Transcript Long Island Sound

The Geologic History of Long Island Sound
500 million years ago
Volcanoes form in a now extinct ocean.
450 million years ago
Volcanic islands crash into what will be North America
forming the bed rock of Long Island and L.I. Sound.
300 million years ago
Long Island Sound is a swamp
at the edge of newly formed mountains.
Pangea
135-65 million years ago
Sediments are deposited
by numerous rivers coming from the mts.
65-2 million years ago
Sediments are carved by a river forming a valley.
150,000-22,000 years ago
Series of glaciation and warming periods
between 2-5 glaciers cover the Sound.
22,000-20,000 years ago
Last glacier bulldozes the sediment from the river valley
making it deeper. Then it begins melting at its edge, dumping
sand, rocks and boulders on Long Island.
Glacier
20-16,000 years ago
Water from the melting glaciers forms a lake in what is now the sound.
15,000 years ago
Sea levels rise high enough to spill over into Sound in the east.
11,000 years ago
Sea Levels continue to rise
The ocean breaks through on the west forming Long Island.
Sea Rises
Long Island Sound today
Further Study