have a darker subsurface layer
• soils that contain carbonates at a depth of less than
20 inches or more than 40 inches
• soils that have slopes of less than 20 percent or
more than 30 percent
Dissimilar soils:
• the poorly drained Pella soils in drainageways
• Fox soils, which contain sandy and gravelly
deposits at a depth of less than 40 inches; in the lower
positions on the landform
Management
For general and detailed information about
managing this map unit, see the following sections in
Part II of this publication:
• “Forestland” section
• “Wildlife Habitat” section
• “Engineering” section
• “Soil Properties” section
Thorp Series
Drainage class: Poorly drained
Permeability: Slow
Landform: Outwash plains, stream terraces, and till
plains
Parent material: Silty material and the underlying
loamy outwash
Slope range: 0 to 2 percent
Taxonomic classification: Fine-silty, mixed, mesic
Argiaquic Argialbolls
Typical Pedon for MLRA 95B
Typical pedon of Thorp silt loam, 0 to 2 percent
slopes, 2,500 feet south and 200 feet west of the
northeast corner of sec. 18, T. 45 N., R. 5 E.
Ap—0 to 11 inches; 95 percent very dark grayish
brown (10YR 3/2) and 5 percent grayish brown
(10YR 5/2) silt loam, grayish brown (10YR 5/2)
dry; weak medium subangular blocky structure
parting to weak medium granular; friable; common
very fine roots; common fine and medium black (N
2.5/0) very weakly cemented iron and manganese
oxide concretions throughout; neutral; abrupt
smooth boundary.
Eg—11 to 18 inches; grayish brown (10YR 5/2) silt
loam, very pale brown (10YR 7/3) dry; weak fine
and medium subangular blocky structure; friable;
common very fine roots; very few distinct very
dark grayish brown (10YR 3/2) organic coatings in
root channels and in pores; few fine and medium
black (N 2.5/0) iron and manganese oxide
concretions throughout; common fine and medium
prominent yellowish brown (10YR 5/6) and
common medium faint pale brown (10YR 6/3)
masses of iron accumulation in the matrix;
moderately acid; clear smooth boundary.
BEg—18 to 22 inches; grayish brown (2.5Y 5/2) silt
loam; weak fine subangular blocky structure;
friable; common very fine roots; very few distinct
dark grayish brown (2.5Y 4/2) coatings on faces of
peds; few fine and medium black (N 2.5/0) very
weakly cemented iron and manganese oxide
concretions throughout; common fine and medium
prominent yellowish brown (10YR 5/6) and
common fine prominent strong brown (7.5YR 5/6)
masses of iron accumulation in the matrix; many
medium and coarse faint light brownish gray (2.5Y
6/2) iron depletions in the matrix; moderately acid;
gradual smooth boundary.
Btg1—22 to 30 inches; light brownish gray (2.5Y 6/2)
silty clay loam; moderate fine and medium
subangular blocky structure; firm; common very
fine roots; few distinct grayish brown (2.5Y 5/2)
clay films on faces of peds; very few distinct very
dark grayish brown (10YR 3/2) organic coatings
on faces of peds; common fine and medium black
(N 2.5/0) very weakly cemented iron and
manganese oxide concretions throughout;
common fine and medium prominent strong brown
(7.5YR 5/6) masses of iron accumulation in the
matrix; slightly acid; clear smooth boundary.
Btg2—30 to 38 inches; gray (5Y 6/1) silty clay loam;
moderate medium prismatic structure parting to
moderate medium subangular blocky; firm;
common very fine roots; few distinct gray (5Y 5/1)
clay films on faces of peds; few fine and medium
black (N 2.5/0) very weakly cemented iron and
manganese oxide concretions throughout;
common medium prominent yellowish brown
(10YR 5/6) and dark yellowish brown (10YR 4/6)
masses of iron accumulation in the matrix;
moderately acid; clear smooth boundary.
2Btg3—38 to 49 inches; gray (5Y 6/1) clay loam; weak
medium prismatic structure parting to moderate
medium subangular blocky; friable; common very
fine roots; very few distinct gray (5Y 5/1) clay films
on faces of peds; common fine and medium black
(N 2.5/0) very weakly cemented iron and
manganese oxide concretions throughout;
common medium prominent yellowish brown
(10YR 5/6) and dark yellowish brown (10YR 4/6)