LOCATION GREAT BAY NH

Established Series
Revised DCP-MV-JVG
04/2023

GREAT BAY SERIES

The Great Bay series consists of very deep, subaqueous soils in bays and coves within estuaries of the northeast. The Great Bay soils are formed in silty estuarine deposits overlying clayey glaciomarine deposits. These soils are in intertidal areas or are continuously inundated in salt or brackish water. Slope ranges from 0 to 5 percent. The mean annual temperature is about 10 degrees C, and the mean annual precipitation is about 1295 millimeters.

TAXONOMIC CLASS: Fine-silty over clayey, mixed, subactive, nonacid, mesic Fluventic Sulfiwassents

TYPICAL PEDON: Great Bay silt loam in a cove continuously inundated with estuarine water. Tidal range is approximately 2.7 meters. (Colors are for moist soil).

Ase--0 to 7 centimeters; black (N 2.5/) silt loam; massive; very fluid; 10 percent channers, 2 percent shell fragments; slight sulfurous odor; slightly alkaline (pH 7.4); strongly acid (pH 5.1) after 16 weeks moist incubation; clear boundary. (6 to 29 centimeters thick.)

Cseg--7 to 54 centimeters; very dark greenish gray (10Y 3/1) silt loam; massive; moderately fluid; 5 percent shell fragments; slight sulfurous odor; slightly alkaline (pH 7.7); extremely acid (pH 3.6) after 16 weeks moist incubation; 2 percent plant fibers; clear boundary.

2Cg1--54 to 62 centimeters; dark gray (N 4/) silty clay; massive; firm; nonfluid; moderately alkaline (pH 8.2); very strongly acid (pH 4.6) after 16 weeks of moist incubation; clear boundary.

2Cg2--62 to 150 centimeters; dark grayish olive (10Y 4/2) silty clay; massive; firm; nonfluid; many coarse distinct dark yellowish brown (10YR4/4) masses of oxidized iron, common fine distinct dark reddish brown (5YR 3/2) masses of oxidized iron; neutral (pH 7.0); moderately alkaline (pH 8.1) after 16 weeks of moist incubation; few very thin lenses of fine sand.

TYPE LOCATION: Rockingham County, New Hampshire; located about 0.5 kilometers north of Fox Point Road and 0.8 kilometers west of Great Bay Marine boat launch in Broad Cove. USGS Portsmouth, NH topographic quadrangle, Latitude 41 degrees, 6 minutes, 51.5 seconds N. and Longitude 70 degrees, 50 minutes, 39.2 seconds W., WGS 84.

RANGE IN CHARACTERISTICS: The soils are continuously inundated or may be exposed to the atmosphere during periods of low tide. Depth to lithologic discontinuity (glaciomarine deposits) is less than 1 meter. Initial pH ranges from neutral through moderately alkaline, and oxidized pH ranges from ultra-acid through neutral. Soil has a 5:1 salinity greater than 0.6 dS/m throughout the profile. Sulfur odor ranges from strong to non-detectable.

The Ase horizon, and ACse where present, has hue of 2.5Y, 2.5GY, 5GY, 5Y, 10Y, or 10YR, value of 2 through 5, and chroma of 0 through 2; or is neutral with value of 2 through 5. Texture is silt loam. Thin horizons of fine sandy loam, loam, very fine sandy loam or sand occur in some pedons. Consistence is typically very fluid. Gravel content is 0 through 10 percent. Shell fragment content is 0 through 40 percent. Herbaceous plant fibers and wood fragments may be present.

The Cseg horizon, and Cg where present, has hue of 5GY, 5Y, or 10Y, value of 3 or 4, and chroma of 1. Texture is typically silt loam, but silty clay loam may be present. Thin horizons of fine sandy loam, loam, very fine sandy loam or sand occur in some pedons. Consistence is typically moderately fluid. Gravel content is 0 through 10 percent. Shell fragment content is 0 through 40 percent. Herbaceous plant fibers and wood fragments may be present.

The 2Cg horizon, and 2Cse where present, have hue of 5BG, 5PB, 5G, 5GY, 5Y, 10BG, or 10Y, value of 2.5 through 5, and chroma of 0 through 2; or is neutral with value of 2.5 through 5. They are typically silty clay loam or silty clay, however, may include silt loam and thin strata of loamy very fine sand or fine sand. Consistence is nonfluid and often firm. Gravel content is 0 through 2 percent. Redoximorphic features may be present, some pedons have angular blocky structure.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Great Bay soils are continuously inundated or are in the intertidal zone of bays, coves, and estuaries in brackish or salt water, along coastal areas of New England. Great Bay soils formed in silty estuarine deposits overlying clayey glaciomarine deposits, primarily the Presumpscot Formation. Slope ranges from 0 through 2 percent.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Billington, Marshneck, and Pishagqua soils. Billington soils are in bays and coves with mineral estuarine deposits overlying organic deposits. Marshneck soils are in higher energy areas of estuarine deposits with less clay and more sand in the profile. Pishagqua soils are in low energy areas with more than 1 meter of fluid estuarine silts and clays.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Subaqueous drainage class, peraquic moisture regime, and low or very low saturated hydraulic conductivity. The soil is continuously inundated with salt or brackish water.

USE AND VEGETATION: These soils are used for recreation, aquatic habitat, and shellfish aquaculture. Eelgrass (Zostera marina) is a common plant found growing in these soils. Many species of birds, fish, and invertebrates rely on these soils for critical habitat.

DISTRIBUTION AND EXTENT: Rockingham and Strafford Counties, New Hampshire. New England and Eastern New York Upland, Southern Part (MLRA 144A). Great Bay soils may also occur along the coast of Maine and northeast Massachusetts. The soils of this series are not extensive; their total extent is about 1,350 acres.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Amherst, Massachusetts.

SERIES ESTABLISHED: Rockingham County, New Hampshire, 2022.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
1. Ochric epipedon--the zone from 0 to 7 centimeters (Ase horizon).
2. Sulfidic materials--the zone from 7 to 54 centimeters (Cseg horizon)
3. Peraquic feature--positive soil water potential (permanently submerged) at the soil surface. (Under 1.6 meter of water at the time of coring).
4. Particle-size control section--the zone from 0 to 100 centimeters (Ase, Cse, 2Cg1, and part of 2Cg2 horizon).
5. Lithologic discontinuity--silty estuarine deposits overlying clayey glaciomarine deposits, starting at 54 centimeters (2Cg1 and 2Cg2 horizons).

ADDITIONAL DATA: Support pedons used to develop this series include--S2021NH015007, S2006NH017201 (sampled by KSSL, Lincoln, NE), and S2006NH017208 (sampled by KSSL, Lincoln, NE).

National Cooperative Soil Survey
U.S.A.