LOCATION COINJOCK                NC+VA

Tentative Series
JDK-RBT
09/2026

COINJOCK SERIES

MLRA(s)--153B
Depth class--Very deep
Drainage class--Very poorly drained
Parent material--Herbaceous organic material over loamy estuarine deposits
Geomorphic location--Estuarine tidal marshes
Slope range--0 to 1 percent
Mean annual air temperature--17 degrees C (63 degrees F)
Mean annual precipitation--1270 millimeters (50 inches)

TAXONOMIC CLASS: Euic, thermic Typic Haplosaprists

TYPICAL PEDON: Coinjock mucky peat in an oligohaline marsh at about sea level (colors are for moist soil unless otherwise stated; electrical conductivity is 1:1 by volume solution mixture unless otherwise stated).

Oese--0 to 41 centimeters; very dark grayish brown (10YR 3/2) broken face and very dark brown (10YR 2/2) rubbed muck; 35 percent fibers, 20 percent rubbed; von Post H6; few very fine, medium, and coarse roots, and common fine roots; moderate sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; moderately acid (pH 6.0), strongly acid (pH 5.3) oxidized pH; clear boundary.

Oase1--41 to 110 centimeters; very dark brown (10YR 2/2) broken face and very dark brown (10YR 2/2) rubbed muck; 20 percent fibers, 8 percent rubbed; von Post H9; common very fine and fine roots; slight sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; moderately acid (pH 6.0), moderately acid (pH 5.9) oxidized pH; gradual boundary.

Oase2--110 to 166 centimeters; very dark grayish brown (2.5Y 3/2) broken face and very dark brown (10YR 2/2) rubbed muck; 15 percent fibers, 4 percent rubbed; von Post H10; common very fine and few fine roots; slight sulfurous odor; no color change with 3 percent hydrogen peroxide; moderate effervescence with 30 percent hydrogen peroxide; neutral (pH 7.0), moderately acid (pH 5.9) oxidized pH; clear boundary (combined thickness of the O horizons is 130 to 200 centimeters).

Cseg--166 to 200 centimeters; dark grayish brown (2.5Y 4/2) mucky silt loam; massive; moderately sticky, nonplastic; very fluid; 25 percent herbaceous plant fibers; slight sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; neutral (pH 7.0), extremely acid (pH 3.5) oxidized pH.

TYPE LOCATION: Currituck County, North Carolina; near the mouth of the Northwest River; approximately 2.3 kilometers (1.4 miles) south of the intersection of Middle Gibbs Road and Reeds Road, and approximately 4.6 kilometers (2.9 miles) east of the intersection of Tulls Creek Road and Wren Drive; USGS topographic quadrangle: Creeds.

Latitude--36.5162350
Longitude-- -76.0795260
Datum--WGS84
Coordinate source--From hand-held GPS

RANGE IN CHARACTERISTICS:
Depth to bedrock--Greater than 200 centimeters
Soil moisture regime--Peraquic
Manner of failure / fluidity class--Slightly fluid to very fluid throughout the mineral horizons
Wood fragments--0 to 14 percent below 100 centimeters
Sulfurous odor--None to strong throughout
Soil reaction--Moderately acid to slightly alkaline throughout (pH 5.6 to 7.8)
Oxidized reaction--Strongly acid to moderately acid in the organic horizons (pH 5.1 to 6.0) and ultra acid to extremely acid in the mineral horizons (pH < 3.5 to 4.4)
Depth to hypersulfidic / sulfidic materials--Greater than 100 centimeters
Electrical conductivity (1:1 soil to water solution)--0.6 to 3.1 dS/m
Salinity class--Nonsaline to very slightly saline
Total soil organic carbon stock 0 to 100 centimeters--39 to 42 kg m-2
Total soil organic carbon stock 0 to 200 centimeters--66 to 81 kg m-2

Oese horizon:
Hue--7.5YR or 10YR
Value--2 to 3
Chroma--1 or 2
Texture--Mucky peat
Von Post humification scale--H4 to H6
Organic carbon density--24 to 71 kg m-3

Oase horizon:
Hue--5YR to 2.5Y
Value--2 to 4
Chroma--1 to 3
Texture--Muck
Von Post humification scale--H7 to H10
Organic carbon density--24 to 71 kg m-3

Oise horizon (where present):
Hue--7.5YR or 10YR
Value--2.5 or 3
Chroma--2 or 3
Texture--Peat
Von Post humification scale--H1 to H3
Organic carbon density--24 to 71 kg m-3

