The Seafloor

The oceans are classified into four major basins The oceans are classified into four major basins Pacific Pacific Atlantic Atlantic Indian Indian Arctic Arctic

Oceans of the World

The Origin and Structure of the Ocean Basins

Structure of Earth Core-innermost layer, iron-rich, high pressure, 4000 degrees Celsius Core-innermost layer, iron-rich, high pressure, 4000 degrees Celsius Mantle-outside core, very hot, semi-plastic, flows and swirls around slowly like thick liquid Mantle-outside core, very hot, semi-plastic, flows and swirls around slowly like thick liquid Crust-outermost layer, very thin, like rigid skin atop mantle Crust-outermost layer, very thin, like rigid skin atop mantle -Oceanic-sea floor, composed of basalt mineral (darker color and denser) (darker color and denser) -Continental-composed of granite (light color), thick blocks of crust floating on mantle

Continental Drift

Alfred Wegener Suggested supercontinent Suggested supercontinent Pangaea Pangaea By 1960s Scientists concluded the continents did drift By 1960s Scientists concluded the continents did drift Plate Tectonics Plate Tectonics

Mid–Ocean Ridge SoNAR allowed the formation of detailed surveys of the ocean floor SoNAR allowed the formation of detailed surveys of the ocean floor The mid ocean ridge system was discovered The mid ocean ridge system was discovered Sound travels through air at about 337 meters pr second. Sound travels through air at about 337 meters pr second. Through water at 1460 meters per second! Explain…… Through water at 1460 meters per second! Explain……

Cross Section of Mid Ocean- ridge

Sea-Floor Spreading Subduction-The downward movement of a plate Subduction-The downward movement of a plate

GEOLOGICAL STRUCTURE OF THE OCEAN

Continental shelf Gently sloping, shallow Gently sloping, shallow

Continental slope Steeper, extends seaward from shelf Steeper, extends seaward from shelf

Abyssal plain Relatively flat, contains seamounts and trenches Relatively flat, contains seamounts and trenches

Mid-Ocean Ridge and Hydrothermal Vents Up to 660 F Up to 660 F Releases sulfides Releases sulfides

HISTORY OF L.I.S.

Dimensions 110 miles long 110 miles long 21 miles at the widest pt. 21 miles at the widest pt. 248 miles of beach (only 95 public) 248 miles of beach (only 95 public) Avr. Depth 65 feet Avr. Depth 65 feet 44 sewer treatment plants!!!! 44 sewer treatment plants!!!! F temp F temp.

200 MYA.-North America and Africa drift away from each other. 200 MYA.-North America and Africa drift away from each other.

3 Mya. Glaciers covered the land from Canada to Connecticut. 3 Mya. Glaciers covered the land from Canada to Connecticut. Sea level dropped. Why? Sea level dropped. Why?

22,000 years ago The glaciers reached the southernmost point (the middle of Long Island) 22,000 years ago The glaciers reached the southernmost point (the middle of Long Island) The ocean was 350 feet lower than it is today. The ocean was 350 feet lower than it is today. The coastline was 150 miles south of Long Island. The coastline was 150 miles south of Long Island.

Glacier plucking

The ice began to melt leaving deposits of sand and rocks in moraines. The ice began to melt leaving deposits of sand and rocks in moraines. This formed a freshwater lake from the melting ice. This formed a freshwater lake from the melting ice. The lake accumulated to a depth of 500 feet (350 feet current max. depth :the race) The lake accumulated to a depth of 500 feet (350 feet current max. depth :the race)

The freshwater broke through forming the race The freshwater broke through forming the race 8,000 years ago seawater began to flow back into the lake. 8,000 years ago seawater began to flow back into the lake. As the water level went up a second opening occurred near NYC. called Hells Gate As the water level went up a second opening occurred near NYC. called Hells Gate Now known as an estuary Now known as an estuary

Estuary A partly enclosed coastal body of water where seawater and freshwater meet and mix. A partly enclosed coastal body of water where seawater and freshwater meet and mix.

Soon after the glaciers began to melt the first humans reached the coast. WHY? Soon after the glaciers began to melt the first humans reached the coast. WHY? In the 1600s Ct. had one of the densest pop. of Native Americans in the U.S. In the 1600s Ct. had one of the densest pop. of Native Americans in the U.S.

1614- Adriaen Block- Dutch explorer sailed through Hells Gate, out at the Race and on to Block Island Adriaen Block- Dutch explorer sailed through Hells Gate, out at the Race and on to Block Island. He then went up the Connecticut river to what is now Hartford. He then went up the Connecticut river to what is now Hartford.

Settlers 1630s- English and Dutch settlers purchased land from Native Americans. 1630s- English and Dutch settlers purchased land from Native Americans.

Maritime development 1700s- Trade routes between Ct. and West Indies. 1700s- Trade routes between Ct. and West Indies. Sugar, Molasses for cattle, pig. Sugar, Molasses for cattle, pig.

WAR The British occupied Long Island but not CT. The British occupied Long Island but not CT. CT…Home of the Privateers. CT…Home of the Privateers.

Ship building Ship building Whaling Whaling Oystering Oystering Fishing……What happen to the Samon etc.? Fishing……What happen to the Samon etc.?

Transportation The New Haven RR The New Haven RR I95 I95 Rec. Boats Rec. Boats

Industry Once farming, now cities…. Once farming, now cities…. Factories for guns, clothes, clocks and locks… Factories for guns, clothes, clocks and locks…

ESSAY Explain how Long Island Sound was created. Explain how Long Island Sound was created. Include : effects of Glaciers, Plate tectonics,salt vs freshwater, human impact and time. Include : effects of Glaciers, Plate tectonics,salt vs freshwater, human impact and time.