LOCATION PLATEA OH+PA
Established Series
Rev. JRS-STP-AWD
03/2016
PLATEA SERIES
The Platea series consists of very deep, somewhat poorly drained soils formed in Wisconsinan age till on till plains and moraines. It is shallow or moderately deep to a fragipan. Saturated hydraulic conductivity is moderately high above the fragipan and low to moderately low in the fragipan and the substratum. Slope ranges from 0 to 15 percent. Mean annual precipitation is about 1065 mm (42 in), and mean annual temperature is about 9 degrees C (48 degrees F).
TAXONOMIC CLASS: Fine-silty, mixed, active, mesic Aeric Fragiaqualfs
TYPICAL PEDON: Platea silt loam, on a convex, 3 percent slope in mixed hardwoods at an elevation of about 265 m (870 ft) above msl. (Colors are for moist soil unless otherwise stated.)
A--0 to 10 cm (0 to 4 in); very dark grayish brown (10YR 3/2) silt loam, light brownish gray (10YR 6/2) dry; moderate medium and coarse granular structure; friable; common medium and coarse and many very fine and fine roots; about 1 percent rock fragments; very strongly acid; clear smooth boundary. (5 to 13 cm [2 to 5 in] thick)
E--10 to 23 cm (4 to 9 in); pale brown (10YR 6/3) silt loam; weak fine and medium subangular blocky structure; friable; common very fine to coarse roots; many distinct very dark grayish brown (10YR 3/2) organic coats in root channels; common fine and medium faint light brownish gray (10YR 6/2) iron depletions in the matrix; few (less than 15 percent by volume) fine faint light brownish gray (10YR 6/2) clay depletions on faces of peds; common fine and medium prominent strong brown (7.5YR 5/6) masses of iron accumulation in the matrix; about 2 percent rock fragments; very strongly acid; clear wavy boundary. (0 to 28 cm [0 to 11 in] thick)
Bt--23 to 41 cm (9 to 16 in); dark yellowish brown (10YR 4/4) silty clay loam; moderate medium and coarse subangular blocky structure; friable; few very fine to medium roots; few faint brown (7.5YR 4/4) clay films lining tubular pores; common distinct light brownish gray (2.5Y 6/2) coats on vertical and horizontal faces of peds; common fine and medium distinct light brownish gray (10YR 6/2) iron depletions in the matrix; many coarse and very coarse prominent gray (5Y 5/1) clay depletions on faces of peds; yellowish red (5YR 5/6) masses of iron accumulation in the matrix; about 3 percent rock fragments; very strongly acid; clear irregular boundary. (15 to 41 cm [6 to 16 in] thick)
Btx1--41 to 74 cm (16 to 29 in); brown (10YR 4/3) silt loam; strong very coarse prismatic structure parting to weak thick platy; very firm and brittle; few fine and medium roots between peds; many prominent gray (N 6/0) iron-depleted clay films on vertical faces of peds; common fine and medium distinct light brownish gray (2.5Y 6/2) clay depletions on vertical faces of peds; rind inside coats is strong brown (7.5YR 5/6); common medium and coarse prominent strong brown (7.5YR 5/6) masses of iron accumulation in the matrix; common fine black (10YR 2/1) slightly hard manganese oxide concretions throughout; about 3 percent rock fragments; strongly acid grading to slightly acid; gradual wavy boundary.
Btx2--74 to 114 cm (29 to 45 in); brown (10YR 4/3) silt loam; strong very coarse prismatic structure parting to moderate medium platy; very firm and brittle; few very fine and fine roots between peds; many prominent gray (N 6/0) iron-depleted clay films on vertical faces of peds; common fine and medium distinct light brownish gray (2.5Y 6/2) clay depletions on vertical faces of peds; rind inside coats is brown (7.5YR 4/4); few fine black (10YR 2/1) slightly hard manganese oxide concretions throughout; about 10 percent rock fragments; neutral; clear wavy boundary. (Combined thickness of the Btx horizons is 25 to 102 cm [10 to 40 in].)
BC--114 to 157 cm (45 to 62 in); yellowish brown (10YR 5/4) silt loam; weak medium subangular blocky structure; firm; common prominent gray (N 6/0) iron-depleted on vertical faces of peds; few medium distinct yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common fine very pale brown (10YR 8/2) soft calcium carbonate concretions throughout; about 5 percent rock fragments; slightly effervescent; moderately alkaline; clear wavy boundary. (0 to 51 cm [0 to 20 inches] thick)
C--157 to 203 cm (62 to 80 in); yellowish brown (10YR 5/4) silt loam; massive; firm; few medium distinct gray (10YR 6/1) areas of iron depletion and yellowish brown (10YR 5/6) masses of iron accumulation in the matrix; common fine very pale brown (10YR 8/2) slightly hard calcium carbonate concretions throughout; about 8 percent rock fragments; strongly effervescent; moderately alkaline.
TYPE LOCATION: Ashtabula County, Ohio; about 3.0 miles north of Jefferson, in Jefferson Township, 5,500 feet west of the intersection of Clay Street (County Road 16) and State Route 46 along Clay Street, then 100 feet south, T. 11 N., R. 3 W.; USGS Ashtabula South, Ohio topographic quadrangle; Latitude 41 degrees, 46 minutes, 53 seconds N. and Longitude 80 degrees, 47 minutes, 3 seconds W., NAD 1983.
RANGE IN CHARACTERISTICS: Thickness of the solum ranges from 86 to 165 cm (34 to 65 in). Depth to the top of the fragipan ranges from 36 to 66 cm (14 to 26 in). The particle-size control section averages 22 to 34 percent clay. Depth to carbonates ranges from 76 cm to greater than 203 cm (30 to greater than 80 in).
