The Falls River watershed lies in a complex geological region whose earliest development is
not entirely understood. Mounting evidence suggests that the area was once part of a volcanic
micro-continent off the coast of Africa. Shifting landmasses associated with plate tectonics
eventually resulted in Essex along with the rest of the Connecticut coast forming part of the
North American coastline some 250 million years ago.
It is located on the southeastern flank of a very complex geologic structure called the
Killingworth dome. Starting near the center of the dome in the area where the Chester - Deep
River – Killingworth town lines meet, the Falls River watershed dips steeply from west to
east, dropping more than 300 vertical feet before entering the Connecticut River 13 miles
downstream in Essex. The watershed contains a tributary drainage area of 18 square miles,
approximately half of which are within the Town of Essex. The steep gradient of the river
made the later development of water power possible.
The Falls River enters the Connecticut River at North Cove, a 230 acre estuary. On the
northeast, it is bordered by Great Meadow, a tidal wetland of about 175 acres made up of
sediment deposited by over-bank flooding. Great Meadow is underlain by glacial meltwater
deposits that once choked the entire river valley and has been modified by the modern river
forming a series of pendant bars or levees in the Connecticut River, helping to separate North
Cove from the river.
The appearance and nature of both the Falls River and North Cove are best understood on a
geological timescale. The wetlands of the Connecticut River are the result of the last Ice Age
which covered the area with a sheet of ice 1-mile thick. As the glacier began to retreat some
20,000 years ago, melt water gathered behind the moraine remaining on the western shore
of Long Island, forming a large fresh water glacial lake . As the glacial ice eventually melted
back to the Arctic Circle, sea water levels on the Connecticut coast rose by more than 400 feet
and created what geologists call a “drowned coastline”. The natural dams that had separated
Long Island Sound from the Atlantic Ocean were also flooded and opened the Sound to the
Atlantic Ocean.
To this day, Long Island and its Sound act as a natural breakwater, greatly protecting the
Connecticut coast from pounding waves and from the effects of the worst winds. This so-
called low–energy coastline explains why the Connecticut River deposits so much of the silt it
carries at the mouth of the river rather than washing it out into the ocean.
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