Transcript Slide 1

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.