1. History & Formation of Long
Island Sound

2. History
• 18,000 years ago CT, LI were covered by ice
1000 m thick – Late Wisconsin Glacier
• Glaciation brought sea level change – 100 m
lower than today
• As glacier moved south it deposited sediment
called drift all around New England

3. Moraines
Where glaciers didn’t make headway;
melting rate= southward movement rate;
drift is deposited. Two locations this happens:
A) Ronkonkoma Moraine: Southernmost deposit
B) Harbor Hill Moraine: Northernmost deposit

7. Long Island Sound
• Basins carved by streams; lots of sand/gravel
deposited as glaciers retreated
• Deposits called outwash end up trailing south
LI
• Bounded by sills – which ones?
• Sills kept ocean water out for 8,000 years
• Around 25 m below present water begins to

10. Glacial Erratics –
Giant Boulders-
Glacial leftovers we
find on LI today
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