LOCATION LIGHTHOUSE FL
Tentative Series
ARW
09/2026
LIGHTHOUSE SERIES
MLRA(s)--152A
Depth class--Very deep
Drainage class--Subaqueous
Water depth range--0 to 3 meters (0 to 10 feet)
Parent material--Loamy-skeletal lagoonal deposits
Geomorphic location--Shoals and reefs
Slope range--0 to 1 percent
Mean annual air temperature--21 degrees C (70 degrees F)
Mean annual water temperature--24 degrees C (75 degrees F)
TAXONOMIC CLASS: Loamy-skeletal, mixed, active, nonacid, hyperthermic Grossic Hydrowassents
TYPICAL PEDON: Lighthouse very shelly coarse sandy loam on a shoal under 2.0 meters of brackish water (colors are for moist soil unless otherwise stated; electrical conductivity is 1:5 by volume solution mixture unless otherwise stated).
Cseg1--0 to 35 centimeters; very dark grayish brown (2.5Y 3/2) very shelly coarse sandy loam; massive; nonsticky, nonplastic; very fluid; 55 percent shell fragments; no sulfurous odor; color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; saline (3.7 dS/m); strongly alkaline (pH 8.5), moderately alkaline (pH 8.2) oxidized pH; clear boundary
Cseg2--35 to 88 centimeters; very dark gray (5Y 3/1) extremely shelly sandy clay loam; massive; nonsticky, nonplastic; moderately fluid; 75 percent shell fragments; no sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; saline (4.5 dS/m); strongly alkaline (pH 8.5), moderately alkaline (pH 8.2) oxidized pH; clear boundary
Cseg3--88 to 131 centimeters; greenish black (10Y 2.5/1) very shelly sandy clay loam; massive; slightly sticky, nonplastic; moderately fluid; 55 percent shell fragments; moderate sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; saline (4.0 dS/m); moderately alkaline (pH 8.4), moderately alkaline (pH 8.2) oxidized pH; clear boundary
Cseg4--131 to 184 centimeters; very dark gray (5Y 3/1) extremely shelly sandy clay loam; massive; slightly sticky, nonplastic; moderately fluid; 70 percent shell fragments; slight sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; saline (3.8 dS/m); strongly alkaline (pH 8.5), moderately alkaline (pH 8.3) oxidized pH; clear boundary
Cseg5--184 to 226 centimeters; very dark greenish gray (10Y 3/1) shells; single grain; nonsticky, nonplastic; nonfluid; 95 percent shell fragments; strong sulfurous odor; no color change with 3 percent hydrogen peroxide; slight effervescence with 30 percent hydrogen peroxide; saline (4.9 dS/m); strongly alkaline (pH 8.5), moderately alkaline (pH 8.4) oxidized pH
TYPE LOCATION: Franklin County, Florida; East Bay; approximately 2.6kilometers ( miles) west of the terminus of Old Ferry Dock Road, approximately 5.9 kilometers (3.7 miles) east of the intersection of Avenue I and Water Street, and 9.9 kilometers (6.1 miles) north of Saint George Island Airport-14 Runway; USGS topographic quadrangle: Apalachicola, FL.
Latitude--29.735864
Longitude-- -84.927072
Datum--WGS84
Coordinate source--From hand-held GPS
RANGE IN CHARACTERISTICS:
Depth to bedrock--Greater than 200 centimeters
Fluidity class--Slightly fluid to very fluid in all horizons between 20 and 100 centimeters
Sulfurous odor--None to strong throughout
Soil reaction--Neutral to strongly alkaline throughout profile (pH 6.6 to 9.0)
Oxidized reaction--Neutral to moderately alkaline throughout profile (pH 6.6 to 8.4)
Electrical conductivity (1:5 soil to water solution)--2.5 to 6.0 dS/m throughout profile
Particle-size control section (weighted average):
Shell fragments--35 to 90 percent, by volume
Sand--40 to 75 percent
Clay--10 to 30 percent
Total soil organic carbon stock 0 to 100 centimeters--20 to 30 kg m-2
Total soil organic carbon stock 0 to 200 centimeters--40 to 70 kg m-2
Cseg or Cg (where present) horizons:
Hue--2.5Y to 10GY
Value--2.5 or 4
Chroma--1 or 2
Texture--sandy loam, coarse sandy loam, loam, sandy clay loam, clay loam, shells, and their shelly, very shelly, and extremely shelly analogs.
Organic carbon density--15 to 40 kg m-3
COMPETING SERIES:
There are no competing series in this family
GEOGRAPHIC SETTING:
Landscape--Bays and lagoons
Landform--Shoals and reefs
Parent material--Loamy-skeletal lagoonal deposits
Slope--0 to 1 percent
Water depth range--0 to 3 meters (0 to 10 feet) below mean sea level
Water salinity range--15 to 30 parts per thousand
Soil temperature--16 to 31 degrees C (61 to 88 degrees F)
Water temperature--18 to 28 degrees C (64 to 82 degrees F)
GEOGRAPHICALLY ASSOCIATED SOILS:
These are the
Apalachicola,
Dregs,
Dry Bar, and
Eastpoint soils.
Apalachicola soils--Formed on bay and lagoon bottoms from fine-loamy lagoonal deposits.
Dregs soils--Formed on dredge-deposit shoals from sandy human transported materials.
Dry Bar soils--Formed on shoals and reefs from sandy-skeletal lagoonal deposits and are nonfluid throughout.
Eastpoint soils--formed on submerged wave-cut platforms from sandy lagoonal deposits and have hyposulfidic materials.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--Subaqueous
Saturated hydraulic conductivity--Moderately high to high
Soil moisture regime--Peraquic
Soil is continuously inundated by brackish or salt water
USE AND VEGETATION:
Major uses--Commercial uses include production and harvesting Eastern oysters (Crassostrea virginica). Recreational uses include oyster harvesting and fishing.
Typical vegetation--Vegetation is rarely observed on Lighthouse soils due to the prevalence of active and inactive oyster shell beds occurring on the surface.
DISTRIBUTION AND EXTENT:
General area--Brackish and saltwater shoals and reefs along the Gulf.
Land Resource Regions--T - Atlantic and Gulf Coast Lowland Forest and Crop Region
MLRA(s)--152A
Extent--Moderate
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Special Projects Office
SERIES ESTABLISHED: Franklin County, Florida, 2026
REMARKS:
Typical Pedon Taxonomic Features:
Reduced matrix--The zone from 0 to 226 centimeters has a soil color matrix with a chroma of 2 or less.
Fluidity--The zone from 0 to 184 has a fluidity class of slightly fluid to very fluid.
Peraquic feature--Zero or positive soil water potential at the soil surface (permanently submerged).
Taxonomic Version: Keys to Soil Taxonomy, Thirteenth Edition, 2022
Other: The series is named after Lighthouse Bar, a historic oyster reef where first observed. Lighthouse soils were previously mapped as water in Florida soil surveys.
NASIS User Site and Pedon ID: S2024FL037021
National Cooperative Soil Survey
U.S.A.