Transcript Evidence of Seafloor Spreading

Evidence of Seafloor
Spreading
By: April Carlisle and Stephen Loucks
Harry Hess
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The surface of this planet is not fixed as it seems but rather broken up
like pieces of a jigsaw puzzle. There are enormous plates that move
under Earth, this process is called plate tectonic, and it transformed
the thinking of geologist everywhere. One of them, Harry Hess, was a
factor in figuring out how plate tectonics worked.
In 1960, Harry Hess studied Wegner's theory.
In 1962, as a result of oceanographic research conducted in the 1950’s
Harry Hess proposed the theory of seafloor spreading to account for
continental movement. He suggested that continents do not move
across oceanic crust, but rather that the continents and oceanic crust
move together. Hem suggested that the seafloor separates at oceanic
ridges and that new crust is formed by upwelling magma.
Alfred Wegner
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In 1912, he purposed the idea of continental drift , which he believed
was true because of the different placement of animals, plants,
fossils, and glacial deposit. Wegner's idea was not accepted by the
scientific community at this time because there was little evidence to
support his theory. In the late 1960’s there was a growing amount of
evidence to support his idea, which is now widely excepted.
Evidence of Seafloor spreading
Showing rifting
 Seafloor spreading and other tectonic activity processes are the result
of mantle convection. Mantle convection is the slow, churning motion
of Earth’s mantle. Convection currents carry heat from the lower
mantle and core to the lithosphere. Convection currents also
“recycle” lithospheric materials back to the mantle.
A rift valley is a large elongated depression with steep walls formed
by the downward displacement of a block of the earth's surface
between nearly parallel faults or fault systems.
Sonar is a technique that uses sound propagation to
navigate, communicate with or detect objects on or
under the surface of the water, such as other vessels.
Sonar uses sound waves to see
in the water when were up on
land or in a boat. It is used
to navigate the seafloor, it plays a
big role in helping us understand
how are seafloor is changing.
Instruments used to see the seafloor
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Magnetometer, an instrument used to measure the magnetic
properties of the ocean floor.
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Satellites that detect and observe different characteristics and
features of the Earth's atmosphere, lands, and ocean are often
referred to as environmental satellites. Most environmental satellites
have one of two types of orbits: geosynchronous or sun-synchronous.
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SOund NAvigation and Ranging—SONAR—is used to find and identify
objects in water. It is also used to determine water depth . Sonar is
applied to water-based activities because sound waves attenuate less
in water as they travel than do radar and light waves.
Keeping earth in shape !!!!!!
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Seafloor spreading is just one part of plate tectonics. Subduction is
another. Subduction happens where tectonic plates crash into each
other instead of spreading apart. At subduction zones, the edge of the
denser plate subducts, or slides beneath the less-dense one so, the
denser lithospheric material then melts back into the Earth's mantle.
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Seafloor spreading creates new crust and subduction destroys old
crust. The two forces roughly balance each other out, so the shape
and diameter of the Earth remain constant.