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Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate...

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Chapter 2 The Sea Floor
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Page 1: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Chapter 2

The Sea Floor

Page 2: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

The Water Planet

OCEANS

Cover 71% of the globe

Regulate earth’s climate and atmosphere

Page 3: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

The Geography of the Ocean Basins

Northern Hemisphere: 61% water

Southern Hemisphere: 80% water

Page 4: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Ocean Basins Four Ocean Basins

Pacific: Largest

AtlanticIndianArtic: Smallest

Page 5: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

The Structure of the Earth

Earth = 4.5 Formed from the

Big Bang:cosmic explosion of dust

Occurred 13.7 billion years ago

Dust Particles kept colliding until planets formed.

Page 6: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Early Earth

Early earth was most-likely MOLTEN.

As earth cooled: Densest material flowed toward center of

earth. Lighter materials floated toward the

surface.

Page 7: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Earth Began to Cool As Earth Cooled: Atmosphere formed

Oceans formed

Page 8: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Internal Structure of Earth

Core inner-most layer

Composed of iron

Page 9: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Internal Structure of Earth

Mantle• Molten-solid

rock• Flows around

core like liquid

Page 10: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Internal Structure of Earth

Crust• Outermost,

best-known layer

• Thin• Floats on Mantle

Page 11: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Two Types of Plates Make Up the Earth’s Crust

Continental Oceanic

Composition Granite Basalt

Density Less Dense More Dense

Age (oldest rocks) 3.8 Billion Years Old

200 Million Years Old

Elevation Above Sea Level Below Sea Level

Page 12: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

The Origin and Structure of Ocean Basins

THE EARTH IS IN A STATE OF CONSTANT TRANSFORMATION.

Page 13: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Early Evidence of Continental Drift Sir Thomas Bacon (1620): noticed

the coasts of continents fit together like puzzle pieces.

Alfred Wegener (1912): Proposed continental drift hypothesis.“All Continents were once joined”: PANGAEA

Page 14: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 15: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Pangea

Page 16: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

The Theory of Plate Tectonics

Wegener’s hypothesis was not widely accepted because he could not explain HOW continental drift occurred.

Page 17: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

The Theory of Plate Tectonics

1950s-1960s: Scientists had enough evidence to conclude that continents did “drift.”

PLATE TECTONICS

Page 18: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Discovery of the Mid-Ocean Ridge

Sonar lead to discovery during WW2

Continuous chain of volcanic mountains that encircle the globe

Page 19: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 20: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Significance of the Mid-Ocean Ridge

The Sea floor is created at the Mid-Ocean Ridge

Page 21: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Magnetism of Ocean Floor Rocks

BACKGROUND: Earth magnetic field reverses direction every few million years. Many rocks contain tiny magnetic particles & these move in molten rock. When the rock solidifies the particles freeze in their orientation

Geologists found patterns of magnetic bands or stripes in the sea floor running parallel to the mid-ocean ridge

The bands are symmetric around the ridge Magnetic bands = magnetic anomalies

Page 22: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 23: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

How is the Sea-floor Created???

1. Magma pushes through the mid-ocean ridge

2. Magma cools to form new sea floor

3. As more magma pushes through, the sea floor spreads out—

SEA-FLOOR SPREADING

Page 24: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 25: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Sea-Floor Spreading & Plate Tectonics

Earth’s surface is broken into plates.Plates are made of crust and top layer of mantle: LITHOSPHERE

Plates spread 2-18 cm per year. (Fingernails grow 6 cm per year.)

Page 26: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Plate Movement

As plates move, they collide with other plates.

*USUALLY* Subduction Occurs: one plate

is forced into the mantle when 2 plates collide.

Page 27: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 28: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Types of CollisionsOceanic-

OceanicTrenches (deep cracks in the crust) are formed.

Page 29: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Types of Collisions

Continental-OceanicTrenches produced.

Page 30: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Types of Collisions

Continental-Continental: produces mountains.

Page 31: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Sliding Plates

Sometimes plates slide past each other

Faults are formed from this process

Earthquakes are produced from this process

Page 32: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

What Makes Plates Move??? SLAB PULL:

oceanic crust becomes too heavy to float on the mantle and it sinks down into it, pulling the rest of the plate with it (slowly).

Page 33: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Geological History of the Earth

Continents were once united: PANGAEA

PANGAEA: began to break up 180 million years ago.

Page 34: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Geological Provinces of the Ocean

*M o st m arin e life*Best fi sh in g

*1km - 750 m lo n g

The Continental Shelf( Su bm erged part o f the co n t in en t)

*P art o f co n t in en t thatbegin s to slo pe do w n

*3,0 0 0 - 5,0 0 0 m lo n g

The Continental Slope( A ctu al edge o f the co n t in en t )

*P ieces o f the co n t in en talslo pe b reak o ff

an d co llect to fo rmthe r ise.

The Continental Rise( W here co n t in en tal

sed im en ts are depo sited )

Continental M argin s( Bo u n daries betw een co n t in en ts)

Page 35: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 36: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Types of Continental Margins

Active: Narrow shelves Steep Slopes Little or no rise

*Example: Pacific Coast of North America

Page 37: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Types of Continental Margins

Passive Wide shelves Gentle slopes Well-developed rise

*Example: Atlantic coast of North America

Page 38: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Deep Ocean Basins

Deep-sea floor (ABYSSAL PLAIN): average of 4,000 m deep (13,000 ft)

Page 39: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Features of the Deep-Sea Floor

Trenches :the deepest part of the ocean floor

Rift Zone: break in the earth’s crust from which lava flows and new seafloor forms.

Seamounts :submarine volcanoes Guyots: flat-topped volcanoes (INACTIVE) Abyssal Plain: flat part of seafloor Abyssal Hills : small hills Plateaus: flat-topped mountains

Page 40: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.
Page 41: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Guyots Flat-topped

seamounts

Page 42: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Trenches

Deepest parts of the ocean.

Deepest: 36,163 ft.

Page 43: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Mid-Ocean Ridge and Hydrothermal Vents

Central Rift Valley Located in center of

Mid-Oceanic Ridge where plates are pulling apart.

Page 44: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Hydrothermal Vents

Deep-sea hot springs

Formed when water that has been heated by the mantle forces its way through the earth’s crust

Page 45: Chapter 2 The Sea Floor. The Water Planet OCEANS Cover 71% of the globe Regulate earth’s climate and atmosphere.

Black Smokers

Chimney-like structures

Build up around vents

Release “clouds” of minerals that have been heated by the vents


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