LOCATION MASSAPOG RI+CT

Established Series
Rev. MKP-JDT
05/2024

MASSAPOG SERIES

The Massapog series consists of very deep, subaqueous soils permanently submerged beneath 10 through 150 cm of tidal estuarine water on flood tidal delta flats in coastal lagoons and bays. Massapog soils are formed in sandy marine and estuarine sediments transported by flood tidal currents. Slope ranges from 0 through 2 percent, mean annual air temperature is about 10 degrees C., and mean annual precipitation is about 1295 mm.

TAXONOMIC CLASS: Mixed, mesic Fluventic Psammowassents

TYPICAL PEDON: Massapog sand on a north facing, nearly level slope on a flood tidal delta under 0.5 meters of tidal estuarine water. Tidal range is 100 cm. (Colors are for moist soil).

Cg1 -- 0 to 9 cm; light olive gray (5Y 6/2) fine sand, light greenish gray (10Y 7/1) dry; single grain; nonfluid; strongly saline; moderately alkaline (pH 8.0); slightly alkaline (pH 7.6) after 8 weeks; abrupt boundary.

Cg2 -- 9 to 48 cm; light gray (5Y 7/2) fine sand; single grain; nonfluid; stongly saline; moderately alkaline (pH 7.9); slightly alkaline (pH 7.7) after 8 weeks; gradual boundary.

Cg3 -- 48 to 65 cm; gray (5Y 6/1) fine sand; single grain; nonfluid; strongly saline; moderately alkaline (pH 7.9); slightly alkaline (pH 7.8) after 8 weeks; gradual boundary.

Cg4 -- 65 to 100 cm; gray (5Y 6/1) fine sand; single grain; nonfluid; strongly saline; slightly alkaline (pH 7.8); slightly alkaline (pH 7.8) after 8 weeks; gradual boundary. (Combined thickness of Cg horizons 30 to 100 cm thick.)

CA -- 100 to 115 cm; very dark gray (5Y 3/1) fine sand; single grain; nonfluid; strongly saline; moderately alkaline (pH 8.1); slightly alkaline (pH 7.8) after 8 weeks; clear boundary. (0 to 30 cm thick.)

Ab -- 115 to 150 cm; black (N 2.5/) fine sand; massive; nonfluid; strongly saline; few medium shell fragments, common medium and coarse plant fragments; moderately alkaline (pH 8.4); slightly alkaline (pH 7.4) after 8 weeks; clear boundary. (0 to 35 cm thick.)

C'g -- 150 to 161 cm; black (5Y 2.5/1) fine sand; single grain; nonfluid; strongly saline; few fine and medium macroalgal fragments; strongly alkaline (pH 8.8); slightly alkaline (pH 7.7) after 8 weeks; clear boundary. (10 to 85 cm thick.)

A'b -- 161 to 181 cm; black (N 2.5/) fine sand; single grain; nonfluid; strongly saline; strongly alkaline (pH 8.8); slightly alkaline (pH 7.6) after 8 weeks; common fine and medium plant fragments; clear boundary. (0 to 30 cm thick.)

C''g -- 181 to 200 cm; black (5Y 2.5/1) fine sand; single grain; nonfluid; strongly saline; 5 percent fine and medium shell fragments; strongly alkaline (pH 8.7); slightly alkaline (pH 7.7) after 8 weeks.

TYPE LOCATION: Washington County, Rhode Island. Located in Quonochontaug Pond about 1400 feet northwest of the Quonochontaug breachway boat launch, about 2100 feet east of intersection of Wagner and Rossini Roads. USGS Quonochontaug, RI topographic quadrangle, Latitude 41 degrees, 20 minutes, 18 seconds N. and Longitude 71 degrees 43, minutes, 36 seconds W., NAD 1983.

RANGE IN CHARACTERISTICS: The soils are permanently submerged or exposed only during spring low tides. Gravel content is 0 through 5 percent throughout the profile. Shell content is 0 through 5 percent throughout the profile. Consistence is nonfluid throughout. All horizons have a pH of neutral through strongly alkaline and an oxidized pH of extremely acid through moderately alkaline. Soil has a 5:1 salinity greater than 0.2 dS/m throughout the profile. After drying, it is common for many of these soils to develop 5Y 5/4 mottles throughout the matrix.

The Cg horizons have hue of 10Y, 5Y, or is neutral, value of 2.5 through 7, and chroma of 0 through 2. Textures range from fine sand through sand.

The CA or AC horizons have hue of 10Y, 5Y, 10GY, or is neutral, value of 3 through 4, and chroma of 0 or 1.Textures range from loamy fine sand through sand.

Some pedons have multiple buried horizon sequences representing multiple buried surfaces through time. The Ab and A'b horizons have hue of 2.5Y, 5Y, or is neutral, value of 2.5 through 6, and chroma of 0 or 1. Textures range from loamy fine sand through sand.

COMPETING SERIES: This is the Rhodesfolly series. Rhodesfolly soils are found on washover fan flats in open bays and have a coarser particle size consisting of sands and coarse sands with greater than 5 percent gravels in some horizons.

GEOGRAPHIC SETTING: Massapog soils are permanently submerged under 0 through 1.5 meters of salt or brackish water on flood tidal delta flats in coastal lagoons and bays. Slope ranges from 0 through 2 percent. The soils formed in sandy estuarine and marine sediments.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Anguilla, Marshneck, Pishagqua, Nagunt, and Napatree soils. Marshneck soils are found on flood tidal delta slopes in coastal lagoons and have sulfidic materials and particle sizes finer than loamy fine sand within the 100 cm of the soil surface. Pishagqua soils are found on low energy lagoon bottoms and have greater than 100 cm of highly fluid, sulfidic, silt loam at the soil surface. Nagunt soils are found on washover fan flats and slopes in coastal lagoons and contain sulfidic materials within 100 cm of the soil surface. Napatree and Anguilla soils are on submerged headlands and submerged mainland beaches and have a lithologic discontinuity within 100 cm of the soil surface.

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

USE AND VEGETATION: This soil supports submerged aquatic vegetation and aquatic habitats. Areas of this soil are utilized for shell fishing and recreational uses. Some areas are vegetated with native rooted eelgrass (Zostera marina). Vegetative cover ranges from 0 through 20 percent.

DISTRIBUTION AND EXTENT: New London County, Connecticut, and Rhode Island. MLRA 144A. The soils of this series are not extensive (total extent is about 500 acres (200 hectares)).

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

SERIES ESTABLISHED: Washington County, Rhode Island, 2010.

REMARKS: This subaqueous series is being proposed in areas previously mapped as water in the Rhode Island and Connecticut Soil Surveys.

Diagnostic horizons and features in this pedon include:
1. Peraquic feature - positive soil water potential (permanently submerged) at the soil surface (under 0.6 m of water at the time of coring).
2. Reduced conditions - the zone from 0 to 195 cm.
3. Fluventic Feature - An irregular decrease in organic carbon from a depth of 25 cm to a depth of 125 cm.
4. Particle-size control section - zone from 25 to 100 cm (Cg2, Cg3, Cg4, and CA horizons).
5. Psammowassents - less than 35 percent (by volume) rock fragments and a texture class of loamy fine sand or coarser in all layers within the particle-size control section.

ADDITIONAL DATA: Pedon sample RI009-2006-013-QP in Washington County, Rhode Island, by University of Rhode Island. Additional pedons used to determine ranges include RI009-2009-002-QP, RI009-2009-001-QP, RI009-2009-007-PJ, and RI009-2007-010-PJ (Sampled by the University of Rhode Island).

National Cooperative Soil Survey
U.S.A.