LOCATION NAPATREE CT+RI

Established Series
Rev. MKP-JDT-DCP
05/2024

NAPATREE SERIES

The Napatree series consists of very deep, subaqueous soils in submerged headlands, mainland coves, and submerged mainland beaches in lagoons, coves, and bays adjacent to glaciated uplands with numerous boulders and stones. The Napatree soils are formed in sandy marine deposits overlying submerged terrestrial loess or till deposits. These soils are permanently submerged beneath 10 through 200 cm of tidal estuarine water. Slope ranges from 0 to 15 percent, mean annual air temperature is about 10 degrees C, and mean annual precipitation is about 1295 mm.

TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, mesic Aeric Haplowassents

TYPICAL PEDON: Napatree gravelly sand on a south facing, extremely bouldery 2 percent slope in a submerged headland under 1.6 m of estuarine water. Tidal range is 80 cm. (Colors are for moist soil).

Ase -- 0 to 20 cm; black (N 2.5/) gravelly sand; single grain; nonfluid; many fine distinct olive brown (2.5Y 4/4) masses of iron accumulation; 10 percent gravels; 5 percent shell fragments; sulfurous odor; strongly saline (28 ppt); neutral (pH 6.9); very strongly acid (pH 5.0) after 8 weeks; clear boundary. (5 to 30 cm thick.)

C1 -- 20 to 32 cm; olive brown (2.5Y 4/3) loamy sand; single grain; nonfluid; 10 percent gravels; strongly saline; neutral (pH 6.9); moderately acid (pH 6.0) after 8 weeks; clear boundary.

C2 -- 32 to 45 cm; olive brown (2.5Y 4/3) gravelly sandy loam; massive; nonfluid; common fine faint olive brown (2.5Y 4/4) masses of iron accumulation; 18 percent gravels; strongly saline; neutral (pH 7.2); slightly acid (pH 6.2) after 8 weeks; abrupt boundary. (Combined thickness of the C horizons is 20 to 35 cm thick.)

2Cg1 -- 45 to 58 cm; dark grayish brown (2.5Y 4/2) silt loam; massive; nonfluid; many fine distinct gray (5Y 5/1) areas of iron depletion; strongly saline; slightly alkaline (pH 7.4); neutral (pH 6.8) after 8 weeks; clear boundary.

2Cg2 -- 58 to 65 cm; gray (5Y 5/1) silt loam; massive; nonfluid; common fine distinct olive (5Y 5/4) masses of iron accumulation; strongly saline; slightly alkaline (pH 7.4); neutral (pH 6.8) after 8 weeks; abrupt boundary. (Combined thickness of the 2Cg horizons is 0 to 60 cm thick.)

3Cg3 -- 65 to 120 cm; dark grayish brown (2.5Y 4/2) very gravelly loamy sand; single grain; nonfluid; 40 percent gravels; strongly saline; neutral (pH 7.2); neutral (pH 6.9) after 8 weeks.

TYPE LOCATION: New London County, Connecticut; located about 4910 feet southeast of the Barn Island boat launch and 7260 feet southwest of the intersection of Green Haven Road and Osbrook Point Road, just south of Perch Island. USGS Watch Hill, CT topographic quadrangle, Latitude 41 degrees, 20 minutes, 26.3 seconds N. and Longitude 71 degrees, 53 minutes, 15.1 seconds W., WGS 84.

RANGE IN CHARACTERISTICS: The soils are permanently submerged except for some of the surface boulders that are exposed to the air during low tides. All horizons have a pH of neutral through moderately alkaline and an oxidized pH of ultra acid through neutral. Soil has a 5:1 salinity greater than 0.2 dS/m throughout the profile.

