Divisions of the Global
Ocean
 The __________ ocean is the _______ Ocean.
 The other oceans, listed from largest to smallest, are:
 ______________ Ocean
 ______________ Ocean
 _______________ Ocean
 _______________ Ocean
How Did Oceans Form?
 About ______ billion years ago, there were no oceans.
 Sometime before 4 billion years ago, water vapor in the ____________ condensed and fell as ____________.
 The rain filled the deeper levels of Earth’s surface and the first
___________ began to form.
HMS Challenger
• First dedicated exploration of the
_____________ (1872).
• Used a weighted line to find the depth of the water as they sailed.
• Slow and inaccurate, but it gave scientists an idea of the ocean floor.
•
Exploring the Ocean Floor
• Until recently, the ocean floor was ________________.
• The ___________, ________, and extreme ______________ required new technology.
• Most scientists prior to the
1900’s thought the ocean floor was flat, covered with layers of sediments washed in from the land.
•

Theory of Plate Tectonics
 Totally revolutionized our understanding of the Earth, past and present.
 Theory ranks with the theories on evolution, relativity, the
Big Bang, and Newton’s Laws.
Sonar
 Sound Navigation and
Ranging.
 Invented in WWI to hunt submarines.
 ____________ is bounced off the ocean floor to find the depth.
 The _________ the bottom is, the ______ the echo returns.
Reveling the Ocean Floor
 Regions of the Ocean Floor:
The two regions of the ocean floor are the _____________
___________ and the _______-
___________ ____________.
 Underwater Real Estate:
The continental margin and the deep-ocean basin are subdivided into different areas and have different features.
Studying the Ocean Floor
 Seeing by Sonar:
Scientists use sonar to determine the ocean’s __________.
 Oceanography via
Satellite:
 Scientists use images from the satellite
Seasat to study ocean currents.
 Studying the Ocean with Geosat:
Scientists use the
Geosat satellite to measure slight changes in the height of the ocean’s surface.

Submersibles
 Specially designed
______________ used by scientists to explore more than 1-km below the surface.
 Thick metal hulls protect the scientists from being crushed by the immense _________.
Continental Shelf
 _______ _________, shallow part of ocean floor that extends outward from the continent.
 Varies from a few kilometers to over 1300-km from shore.
 Provides nutrient rich home to large numbers of fish.
Continental Slope
 _________ slanting portion after the shelf.
 Bottom marks the edge of the continental _______.
Continental Rise
 ________ ______ at base of continental slope formed by accumulation of sediments that wash down.
Turbidity Current
Abyssal Plain


___________ parts of the deep
_________ ___________.
Covered with fine grained muddy ______________ (silt).
 Cover ___________ areas of the ocean floor.

 Rapid moving currents that carry large amounts of sediments.
 Similar to ______________ on land.
 Often cut canyons in the continental slope.

Mid-ocean ridge
 ____________ boundary underwater, where new crust is being formed from __________ deep in the ___________.
 Form underwater ____________ ranges that seldom break the _____________.
 Can be 1000’s of km wide, and over 80,000-km long.
 Passes through all the Earth’s ___________.
Seamounts
 Underwater ___________.
 If they reach the surface they form islands.
Volcanic Island Arcs
 These once underwater
_____________ grow so large they break the surface of the ocean.
 Associated with O-O convergent boundaries.

Deep Sea Trenches
 ______________ part of the ocean.
 Many ______________ deeper than the surrounding __________
____________.
 Very long (1000’s of km), but fairly narrow
(100-km across).
 Place where old crust is being subducted back into the mantle.
 Sign of ______________ boundary.