Transcript Plate Tectonic Notes - Bear Branch Junior High School

Plate Tectonic Notes
I. Continental Drift Theory
A. proposed by Alfred Wegener in 1912
B. states that all continents were once one
supercontinent (Pangaea) and have since “floated”
apart over time
C. Evidence to support theory
1. fossil records are similar on different continents
2. land forms such as mt. ranges and mineral
deposits line up
3. coastlines of current continents appear to “fit
together” like a puzzle
II. Theory of Plate Tectonics
A. states that the earth’s crust
is broken into large moving
pieces (plates) to which the
continents are attached.
B. Why Change the Theory?
1. new technology allows
scientists to discover new
information
a) sonar
b) SCUBA
c) submarine improvements
C. New Evidence
1. sea-floor spreading
2. earthquakes and volcanoes
3. actual recorded movement
C. 16 plates (* means major plate)
1.
2.
3.
4.
5.
N. American*
Eurasian*
Juan De Fuca
Caribbean
Cocos
6. Arabian
7. Phillippine*
8. S. American*
9. Caroline
10. African*
11.
12.
13.
14.
15.
16.
Indo-Australia*
Fiji
Nazca*
Pacific*
Scotia
Antarctic*
III. Plate Boundaries
A. locations where two plates meet
B. where the forces that shape the earth’s surface occur
1. Constructive forces – create landforms
2. Destructive forces – destroy landforms
C. three different types
1. Divergent
a) plates move away from each other
b) sea-floor spreading & ridges
c) new crust is formed at this boundary type
d) mid-Atlantic Ridge in Atlantic Ocean
2. Convergent
a) plate move toward one another
b) subduction- one plate forced underneath another
> deep trenches, coastal mt. ranges, volcanoes
> Andes Mts on west coast of S. America
c) collision – both plates push upward
> large mt ranges, earthquakes
> Himalaya mt range in northern India
3. Transform
a) plates move past one another in different directions
b) faults visible at surface, large earthquakes
c) San Andres Fault in California
Boundary
Movement
Divergent
Plates move
AWAY from one
another
Convergent
Collision
Plates move
TOWARD each
other and BOTH
push upwards
Picture
Landform(s)
& Examples
Landforms:
Mid-ocean ridges &
rift valleys
Example:
Mid-Atlantic Ridge
Landforms:
Large mountain
ranges w/ lots of
earthquakes
Example:
Himalayan Mts in
India
Landforms:
Convergent
Subduction
Transform
Plates move
TOWARD each
other and one
plate gets pushed
under the other
Plates move past
one another in
opposite
directions
Deep ocean
trenches, coastal
mt. ranges &
volcanoes
Example:
Andes Mts in South
America
Landforms:
Faults that are
visible on land
Example:
San Andres Fault in
California
divergent boundary
transform boundary
convergent / subduction
boundary
convergent / collision
boundary