Geological Processes

How people live and work is determined in part by geography. The push and pull of geologic processes, such as beach erosion and deposition, have helped shape settlement patterns throughout the Greenwich Bay watershed.

Greenwich Bay's coastline is made up of rocky shoreline and sandy beaches with four coves spread along the northern shore, and one cove on the southern shore. Much of the land that stretches away from the shoreline is a delta plain, including Potowomut Neck, which formed when water from a melting ice sheet deposited sediment into a glacial lake that is now occupied by Narragansett Bay. Hills and sharply elevated land in western and northern portions of the watershed are comprised of glacial till deposited beneath the ice sheet. In time, the glacial lake drained and lower sea levels exposed much of the bay bottom, allowing early peoples to forage the cold, forested land for food. As temperatures warmed, the ice sheet melted and receded north. Sea level rose dramatically, flooding the bay and drowning parts of the delta plain. A new environment of leafy forests and grassy fields resulted, enabling the Narragansett Indians to first farm in the area.

The bay's geology has provided the foundation for shipping, fishing, manufacturing, and recreation that has for centuries drawn people to the area. The bay continues to change with natural geological processes, however, and people have had to adapt to shifting geology. For example, in the late 1700s, East Greenwich used financial incentives to encourage people to build wharves to combat erosion.

Storm waves and elevated storm surges create erosion, which structurally harms homes and businesses, alters habitats, and washes away beaches. Efforts to address erosion at places such as Oakland Beach have met with limited success, leaving a wary bay community to watch the changing coastline and worry about the future of Greenwich Bay homes, businesses, and shorelines.

Sediment deposition has also created concerns in the bay area, especially among marine businesses and boaters who say nature's continual shoaling of the bay floor complicates boat travel in the shallow bay. Shoaling was not a problem in the late 1770s, when Warwick and East Greenwich coves were deep enough to host large cargo and passenger ships, when there was at least ten feet of water where there is dry land today. According to a history of the area, a large schooner "could tie up at (Greenwich Cove's) Jail Wharf and some were so big that their bowsprints reached in as far as…the old Shore Mill (on King Street)" (McPartland, 1960).

The above image is of Greenwich Bay Marina. The sand you see lining the shoreline was not there six years ago. The small stream you see cutting through the deposited sand is from a storm drainpipe that leads to Greenwich Bay from the inland streets and neighborhoods. The newly deposited sand is a direct result of municipal sand flowing through the storm drain and into the bay.

A similar situation is occurring just down the street at Norton's Marina The storm drain you see here has created the shallow waters that you see in the below image. This new sand bar stretches out nearly 20 feet into the Marina, rendering the area useless for boat slips. Marina owners argue that dredging could not only rectify this situation, but also promote cleaner water.

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