LOCATION THALINECTES             MS

Established Series
RJK-RBT
10/2025

THALINECTES SERIES

MLRA(s)--152A
Depth class--Very deep
Drainage class--Subaqueous
Water depth range--0 to 300 centimeters
Parent material--Sandy marine deposits
Geomorphic location--Longshore bar
Slope range--0 to 2 percent
Mean annual air temperature--21 degrees C (70 degrees F)
Mean annual precipitation--1737 millimeters (68 inches)

TAXONOMIC CLASS: Siliceous, hyperthermic Fluventic Psammowassents

TYPICAL PEDON: Thalinectes fine sand on a north facing, nearly level slope on a longshore bar under 144 centimeters of estuarine water. Tidal range is 80 centimeters. (Colors are for moist soil unless otherwise stated).

Cg--0 to 4 centimeters; grayish brown (2.5Y 5/2) sand; single grain; loose, nonfluid, nonsticky, nonplastic; moderately acid (pH 6.0); clear boundary.

Cseg1--4 to 16 centimeters; dark gray (2.5Y 4/1) sand; single grain; loose, nonfluid, nonsticky, nonplastic; moderate sulfurous odor; positive color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; 1 percent shell fragments; neutral (pH 7.2), neutral (pH 6.8) oxidized pH; clear boundary.

Cseg2--16 to 39 centimeters; gray (2.5Y 5/1) sand; single grain; loose, nonfluid, nonsticky, nonplastic; slight sulfurous odor; slight effervescence with 30 percent hydrogen peroxide; neutral (pH 7.3), neutral (pH 7.1) oxidized pH; clear boundary.

Cseg3--39 to 61 centimeters; dark gray (10YR 4/1) sand; single grain; loose, nonfluid, nonsticky, nonplastic; slight effervescence with 30 percent hydrogen peroxide; 1 percent shell fragments; slightly alkaline (pH 7.5), neutral (pH 7.2) oxidized pH; gradual boundary.

Cseg4--61 to 146 centimeters; dark gray (2.5Y 4/1) sand; single grain; loose, nonfluid, nonsticky, nonplastic; slight efferevescence with 30 percent hydrogen peroxide; slightly alkaline (pH 7.8), slightly alkaline (pH 7.5) oxidized pH; gradual boundary.

Cseg5--146 to 200 centimeters; 60 percent dark gray (10YR 4/1) and 40 percent gray (10YR 5/1) sand; single grain; loose, nonfluid, nonsticky, nonplastic; slight efferevescence with 30 percent hydrogen peroxide; moderately alkaline (pH 8.4), moderately alkaline (pH 7.9) oxidized pH.

TYPE LOCATION: Harrison County, Mississippi; from the west most point on Cat Island, approximately 1.08 kilometers Northwest and approximately 420 meters Northeast of the lighthouse on the western most portion of Cat Island. USGS topographic quadrangle: Isle Au Pitre, LA.

Latitude--30.233537
Longitude-- -89.158520
Datum--WGS84
Coordinate source--Manually entered from GPS

RANGE IN CHARACTERISTICS:
Depth to bedrock--greater than 200 centimeters
Soil moisture--Continuously inundated
Reaction throughout--Moderately acid to strongly alkaline (pH 5.6 to 9.0)
Oxidized reaction--Very strongly acid to moderately alkaline (4.5 to 8.4)
Electrical conductivity (1:5 soil-water, throughout)--0.6 dS/m or greater
Manner of failure throughout--Nonfluid
Shell fragments throughout--0 to 50 percent
Total soil organic carbon stock to 200 centimeters--3 to 14 kg m-2

CAseg horizon (where present):
Hue---10YR to 7.5YR
Value--5 or 6
Chroma--1 or 2
Texture--fine sand or coarser with shelly analogs

Cg horizon:
Hue--2.5Y to 10Y or neutral
Value--2.5 to 5
Chroma--0 to 2
Texture--loamy sand or coarser with shelly analogs
Organic carbon density--0.01 to 0.15 kg m-3

Cseg horizon:
Hue--10YR to 5Y
Value--4 to 7
Chroma--1 or 2
Texture--fine sand or sand with shelly analogs
Thickness--0 to 78 centimeters thick
Organic carbon density--0.01 to 0.15 kg m-3

CAg or C/A (where present):
Hue--5Y or 2.5Y
Value--3 to 6
Chroma--0 to 2
Texture--loamy fine sand or coarser with shelly analogs
Thickness--0 to 29 centimeters

Asegb horizon (where present):
Hue--7.5YR to 10Y or is neutral
Value--2.5 or 3
Chroma--0 to 2
Texture--loamy fine sand or coarser
Organic carbon density--0.04 to 0.20 kg m-3

C'seg horizon (where present):
Hue--5Y
Value--2 to 5
Chroma--0 to 2
Texture--sandy loam or coarser
Organic carbon density--0.01 to 0.15 kg m-3

COMPETING SERIES:
Broadaxe soils--are on submerged wave-cut platform landforms and often contain former preserved spodic fluviomarine diagnostic soil horizons
Mullet soils--are on washover-fan flat landforms within estuaries and lagoons and often have hues on the gley pages

GEOGRAPHIC SETTING:
Parent material--Sandy marine deposits
Landscape--Gulfs, bays, and coastal estuaries
Landform--Longshore bars, barrier coves
Slope--0 to 2 percent
Mean annual precipitation--1264 to 1737 millimeters (50 to 68 inches)
Mean annual air temperature--19 to 21 degrees C (66 to 70 degrees F)
Water salinity range--18 to 30 parts per thousand

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Handsboro, Kesson, and St. Lucie soils.
Handsboro soils--are in tidal salt marshes and have thick organic soil horizons throughout
Kesson soils--are very poorly drained, often have eolian origins, and are not permanently submerged
St. Lucie soils--are excessively drained on adjacent dunes, have eolian origins and are much higher on the landscape

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--Subaqueous
Saturated hydraulic conductivity--High or very high
Soil moisture regime--Peraquic
Soil is permanently inundated with saline and brackish water with considerable tidal exchange which limits the development of sulfidic soil material.

USE AND VEGETATION:
Major uses--Supports benthic aquatic habitat and is used for fishing and recreational and commercial shellfish harvesting
Native vegetation--Native algae and eelgrass (Zostera marina); vegetative cover ranges from 0 to 35 percent

DISTRIBUTION AND EXTENT:
General area--Located along the Alabama and Mississippi Gulf coast
Land Resource Regions--T - Atlantic and Gulf Coast Lowland Forest and Crop Region
MLRA(s)--MLRA 152A
Extent--Small

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

SERIES ESTABLISHED: Harrison County, Mississippi, 2025

REMARKS: This subaqueous series was previously mapped as water in Harrison County, Mississippi Soil Surveys. The name was selected by professors at Southern Mississippi University named after one of their research vessels. The name originates from a combination of Thalassia and Callinectes, the genera for turtlegrass and blue crab, respectively.

Diagnostic horizons and features in this pedon include:
Peraquic moisture regime--The zone from 0 to 200 centimeters has positive soil water potential (permanently submerged) at the soil surface (under 144 centimeters of salt water).
Particle-size control section--The zone from 0 to 100 centimeters (0 to 40 inches).
Fluventic Feature--soil organic carbon content of greater than 0.2 percent at a depth of 125 centimeters.

Taxonomic version--Keys to Soil Taxonomy, 13th edition (2022)

ADDITIONAL DATA:
Characterization data for the typical pedon, S2024MS047016 and additional pedon data, S2024MS047012 analyzed by North Carolina State University.
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National Cooperative Soil Survey
U.S.A.