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Structure of the Earth
1. The structure of the Earth consists of;
a) a thin crust
b) a mantle (solid, but can flow slowly)
c) a liquid outer core (made from nickel
and iron)
d) and a solid inner core (again, made
from nickel and iron).
Structure of the Earth
Seismic Waves
1. The structure of the Earth is known
because of the way shockwaves from
earthquakes (seismic waves) travel
through it.
2. These waves are detected using
seismographs.
Seismic Waves
P-Waves
S-Waves
Continental Drift
1. The theory of continental drift
suggests that they were the continents
were once joined together and have
since split and moved apart.
2. Continents (e.g. Africa and South
America) have shapes that fit closely
together and have similar patterns of
rocks and fossils
Continental Drift
Continental Drift
Tectonic Plates
1. The lithosphere (crust and upper
mantle) is cracked into a number of
large pieces (tectonic plates).
2. Convection currents caused by
radioactive decay is responsible for
these plates moving.
Constructive Plate Boundary
Plate boundaries
Tectonic plates can
• slide past each other (conservative
plate boundary)
• move towards each other (destructive
plate boundary)
• move away from each other
(constructive plate boundary)
Constructive Plate Boundary
Constructive Plate Boundary
Destructive Plate Boundary
Destructive Plate Boundary
Conservative Plate Boundary
Mountain formation