The A horizon has hue of 10YR, value of 2 or 3 (4 to 6 dry), and chroma of 1 or 2. Pedons that have an Ap horizon have hue of 10YR, value of 3 or 4 (6 or more dry), and chroma of 2 or 3. Texture is silt loam. Structure is weak or moderate, fine to coarse, granular. Rock fragments range from 0 to 5 percent. Reaction is extremely acid to moderately acid.
The E horizon has hue of 10YR or 2.5Y, value of 5 or 6 (6 or more dry), and chroma of 2 to 4. Texture is silt loam. Structure is weak or moderate, fine or medium, subangular blocky. Rock fragments range from 0 to 5 percent. Reaction is extremely acid to moderately acid.
The Bt horizon has hue of 7.5YR, 10YR or 2.5Y, value of 4 to 6, and chroma of 2 to 8. Texture is silty clay loam or silt loam. Some pedons have thin strata of clay loam or loam. Structure is weak or moderate, fine to coarse, subangular blocky. Rock fragments range from 0 to 5 percent. Reaction is extremely acid to moderately acid.
The Btx horizon has hue of 7.5YR, 10YR or 2.5Y, value of 4 or 5, and chroma of 3 to 6. Texture is silt loam, silty clay loam, loam, clay loam or their gravelly or channery analogues. Structure is moderate or strong, coarse or very coarse prismatic, parting to subangular blocky or platy in some pedons. Rock fragments range from 1 to 20 percent. Reaction is very strongly acid to neutral.
The BC horizon has hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 1 to 6. Texture is silt loam, silty clay loam, loam, clay loam or their gravelly or channery analogues. Structure is weak or moderate, coarse or very coarse, prismatic sometimes parting to subangular blocky or platy; weak or moderate, medium to coarse, subangular blocky; weak, thin to thick, platy. Rock fragments range from 5 to 35 percent. Reaction is moderately acid to moderately alkaline.
The C horizon has hue of 10YR or 2.5Y, value of 4 or 5, and chroma of 1 to 6. Texture is silt loam, silty clay loam, loam, clay loam or their gravelly or channery analogues. Rock fragments range from 5 to 35 percent. Reaction is neutral to moderately alkaline.
COMPETING SERIES: These are the
Bartle,
Doles,
Dubois,
Patricksburg,
Schaffer,
Wadsworth, and
Weinbach series. Bartle and Doles soils have no rock fragments in or below the fragipan. Dubois and Schaffer soils have thicker sola. The depth to the top of the fragipan in Patricksburg soils is 76 to 102 cm (30 to 40 in) and to a paralithic contact is 152 to 203 cm (60 to 80 in). Wadsworth soils formed in older age till and in slightly different climate characterized by less snow and slightly lower precipitation. Weinbach soils lack an argillic horizon above the fragipan and have mica flakes throughout the solum.
GEOGRAPHIC SETTING: Platea soils formed in low-lime Wisconsinan age till strongly influenced by clayey shale and siltstone and are on summits, shoulders and backslopes on till plains and moraines. Slope ranges from 0 to 15 percent. Mean annual precipitation ranges from 830 to 1320 mm (33 to 52 in) and mean annual temperature ranges from 6 to 11 degrees C. (42 to 50 degrees F.).
GEOGRAPHICALLY ASSOCIATED SOILS: These are the
Blakeslee,
Darien,
Fitchville,
Glenford,
Mill,
Pierpont,
Red Hook and
Sebring series. The moderately well drained Pierpont and poorly drained Mill soils are in a drainage sequence with Platea soils. The moderately well drained Blakeslee and somewhat poorly drained Red Hook soils do not have a fragipan and are on nearby outwash plains and terraces. The somewhat poorly drained Darien soils do not have a fragipan and are on similar landscape positions. The somewhat poorly drained Fitchville, moderately well drained Glenford and poorly drained Sebring soils do not have a fragipan and are on nearby lake plains and terraces.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Somewhat poorly drained. Saturated hydraulic conductivity is moderately high above the fragipan and low or to moderately low in the fragipan and the substratum. Depth to the top of an intermittent perched seasonal high water table is from 15 to 30 cm (0.5 to 1.0 ft) from October to June in most years.
USE AND VEGETATION: Dominant uses are cropland, pasture and hayland, woodland, and abandoned cropland. Crops include wheat, oats, timothy, clover, corn, buckwheat, birdsfoot trefoil, and soybeans. Native vegetation is hardwood forest, chiefly beech, sugar maple, ironwood, wildcherry, basswood, elm, ash, red maple, and red oak.
DISTRIBUTION AND EXTENT: In northeastern Ohio and northwestern Pennsylvania. MLRA 139. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Amherst, Massachusetts.
SERIES ESTABLISHED: Erie County, Pennsylvania, 1958.
REMARKS: Diagnostic horizons and features recognized in this pedon include:
1. Ochric epipedon - from a depth of 0 to 23 cm (0 to 9 in) (A and E horizons).
2. Aquic conditions beginning at a depth of 10 cm (4 in).
3. Argillic horizon and fragipan feature - from a depth of 41 to 114 cm (16 to 45 in) (Btx1 and Btx2 horizons).
During the modernization of the Ashtabula County Soil Survey, a pedon located as near as possible to the original typifying pedon was described to 203 cm (80 in) and reviewed at the October, 1993 progress field review. That pedon has been installed as the new series typifying pedon. Reviewers a t the time noted some evidence of translocated clay above the fragipan, after much debate this was deemed to be an argillic horizon. Further review of past documentation and correlation of the Wadsworth series has been recommended to determine whether sufficient differentia exists between the Platea and Wadsworth series.
ADDITIONAL DATA: Characterization data for the Platea series can be found at the NCSS Soil Characterization Database.
National Cooperative Soil Survey
U.S.A.