Download Plate Tectonics part 1

Earth Composition, Continental
Drift and Plate Tectonics
Structure of the Earth
Inner Core – The
center of the Earth.
Made of solid iron
and nickel.
Outer Core – Liquid
iron, gives earth its
magnetic field.
Structure of the Earth cont’d
Mantle – The largest portion
of the Earth, made of
dense rock.
x
Asthenosphere – The upper
most region of the mantle.
Rock in this layer is semimelted and can flow. This
is called plasticity. The
crust “floats” on this layer.
Structure of the Earth cont’d
Lithosphere – The solid outer region of the
Earth. The lithosphere is comprised of the
crust and a solid region of the upper mantle.
Structure of the Earth cont’d
Crust – The “outer skin” of the earth. Two kinds of crust:
Oceanic Crust – Only 3-6 miles thick, its dense rocks
make up the entire ocean basins.
Continental Crust – 20-50 miles thick, it is made of
less dense rock.
Pieces - The crust is made up of 12 major interlocking
plates.
How do we know what the Earth’s
interior is like?
Earthquake
waves
change
speed or
direction,
or are
absorbed
by different
layers.
Plate
Tectonics –
The study of
the formation
and
movement of
Earth’s
crustal
plates.
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Evidence for plate tectonics:
The continents look like they
“fit together” like pieces of
a puzzle.
Once good maps were made in
the1700’s, it was noted that
Africa and South America
looked like they fit together.
More evidence for plate tectonics:
Fossil Evidence:
Fossils of the
same type and
age found on
different, once
connected
continents.
More evidence for plate tectonics:
Matching Rock
Types: Rocks
of the same
type and age
on different
continents.
More evidence for plate tectonics:
V
Earthquake / Volcano
Locations:
The positions of
earthquakes and
volcanoes mark the
plate boundaries.
E
More evidence for plate tectonics:
Mid-Ocean Ridges:
Paleomagnetism – Rocks on opposite sides of midocean ridges have similar age and magnetic
polarity.
What drives plate tectonics?
• Convection currents (heat transfer) from Earth’s
core which is heated by radioactive decay causes
the mantle to circulate, which moves the crust.