Transcript The Seafloor Lesson 4

The Seafloor
•UNIT 8
•STANDARDS: NCES 2.1.1, 2.1.4,
2.3.1, 2.6.4
•LESSON 4
Lesson Objectives
• In this lesson, you will learn about:
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The reason for continents and ocean basins
The major features of continental margins
The major features of ocean basins
The different types of marine sediment and
their origins
Oceanic and Continental Crust
• General Ocean
• High mountains and deep
topography
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• Continental
Margins
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depressions (trenches)
The deepest point is the
Marianas Trench in the Pacific
Ocean
Continental and Oceanic are
the two types of the crust
The submerged parts of the
continents.
Shallowest part of oceans
Continental Shelf
• The continental margins are the areas where the edge of
the continents meet the ocean.
• The shallowest part is the continental shelf and extends
to slope down to the continental rise and eventually the
ocean floor.
• The continental shelves are of great economic
importance. First of all, about 90% of the world’s
supply of seafood comes from here. Second, valuable oil
deposits can be found in some shelf areas.
Continental Slopes
• Continental
Slope
• Turbidity
Current
• Continental
Rise
• Beyond the continental shelf, the
seafloor drops off quickly. These
regions are continental slopes.
• Cut the underwater canyons. They are
rapidly flowing water on the seafloor
carrying heavy loads of sediments.
• The deposited sediments by the
turbidity currents and rest on the
seafloor. They will build the
continental rise.
Ocean Basins
• Abyssal Plains: Smooth parts of the ocean
• Ocean Basin
Features
floor covered in hundreds of meters of mud.
• Deep-Sea Trenches: cut by turbidity currents
and are the deepest parts of the ocean. Often
lie near subduction zones. Marianas Trench,
deepest part on the globe.
• Mid-Ocean Ridges: Underwater mountains
formed by new oceanic crust .
• Hydrothermal Vents: Holes on the seafloor
where fluids heated by the hot magma erupts.
Black smokers are the most common.
Marine Sediments
• Source
• Sediments cover the ocean floor.
Smoothest, flattest part of the earth is
the abyssal plain where sediment is
hundreds of meters thick and
undisturbed.
• Sediments originate on the continents
and are washed into the oceans.
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Deep Sea OOZE
• Formation
• Formed by the shells and body
parts of marine organisms.
When the organism dies, its
remains rain down onto the
ocean floor. VERY slow to
dissolve.
• Generally accumulate at a rate
of millimeters per thousands
of years.
Manganese Nodules
• What are they?
• Nodules (packets similar in size
to a potato) that contain
manganese, iron, copper, and
other valuable metals.
• How do they
form?
• The metals are precipitated
directly from the seawater and
collect in these nodules.
EXTREMELY SLOW growth,
millimeters per millions of years.
Marianas Trench
• The deepest part of the ocean.
• The deepest point below sea level on the
planet.
• Watch the video of the exploration of the
trench. History Channel: Marianas Trench
NatGeo Video Clips
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Drain the Ocean (Part 1 of 5) Drain the Water
Drain the Ocean (Part 2 of 5) Organisms
Drain the Ocean (Part 3 of 5) Plate Movement
Drain the Ocean (Part 4 of 5) Tallest Mountains
Drain the Ocean (Part 5 of 5) Massive Structures
Ocean Landscape Summary
Section Review 8.4.1
• How are submarine canyons formed?
• Which sediments do you think sink faster,
pebbles or sand grains?
• Arrange the following sediments from
CLOSEST to land to DEPEST Ocean:
Pebbles, silt, sand, clays, animal shells.
• Why are companies investigating harvesting
manganese nodules?