Transcript Lab 4-3: Sea-Floor Spreading

Lab 4-3: Sea-Floor Spreading
Pages 155 – 158
Vocab
• Sea-Floor Spreading:
– Ocean crust is created at a divergent boundary as
plates pull apart and molten material rises from deep
within the Earth.
• Mid-Ocean Ridge:
– Boundary between
two plates where
new crust is created.
• Rift Valley:
– Valley between diverging plates.
• Seamount:
– Underwater mountain
• Continental Shelf:
– An undersea extension of a continent which
can stretch for many miles out to sea.
What prominent sea floor feature Is
found in the central Atlantic
Ocean?
• The Mid-Atlantic Ridge
What feature is found at a distance
of 4,100 kilometers on the ocean
bottom profile you constructed?
• An island (it’s above 0!)
What motion of the sea floor is
responsible for the formation of the
Mid-Atlantic Ridge’s rift valley?
• The ocean crust is moving in opposite
directions (diverging).
As distance from the Mid-Atlantic
Ridge increases, what change in
the age of the sea floor is
observed?
• Rocks get older as you move away from
the ridge.
How old are the oldest rocks of
the Atlantic sea floor?
• Jurassic / 142 – 206 million years old
Skip #6
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Describe the features of the North
Atlantic Ocean bottom that are
forming due to sea floor spreading.
• The Mid-Atlantic Ridge with a rift valley.