The Earth’s Interior
Write down the things that are
in yellow
Other terms in this PowerPoint
are helpful but do not need to
be included in your notes.
I. Plate tectonics- describes
movement of the crust (theory)
A. Continental Drift- the continents have
drifted from one location to another
B. Continents used to be in one mass called
Pangea (250 mill. Years ago)
II. Earthquakes
A. Seismic Waves –
generated waves traveling through the
Earth’s interior
B. These
waves give us clues to
the composition of the Earth
III. Types of waves
A.
P-waves (primary waves)
1. Compress and expand rock
2. Are the fastest
3. First waves to register on seismograph
Types of waves (cont.)
B.
S-waves (secondary waves)
1. Vibrate up and down or side to side
2. 2nd waves to register on a seismograph
S Waves
IV. Measuring Earthquakes
A. Seismograph
1. Device which measures seismic waves
Clicker ?’s 1-9
V. Movement along a fault
boundary
A.
Transform-fault boundary –
plates are sliding past one another
EX. San Andreas
fault in California
★ Earthquakes caused by shearing forces
V. Movement (cont.)
B. Divergent Boundary
1. two plates are moving apart
 Plate A
Plate B

2. Forms rift valleys - large spreading
valleys
or
3. Creates sea floor spreading- a rift valley
on sea floor
4. Caused by tensional forces
Divergent Boundaries
Divergent Boundaries- can
observe reverse polarity
V. Movement (cont.)
C. Convergent Boundaries
1. 2 plates move towards each other
Plate A 
 Plate B
2. Leads to subduction- one plate
(usually oceanic crust)
goes beneath the other
(continental crust).
a. Caused by compressional forces
Convergent Boundaries
Convergent Boundaries
Ex: Andes Mountains
in S. America
(Still growing because
of subduction)
3. ★Common place to find
volcanoes
Ex: Cascade Range
(Mt. St. Helens & Mt. Rainier)
VI. Earth’s internal layers
A.
B.
Geologists did research with seismic
waves
Concluded that the Earth’s
interior is layered.
Earth’s internal layers
SKETCH THIS!
Earth’s internal layers
A. Core1. Composed
mostly of iron
and nickel
2. Inner Core
 very hot

solid Fe & Ni
due to high
pressure of the
Earth
The Core (continued)

3. Outer Core
 less pressure
from the earth
 liquid Fe & Ni
 Flow in the outer
core generates
an electric
current that
powers the
Earth’s magnetic
field.
B. The Mantle
A.
B.
Rocky layer
About 3000 km thick
Mantle (cont.)
a. Lower mantle
b. Upper mantle –
two sections
Upper mantle (cont.)
1. Asthenosphere - behaves in a semi-fluid manner
Source: http://www.uwsp.edu/geo/faculty/ritter/images/lithosphere/tectonics/earth_structure.jpg
Upper mantle (cont.)
Lithosphere- rigid and brittle
Legend
Lithosphere
&
Crust
Mantle & &
Asthenosphere
Outer Core
Inner Core
&
Thickness
of layers.
C. The Crust
1.
2.
Uppermost portion of the lithosphere
Two types of crust
a. Oceanic crust – below ocean, dense
about 10 km thick
The Crust (cont.)
b. Continental crust – below land, less dense
about 20-60 km thick
Evidence that supports the
theory of Continental Drift
1. Geologic (rock)
2. Biologic (life)
3. Climatological (past weather)
4. Continental Shelves fit together well
Tectonic Plates
moving sections of the lithosphere
on which continents lie
Major Tectonic Plates
Clicker ?’s 1-9 (Continental Drift and Faults)