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Nagunt Subaqueous Soils

Soil Map Unit Description from the RI Soil Survey Report (2010 Update)

WNa0: Nagunt sand, 0 to 1 meter water depth (2010 Update for the RI Coastal Zone Soil Survey Phase I - please download the latest copy of the spatial data).

This subaqueous soil is found on washover fan flats in coastal lagoons along the south shore of Washington County, RI. Areas are irregular or linear in shape found along the lagoonal side of barrier islands. Areas range in size from 3 to 117 hectares (9 to 290 acres). Slope ranges from 0 to 3 percent.

Typically, this soil has a non-fluid, gray, fine sand surface and a stratified sandy subsoil derived from marine or estuarine material that has been washed over a barrier in large storm events. Buried surface horizons with greater amounts of organic matter and sulfides are often identified. Up to 5 percent gravel and up to 35 percent shell fragments may be found throughout the soil profile, including on the surface.

This soil is permanently submerged beneath up to 1 meter of salt or brackish water but may be exposed at extreme low tides. All horizons have a slightly alkaline pH and may develop an acidic pH after oxidation. These soils contain sulfidic materials within the upper 100 cm, usually within horizons containing greater amounts of organic matter.

Included with this soil are small areas of Fort Neck soils in low energy areas where fine material may accumulate on the soil surface. Massapog soils may be found flood tidal delta flats in coastal lagoons that do not have sulfidic materials within 100 cm of the soil surface. Included areas make up 15 percent of this map unit.

The Nagunt soils provide habitat for quahogs, scallops, and periwinkles and are commonly used in recreational and commercial shellfish operations and aquaculture.

Link to Official Series Description - Nagunt | Soil Profile Photo of Nagunt Series

UPDATE: The Coastal Zone of Rhode Island is currently being updated and re-mapped, for more information on this update visit: www.mapcoast.org


WNs1: Nagunt sand, sloping phase, 1 to 2 meter water depth (2010 Update for the RI Coastal Zone Soil Survey Phase I - please download the latest copy of the spatial data).

This subaqueous soil is found on washover fan slopes in coastal lagoons along the south shore of Washington County, RI. Areas are linear in shape found along the lagoonal side of barrier islands. Areas range in size from 0.5 to 56 hectares (1 to 140 acres). Slope ranges from 3 to 10 percent.

Typically, this soil has a non-fluid, gray, fine sand surface and a stratified sandy subsoil derived from marine or estuarine material that has been washed over a barrier in large storm events. Buried surface horizons with greater amounts of organic matter and sulfides are often identified. Fluid marine silts may occur deeper in the profile where washover sands have covered an existing Pishagqua soil on a lagoon bottom. Up to 5 percent gravel and up to 35 percent shell fragments may be found throughout the soil profile including the surface.

This soil is permanently submerged beneath 1 to 2 meters of salt or brackish water. All horizons have a slightly alkaline pH and may develop an acidic pH after oxidation. These soils contain sulfidic materials within the upper 100 cm, usually within horizons containing greater amounts of organic matter.

Included with this soil are small areas of Fort Neck soils in low energy areas where fine material may accumulate on the soil surface. Massapog soils may be found flood tidal delta flats in coastal lagoons that do not have sulfidic materials within 100 cm of the soil surface. Pishagqua soils may also be included in this map unit where the washover fan slope grades into the lagoon bottom. Included areas make up 15 percent of this map unit.

This soil is an important habitat for eelgrass (Zostera marina) and often has 50 percent or more eelgrass cover.

 

Link to Official Series Description - Nagunt | Soil Profile Photo of Nagunt Series

UPDATE: The Coastal Zone of Rhode Island is currently being updated and re-mapped, for more information on this update visit: www.mapcoast.org

 

WNd: Nagunt sand, dredged phase, 2 to 5 meter water depth (2010 Update for the RI Coastal Zone Soil Survey Phase I - please download the latest copy of the spatial data).

This subaqueous soil is found on washover fan flats in coastal lagoons in areas that have been dredged for navigation. Areas are irregular or linear in shape found along the lagoonal side of barrier islands. Areas range in size from 0.5 to 10 hectares (1 to 25 acres). Slope ranges from 0 to 3 percent but greater than 15 percent along the edges of the dredge footprint.

Typically, this soil has a non-fluid, gray, sandy surface and a sandy subsoil derived from marine or estuarine material that has been washed over a barrier in large storm events. Up to 10 percent gravel and up to 35 percent shell fragments may be found throughout the soil profile.

This soil is permanently submerged beneath more than 2 meters of salt or brackish water but may be exposed at extreme low tides. All horizons have a slightly alkaline pH and may develop an acidic pH after oxidation. These soils contain sulfidic materials within the upper 100 cm, usually within horizons containing greater amounts of organic matter.

Included with this soil are small areas of Fort Neck soils in low energy areas where fine material may accumulate on the soil surface. Massapog soils may be found flood tidal delta flats in coastal lagoons that do not have sulfidic materials within 100 cm of the soil surface. Anguilla and Napatree soils may be found where soils have been dredged down to the glacial material below. Included areas make up 15 percent of this map unit.

The Nagunt soils provide habitat for quahogs, scallops, and periwinkles and are commonly used in recreational and commercial shellfish operations. This map unit may support eelgrass (Zostera marina).

 

Link to Official Series Description - Nagunt | Soil Profile Photo of Nagunt Series

UPDATE: The Coastal Zone of Rhode Island is currently being updated and re-mapped, for more information on this update visit: www.mapcoast.org