LOCATION SOUTHPOINT MDTentative Series
TAXONOMIC CLASS: Fine-silty, mixed, subactive, nonacid, mesic Thapto-histic Sulfaquents
TYPICAL PEDON: Southpoint sand on a smooth 0.5 percent slope in a deep mainland cove under 4.2 feet of permanent estuarine water. (Colors are for moist soil.)
Ag--0 to 2 inches; black (N 2.5/0) sand; single grain; loose; 5 percent, by volume black (10YR 2/1) organic fragments; moderately alkaline; strongly saline; abrupt smooth boundary. (1 to 5 inches thick)
Cg1--2 to 4 inches; very dark gray (5Y 3/1) loam; single grain; loose; moderately alkaline; strongly saline; abrupt smooth boundary. (0 to 9 inches thick)
2Cg2--4 to 9 inches; dark olive gray (5Y 3/2) silty clay; massive; firm; n-value 1.0, material flows easily between fingers when squeezed; slightly alkaline; strongly saline; clear smooth boundary.
2Cg3--9 to 22 inches; dark bluish gray (10B 4/1) silty clay loam; massive; firm; n-value 1.0, material flows easily between fingers when squeezed; slightly alkaline; strongly saline; clear smooth boundary.
2Cg4--22 to 36 inches; olive gray (5Y 4/2) silty clay; massive; firm; n-value 1.0, material flows easily between fingers when squeezed; slightly alkaline; strongly saline; clear smooth boundary. (24 to 38 inches thick)
Oeb--36 to 48 inches; dark brown (7.5YR 3/2) mucky peat; hemic soil material, 50 percent, by volume rubbed fiber; 20 percent, by volume light olive brown (2.5Y 5/4) organic fragments; slightly alkaline; strongly saline; gradual smooth boundary.
Oab--48 to 60 inches; black (N 2.5/0) muck; sapric soil material, 10 percent, by volume rubbed fiber; slightly alkaline; strongly saline. (Combined thickness of the O horizon is 8 or more inches thick.)
TYPE LOCATION: Worcester County, Maryland; approximately 1.2 miles north of South Point along the mainland, 100 feet east of the mainland, Sinepuxent Bay, in an unvegetated area; lat. 38 degrees, 13 minutes, 54.48 seconds N. and long. 75 degrees, 10 minutes, 51.96 seconds W.
RANGE IN CHARACTERISTICS:
Depth to Bedrock: Greater than 80 inches
Depth to Seasonal High Water Table: Permanently submersed
Depth to Lithologic Discontinuity: 1 to 10 inches
Shell Fragments: 0 to 5 percent, by volume
Soil Reaction: Slightly alkaline to moderately alkaline throughout the profile
Electrical Conductivity: Greater than 16 mmhos/cm throughout the profile
Salinity: Greater than 25 ppt throughout the profile
Other Features: Depth to the buried organic surface is 16 to 40 inches
RANGE OF INDIVIDUAL HORIZONS:
Ag horizon:
Color--hue of 10YR to 5Y, value of 3 to 5, and chroma of 1 or 2, or is neutral with value of 3 to 5
Texture--sand or loamy sand
Cg horizon:
Color--hue of 10YR to 10Y, value of 3 to 6, and chroma of 1 or 2, or is neutral with value of 3 to 6
Texture--sandy loam, loam or loamy sand
2Cg horizon:
Color--hue of 2.5Y to 10B, value of 3 to 6, and chroma of 1 or 2, or is neutral with value of 3 to 6
Texture--silty clay, silty clay loam or silt loam
Oib, Oeb or Oab horizon:
Color--hue of 7.5YR to 5Y, value of 2 to 4, and chroma of 1 or 2, or is neutral with value of 2 to 4
Texture--peat, mucky peat or muck
COMPETING SERIES: None
GEOGRAPHIC SETTING:
Landscape: Mid-Atlantic Coastal Plain Estuaries
Landform: Deep mainland coves and large basins
Parent Material: Silty terrestrial tidal marsh sediments overlying paleo-terrestrial organic deposits
Slope: 0 to 3 percent
Mean Annual Air Temperature: 50 to 57 degrees F.
Mean Annual Water Temperature: 52 to 58 degrees F.
Bathymetry: 1.5 to 9.5 feet below MSL
Water Regime: Tidal, 1.0 to 2.0 feet tidal range
GEOGRAPHICALLY ASSOCIATED SOILS:
Demas soils (tentative)--do not have a buried histic epipedon within 40 inches of the surface; at shallower water depths
Mispillion soils--are not permanently submerged; have surface organic layers 16 to 51 inches thick; on adjacent tidal marshes
Transquaking soils--are not permanently submerged, have organic surface layers more than 51 inches thick; on adjacent tidal marshes
DRAINAGE AND PERMEABILITY:
Agricultural Drainage Class: Very poorly drained (permanently submersed)
Index Surface Runoff: Negligible
Permeability: Moderately slow or slow
USE AND VEGETATION:
Major Uses: Most areas are unvegetated and function as estuarine benthic wildlife habitat is limited. Benthic fauna such as tubeworms, clams, juvenile blue crabs, scallops and juvenile finfish are rare.
Dominant Vegetation: Native vegetation includes rooted algae, eelgrass (Zostera marina) and widgeon grass (Ruppia maritima). Vegetative cover ranges from 0 to 5 percent.
DISTRIBUTION AND EXTENT: The Mid-Atlantic coastal estuaries of Maryland and Delaware and possibly Virginia. This series is of small extent.
MLRA OFFICE RESPONSIBLE: Morgantown, West Virginia
SERIES PROPOSED: Worcester County, Maryland, 1998.
REMARKS: Southpoint soils were formerly included with miscellaneous areas of water. They are distinguished by being permanently covered by estuarine waters that support limited submersed aquatic vegetation. These soils would classify in the proposed "Subaquic Thapto-histic subgroup. The original proposed series name was spelled "South Point." Refer to "Subaqueous Soil Survey of Sinepuxent Bay, Maryland;" G.P. Demas, J.H. Brown, and M.C. Rabenhorst; July 1998.
Diagnostic horizons and other diagnostic soil characteristics recognized in this pedon are:
Ochric epipedon (oxidized)--the zone from 0 to 2 inches (Ag horizon)
Peraquic feature--the zone from 0 to 60 inches is permanently saturated
Sulfidic feature--The zone from 4 to 36 inches contains sulfidic materials (verified by moist incubation)
Thapto-histic feature--the zone from 36 to 60 inches (Oeb and Oab horizons)
ADDITIONAL DATA:
This pedon was sampled as S97MD047-001. Radiocarbon analysis of a wood sample from the buried organic layer at a depth of 36 inches yielded a date of 1400 years B.P.
Data Map Unit ID: To be developed