Peat Resources and Glacial Geology of Chapman Swamp and Adjacent Area Westerly, Rhode Island

Author

William David Hughes, University of Rhode Island

Date of Award

1982

Degree Type

Thesis

Degree Name

Master of Science in Geology

Department

Geology

First Advisor

Jon C. Boothroyd

Abstract

Chapman Swamp is a 685 ha freshwater wetland complex in Westerly, Rhode Island. Seventy percent of the wetland area is forested. 17.9% is scrub-shrub, 7.0% is aquatic bed and 1.3% is emergent.

The peat stratigraphy in the wetland is composed of wood, reed-sedge and moss peats. Wood peat is typically low ash, reed-sedge peat is variable in ash content depending on proximity to a fluvial sediment source and moss peat is high-ash in basal sections due to contamination from eolian sources in the early Holocene. The most common stratigraphic relationship is wood peat overlying moss or reed-sedge peat. The maximum and average peat thicknesses in the wetland are 325 cm and 160 cm, respectively. The wetland basin contains 10,731,000 cubic meters of peat, 6,053,000 cubic meters (1,203,180 tonnes, air dry) of which is fuel-grade. Fuel-grade wood peat has the highest mean calorific value (6401 BTU/lb, air dry), reed-sedge is second (6024 BTU/lb, air dry) and moss is lowest (5691 BTU/lb, air dry).

The area of the resource with the highest energy potential could supply the fuel to produce more than 20% of the town of Westerly’s electricity for 45 years or hear 1000 homes heated by wood stoves for 50 years.

The Chapman Swamp basin is a remnant of a shallow ice-marginal lake that existed during late Woodforian deglaciation of Rhode Island. Primary sedimentary structures observed in deposits around the margin of the basin and from a vibracore near the margin are characteristic of delta-plain, delt-front, pro-delta slope and lake-bottom depositional environments of a kame-delta depositional system. Initially lake drainage was to the southwest along the north side of the Charlestown Moraine. Ice retreat allowed drainage to the north through the Pawcatuck River valley, lowering lake level to expose divides which separated the lake into several small basins. Hydrophytes became established and peat accumulation began.

The association of this wetland with a former glacial lake basin in one part of a continuum of relationships between peat and glacial environments in southern New England.

Recommended Citation

Hughes, William David, "Peat Resources and Glacial Geology of Chapman Swamp and Adjacent Area Westerly, Rhode Island" (1982). Open Access Master's Theses. Paper 2055.
https://digitalcommons.uri.edu/theses/2055