Connecticut’s Glacial History

• The Connecticut landscape today is in a quiet period.

• The mountains that formed about 550 to 245 million years ago have eroded down to gentle plains.

• The ocean rose and fell over time and washed away the eroded sediments.

Then Came the Ice Ages.

• The Earth’s climate began cooling around 35 million years ago, 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, from approximately 110,000 to 10,000 years ago .

• The most recent advance came through about 24,000 years ago, and that ice sheet spread rapidly as far as the southern edge of Long Island, and also far out into the present Gulf of Maine. 

Extent of Glaciation in

North America

Connecticut was covered with ice 20,000 years ago

Continental Glaciers are thick

• Maximum 6000-7000 feet thick.

• In New Haven - 1800 feet thick

• In Hartford - 2500 feet thick.

Great continental glaciers smothered Connecticut, bulldozing its soils away to the south

where they left a pile named Long Island.

What do Glaciers do to the Land?

When they melted, the glaciers dropped the sediments they were carrying from the north.

Melting glaciers left rocks behind

Glaciers Cave and Smooth Valleys

• New England hills are covered with an average of ten feet of glacial till.

• Glaciers have flattened the Connecticut Valley and made farming easier.

• Because sedimentary rock erodes easily, the Central Valley is almost totally free of boulders that the glaciers pushed south.

Glaciers Cave and Smooth Valleys

Valleys become U-shaped

Rocks carried and deposited by the glacier are called till

Glacial Till in the Woods

What is a moraine?

Hammonasset Moraine (pile of till created by a glacier)

• The result is a deposit called till, a mixture of everything from clay to house-sized boulders.

• Connecticut is full of rock chunks from Massachusetts, New York, Vermont, and Quebec.