The Earth’s climate began cooling around 35 million years ago (Cenozoic Era), but glaciation in the northern hemisphere began only 3-5 million years ago. During this time, Connecticut has been covered by ice at least two times, maybe more. (Bell, 1985)
The last of the glacial advances (the Wisconsinan) at its thickest:was 6000-7000 feet thick. (Bell, 1985) In New Haven it was 1800 feet thick and in Hartford it was 2500 feet thick. (Patton, Kent, 1 992 )
About 14,000 years ago a lake formed called Glacial Lake Hitchcock. It began at a natural dam in Rocky Hill and extended 150 miles northward. At its widest point it was 20 miles across. (Patton, Kent, 199 2)
Glaciation or rather deglaciation was an important factor in shaping and creating Connecticut’s coastline. The ice cap that covered one half of North America captured alot of water. As a consequence, sea level dropped more than 250 feet, thus turning continental shelf into dry land. Rivers stretched across this new land, cutting deep valleys into the shelf. When deglaciation began about 18,000 years ago,melting icewater headed back into the ocean. (Bell, 1985)
Today sea level is back up to about the same height as in preglacial times, but has also flooded the lower areas of many valleys. This gives Connecticut a “drowned coastline.” (Bell,1985)
Glaciation is also partly responsible for the modern day version of LOng Island Sound (it used to be a freshwater lake). Within it is part of a terminal moraine, which is a mark of the maximum advance of a glacier. Along the same line, recessional moraines are responsible for the creation of many islands off our coast. These mark a brief standstill in glacial retreat. (Bell, 1985)
In 1825, Peter Dobson of Vernon,Connecticut became puzzled by round boulders randomly mixed in with sand and clay, that his workmen kept digging up. He proposed that the only thing that could account for this was being carried by ice. Since he wasn’t a scientist, his ideas were given little notice.(Bell, 1985)
New England hills are covered with an average of ten feet of glacial till. Examples of this till can be seen in the many stone walls found in our state. (Little, 1990) Glacial drift covers most likely 99 percent of Connecticut’s bedrock. Glaciers have flattened the Connecticut Valley and made farming easier. Because brownstone, a sedimentary rock erodes easily, the Central Valley is almost totally free of boulders that the glaciers have famously dumped elsewhere. (Bell, 1985)
In addition, brownstone was easily dug into by glaciers and carved out many lakes. Lake Saltonstall in Branford, is an example of this.Evidence of glaciation can also be seen in the gouged out rocks the glaciers used to cover-ex. at East Rock. (Bell, 1985)
Connecticut is still recovering from the last ice age. Glacial ponds are filling into swamps. Swamps are filling into wet forests. Erratic boulders are tumbling down from ridges. Rivers and streams still carry glacial sediments to the ocean and sea level is still rising. (Bell, 1985)
The Wisconsin Glacier advanced north to south, so it built drumlins and scoured hills of bedrock along a north-south route. Without glacial deposition our coastal recreational areas would be nonexistent. (Patton, Kent, 1992)
In many places, the varves of silt and clay laid down by the Central Valley’s glacial lakes has been used to make bricks. (Bell, 1985)
Right now we are in an interglacial period, but scientists expected another ice age to return in 500-7000 years. (Bell, 1985)