Aseg, ACseg, or CAg horizons (where present):
Hue--10YR or 2.5Y
Value--3 or 4
Chroma--1 to 3
Texture--Fine sandy loam, loam, silt loam, or their mucky analogs
Organic carbon density--25 to 40 kg m-3

Cseg horizon:
Hue--10YR to 5Y
Value--3 or 4
Chroma--1 or 2
Texture--Silt loam or mucky silt loam
Organic carbon density--13 to 40 kg m-3

COMPETING SERIES:
These are the Hobonny, Joice, Longshoal, and Rindge soils.
Hobonny soils--formed in herbaceous and woody organic materials and are directly influenced by freshwater.
Joice soils--receive 380 to 510 millimeters (15 to 20 inches) of precipitation per year, lack sulfurous odors, have electrical conductivities between 15 and 48 dS/m, and lack hypersulfidic materials below 100 centimeters.
Longshoal soils--formed in herbaceous and woody organic materials over fluviomarine deposits and are in estuaries with salinities between 5 and 30 parts per thousand.
Rindge soils--receive 305 to 510 millimeters (12 to 20 inches) of precipitation per year, lack sulfurous odors, lack hypersulfidic materials below 100 centimeters, and are often used for cultivating crops (have Oap horizons).

GEOGRAPHIC SETTING:
Landscape--Southeast coastal plain estuaries
Landform--Oligohaline marshes along rivers and creeks
Parent material--Herbaceous organic material over loamy estuarine deposits
Slope--0 to 1 percent
Elevation--0 to 1 meter
Water salinity range--0.5 to 5 parts per thousand
Frost free period--230 to 360 days

GEOGRAPHICALLY ASSOCIATED SOILS:
These are the Coratank, Goosecastle, and Pocaty soils.
Coratank soils--have organic horizons that are less than 130 centimeters thick, on similar landforms.
Goosecastle soils--formed in herbaceous organic materials over fluviomarine deposits.
Pocaty soils--contain hypersulfidic materials within 100 centimeters of the soil surface, on similar landforms.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--Very poorly drained
Saturated hydraulic conductivity--Moderately high to high
Soil moisture regime--Peraquic
Flooding--Very frequent, for very brief durations. The soils are flooded by wind tides. Coinjock soils are not normally subject to inundation from lunar tides.

USE AND VEGETATION:
Major uses--Coinjock soils are used mainly as wetland wildlife habitat.
Typical vegetation--Dominantly needlegrass rush (Juncus roemerianus), Olney's three square (Schoenoplectus americanus), big cordgrass (Spartina cynosuroides), and narrowleaf cattail (Typha angustifolia). Areas transitional to higher elevations have scattered eastern baccharis (Baccharis halimifolia), waxmyrtle (Myrica cerifera), and black willow (Salix nigra) shrubs. In some areas, much of the native vegetation has been overtaken by invasive common reed (Phragmites australis).

DISTRIBUTION AND EXTENT:
General area--Coastal plain estuaries in North Carolina and Virgina
Land Resource Regions--T - Atlantic and Gulf Coast Lowland Forest and Crop Region
MLRA(s)--153B
Extent--Small

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Special Projects Region

SERIES ESTABLISHED: City of Virginia Beach, Virginia, 2026

REMARKS:
The series is named after the town of Coinjock, NC and Coinjock Bay. Coinjock soils were previously mapped as Pocaty and Currituck in Virginia and North Carolina soil surveys, respectively.

Diagnostic horizons and other diagnostic soil characteristics recognized in this pedon are (Keys to Soil Taxonomy, Thirteenth Edition, 2022):
Hemic soil materials--The zone from 0 to 41 centimeters has a fiber content after rubbing that is between one-sixth and two-fifths of the original soil volume.
Sapric soil materials--The zone from 41 to 166 centimeters has a fiber content after rubbing that is less than one-sixth of the original soil volume.
Hyposulfidic materials--The zone from 110 to 166 has an initial pH that decreases by 1 or more units but remains at a value of 4.0 or more after 16 weeks of moist aerobic incubation.
Fluidity--The zone from 166 to 200 centimeters has a fluidity class of very fluid.
Hypersulfidic materials--The zone from 166 to 200 centimeters has a pH of 4.0 or less after 16 weeks of moist aerobic incubation.
Peraquic feature--Zero or positive water potential at or near the soil surface.

NASIS User Site and Pedon ID: 2025NC053113
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National Cooperative Soil Survey
U.S.A.