Transcript Earth`s Interior and Plate Tectonics

Plate tectonics
Layers of the earth
 From
outside to
inside: crust,
mantle, outer core,
inner core
 Lithosphere = upper
mantle & crust
 The lithosphere acts
as one layer
Plate tectonics
 Lithosphere
is divided into several
major plates
 The plates can move and change
shape and size
 The plates are not exactly the
same as continents.
 Interaction of the plates is what we
call plate tectonics
Plate tectonics
 Plates
move about 5 cm a year
(the length your fingernail grows)
 Plates move because of
convection currents in the mantle.
 Hot material moves up and cool
material moves down
Effects of the Movement
Do you think moving 5 cm makes any
difference in the Earth?
 This small movement builds up great
pressure.

Seafloor spreading
Seafloor = floor at the bottom of the
ocean
 Seafloor spreading = rising magma
forces the crust upward and apart,
making new seafloor
 All of the seafloor was made in the last
200 million years

Seafloor spreading
Effects of plate movement
 Tectonic
plates moving causes:
 Earthquakes
 Volcanoes
 Mountain Building
 What
causes Earthquakes?
Evidence for plate tectonics
 Earthquake
patterns:
 Earthquakes occur most often
on plate boundaries
Evidence for plate tectonics

Paleomagnetism:
 Scientists can see
magnetic patterns
in the seafloor
 This allows us to
see how new
seafloor has formed
over time
How can we find out the
age of rocks at the
bottom of the ocean?
Evidence for plate tectonics

Ocean Drilling:
 Scientists can
measure the age of
the seafloor
 This lets us see that
new seafloor has
formed from
seafloor spreading
recently