tectonics is a theory that scientists have made to explain how the
continental plates move. In 1912 a German scientist, Alfred Wegener,
first talked about continental drift and seafloor spreading. According
to the plate tectonics theory the surface fo the earth is made up
of 12 giant seventy-mile thick rock plates. The 12 plates fit together
a little bit like a puzzle does. They are constantly moving and
grinding against each other. Continental plates float on the aesthenosphere,
a liquidy plastic-like layer below the lithosphere, and it is also
called the mantle of the earth. The plates never stop moving. They
crunch against each other where they meet. Volcanoes and mountain
ranges are also found where the continental plates meet.
the lithosphere covers the entire surface of the earth, all of the
Earth's plates are part of the theory of continental drift. There
are some plates above the surface of the ocean and others that are
below the surface of the ocean. Under the surface of the ocean there
are mountain ranges called the mid-ocean ridge. The tallest mountains
in the world are found at the bottom of the Pacific Ocean.
years ago the continents were not in the same place that they are
today. They are now far apart. Because of what is called continental
drift, where the continents move, they have moved apart to where
they are today.
part of the continental drift theory tells us how volcanic activity
causes the seafloor to expand and swallow up parts of the earth
that are around it. The earth is recycled down into the hot
core and some of it comes back up through the vents in volcanoes
after it has melted.
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