The Ase and ACse horizon, when present, has hue of neutral through 5GY, 5Y, or 10YR, value of 2.5 through 7, and chroma of 0 through 2. It is typically sand, loamy sand, loamy coarse sand, coarse sand, or sandy loam with gravelly analogs. Thin horizons of fine sandy loam, loam, or silt loam may be present. Consistence is nonfluid. Gravel content is 0 through 10 percent. Shell fragment content is 0 through 10 percent. Redoximorphic features may be present.

The C horizon has hue of 2.5Y, 5Y, or 10Y, value of 3 through 7, and chroma of 1 through 4. Textures are similar to Ase and ACse horizons. Consistence is nonfluid. Gravel content is 0 through 20 percent.

The 2Cg and 3Cg horizons and 2C and 3C horizons, when present, have hue of 10YR, 10Y, 2.5Y or 5Y, value of 4 or 5, and chroma of 1 through 6. They are typically silt loam, fine sandy loam, sandy loam, loamy sand, loamy coarse sand, or coarse sand including gravelly or very gravelly analogs. Consistence is nonfluid. Gravel content is 0 through 40 percent. Redoximorphic features may be present.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: The Napatree soils are permanently submerged with salt or brackish water in submerged headlands, mainland coves, and submerged mainland beaches in bays, coves and lagoons adjacent to glaciated uplands with numerous boulders and stones. The surface boulders are often exposed to the air at low tides. Slope ranges from 0 through 2 percent. The soils formed in submerged terrestrial soils with a capping of sandy marine deposits and can be found up to 5 meters deep under water. The potential for submarine fresh ground water discharge zones are high given the geomorphic position and high through very high saturated hydraulic conductivity.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anguilla, Billington, Fort Neck, Pishagqua, and Wequetequock soils. The Anguilla soils are adjacent to landscapes dominated by outwash material in mainland coves and mainland submerged beaches, and have a particle-size class family of sandy and sulfidic materials in the soil profile. Fort Neck (T) soils have fluid, sulfidic materials at the soil surface. Billington, Wequetequock, and Pishagqua soils are in mainland coves and lagoon bottom landscapes and have fluid, sulfidic materials in the soil profile.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Subaqueous, peraquic moisture regime, and high or very high saturated hydraulic conductivity. Soil is permanently submerged with salt or brackish water.

USE AND VEGETATION: These soils are used for recreation and aquatic habitat. Shellfish cultivation, which includes lobsters, hard-clams, and oysters, is very important in these soils. In addition fishing is commonplace and the species found in the area are smelt, small cod, flounder, scup, menhaden, and white perch. Some areas are vegetated with native floating algae and rooted vegetation such as eelgrass (Zostera marina). Vegetative cover ranges from 0 through 15 percent.

DISTRIBUTION AND EXTENT: New London County, Connecticut, and Rhode Island. MLRA 144A and 149B. The soils of this series are not extensive (total extent is about 1300 acres).

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: SPECIAL PROJECTS OFFICE

SERIES ESTABLISHED: New London County, Connecticut, 2010.

REMARKS: Diagnostic horizons and features in this pedon include:
1. Sulfidic materials - zone from 0 to 20 cm (Ase horizon)
2. Peraquic feature - positive soil water potential (permanently submerged) at the soil surface. (under 1.6 m of water at the time of coring).
3. Particle-size control section - the zone from 25 to 100 cm (part of C1, C2, 2Cg1, 2Cg2, and part of 3Cg3 horizons).
4. Aeric feature - chroma of 3 in the zone from 20 to 45 cm (C1 and C2 horizons).
5. Lithologic discontinuity - sandy marine deposits overlying loamy eolian deposits at 45 cm (2Cg1 horizon) and sandy till at 65 cm (3Cg3 horizon).

ADDITIONAL DATA:
This pedon was sampled as 2005CT011003-LN. Support pedons used to develop this series include S2009RI009005-QP, S2006RI009012-QP , S2008RI009019-WP, and S2008RI009018-WP (all sampled by the University of Rhode Island).

National Cooperative Soil Survey
U.S.A.