Lisa S. Alter
When the first settlers arrived, it is estimated that the Native American population in Connecticut was around 20,000. By the mid 1600’s, four out of five of the established settlements were coastal communities. Today, almost half of the U.S. population lives in coastal communities (which make up 11% of our countries land). (Atkin, Bangser, Jacobson, Smith, Wade, Backer, 1991) The stresses that this population increase has had on the Sound will be discussed in the section on pollution.
During the past 1.8 million years, Connecticut’s coastline has moved tens of miles landward when sea level rose, and tens of miles seaward when sea level fell. These changes in sea level are caused by periodic, cyclic global cooling and warming. (Patton, Kent, 1992) In addition, changes in sea level are in response to plate tectonics. Influencing the Atlantic Ocean is the activity of the Mid-Atlantic Ridge. This results in progressive deepening of the ocean, away from the ridge. (Turekian,1996)
22,000 years ago, the last glacier that affected CT. reached its southernmost point. Sea level was 350 feet lower. The coastline lay 75-115 miles off the south shore of Long Island, on what is today the continental shelf (150 miles south of its present position). The thickness of the ice sheet was approximately 1800 feet at New Haven and 2500 feet in Hartford. (Patton, Kent, 1992)
The following is a summary of a time line from,
A
Moveable Shore
by Peter C. Patton and James M. Kent, 1992.
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17,000-18,000 years ago: As the ice retreated to expose the present Connecticut coastline, rivers from the melting glacier formed a freshwater Lake Long Island Sound. Sea level was 260 feet below its present position. At this time, cave paintings were done in Valencia, Spain. These are believed to have indicated global warming.
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11,000 years ago—Lake Long Island Sound overflows and a deep gorge is cut to meet the ocean. The oldest, undisbuted evidence of human occupation in North America is from this time period.
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10,600—First occupation of humans in Connecticut, is thought to be around this time, due to evidence found in other New England states.
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8000 years ago—Rising sea level (60 feet lower than today) starts the formation of present day Long Island Sound. Around this time, mammoth and mastodon become extinct. There is evidence of the climate rapidly warming and drying. Agriculture begins in Mexico.
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4500 years ago—Sea level is 33 feet lower than it is today. Connecticut’s climate is similar to the present one.
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1000 years ago—Sea level is 3 feet lower then it is today. The first salt marshes appeared in the Connecticut River estuary. The Woodland Indian culture in Connecticut was hunting and gathering.
Today, sea level is rising at a rate of 2-3 mm(one-eighth inch) per year. This is equal to the thickness of 2 1/2 credit cards. This sea level rise of 2mm. per year is equal to 200mm.(8 inches) in one hundred years, or about 2.5 inches since Connecticut was settled. (Patton, Kent, 1992)
Many scientists believe that the current rise in sea level is due to global warming (human-caused) canceling out the effects of plate tectonics. (Turekian, 1996)
Scientists term Connecticut’s coast, “a drowned coastline.” This is because the sea has encroached over the land, flooding the coastal plain. (Patton, Kent, 1992)
Storms also help to shape our coastline. The 1938 hurricane had the greatest storm surge ever recorded in Connecticut. Sea level rose 10 feet during this storm. Storm surges are caused by the following:
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Low barometric pressure of the storm, pulling the surface of the Sound upward.
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Counterclockwise winds that push ocean water into the Sound.
How close was the storm’s arrival to a spring high tide (a high tide that is higher than normal).
During the 1938 hurricane, erosion pushed the shoreline back 100 feet in places. (Patton, Kent, 1992)
More information on hurricanes and storm surges can be found in my Institute unit on “Severe Storms and Weather Forecasting,” from 1994.
In addition, due to prior rainfall and the speed with which the rain fell during the 1938 hurricane, two days later Connecticut had its second worst flood in 350 years. (Patton, Kent, 1992)
Nor’easters are storms that form off of, and move up the coast. These storms can cause up to 36 hours of wind and rain. They also help to erode our coast. (Patton, Kent, 1992)
Winds, waves, and currents also help to shape the shoreline. Tides bring and carry away sand and sediment. The difference between high and low tide varies along the coast. In Greenwich, the difference is seven feet, four inches. In New Haven, the difference is six feet, two inches. In Stonington, the difference is only two feet, seven inches. I cover wind, waves, currents and tides in global ocean and plan to review them in this unit, with a Long Island Sound twist. The book, “A Moveable Shore,” by Patton and Kent 1992, contains the above tide information. It also contains information about winds, waves and currents in Long Island Sound.
A sandy coast (beach) tremendously increases property value. When they erode due to natural forces and processes previously stated, property values drop. Thus, we attempt to stop the sand from eroding. In doing this, we are not always successful. Sometimes we make it worse and other times we only create temporary solutions. One example of this is the beach in West Haven. Their coastline has been pushed back up to 100 feet in 22 years. One million dollars has been put into projects to stabilize their shoreline. Much of this money has been wasted and some of the stabilization attempts have caused further erosion. (Patton, Kent, 1992)
Salt marshes are also important features of Connecticut’s coast. They produce more plant matter per acre than any other ecosystem. This makes them fertilizers for Long Island Sound and the rivers of Connecticut. They preform similar functions to the estuaries. Salt marshes are safe breeding and nursery grounds. They help to filter out pollutants. Marshes also act as buffers that reduce flooding and erosion. Since the time of the settlers, marshes have been drained, mowed for hay (I know a garden center that still sells salt marsh hay), ditched to prevent mosquito breeding. (Patton, Kent, 1992)
In Connecticut, we have lost 25-35 percent of the original marshes. Throughout New England, more than half have been destroyed. The destruction of marshes has slowed down due to regulations. Yet, almost 15,000 acres (about 23 square miles) of marsh has been destroyed in the last 40 years. (Patton, Kent, 1992)
Connecticut is known for its rocky coast, of which there are three types. Bedrock, bouldery and gravelly. Bedrock coastlines resist erosion, but get hit hard by storms. Bouldery resist erosion and all but the strongest storms. Gravelly coastline resistance falls in the middle of the other two. (Patton, Kent, 1992). An interesting activity is to go to the beach and separate out the sediment by size and percentage.