By Matt Kirwan – USGS

The work of settlers clearing the land two centuries ago may have had a far greater impact on wetland growth than previously known, according to a new U.S. Geological Survey study. Researchers found that deforestation in the New England area at that time produced significant soil erosion, increasing sediment delivery rates -- the natural flow of sand and soil in water systems. The large amounts of sediment traveling in rivers and streams to the coastline spurred a significant period of wetland growth, leading to marshes lining the coast of New England that today are abnormally large.

“For more than 40 years, the rise and fall of sea-level has been thought to control the formation and behavior of coastal marshes,” said Matthew Kirwan, USGS research geologist and lead author of the new report. “Our findings suggest however that sediment delivery rates related to historical land use change are equally, and in some cases, a more important factor.” The scientists collected core samples along the Plum Island Estuary — the largest in New England— correlating the presence of fossils and other organic matter to the initial formation of the salt marsh. They found that these marshes began expanding rapidly during the 1700s and 1800s, a time when settlers were clearing forests and replacing them with farms. For full press release, click here.