Download PANGEA

SCIENCE DETECTIVE® A1
Earth Science
35-Plate Tectonics: Mountains, Volcanoes, and Earthquakes
14What causes these plates to move?
A 1Earth's entire crust, which includes the
continents and ocean basins, is constantly
moving. 2Parts of the crust slowly move into,
under, or away from each other. 3The drift of the
continents is so slow (about 1.5 inches per year)
that it is not noticeable unless it's viewed over
millions of years.
SHeat from deep inthe Earth's interior causes
the rock in the mantle to become hotter and
rise upward. 16Then it squeezes between the
edges of two plates, or plate boundaries. 1q-his
forces the ,plates apart. ÿhis process constantly
pushes the plates farther and farther apart.
5Think of the continents as large pieces of a
E ÿgPlaces where plates move apart are called
divergent boundaries. 2°This type of plate
movement is responsible for seafloor spreading,
puzzle. 6Do they all fit together? 7Look closely at
which is how the Mid-Atlantic Ridge and .East
their coastlines.
Pacific Rise were formed.
B 4Have you ever put together a jigsaw puzzle?
F =ÿAt convergent boundaries, the plates are
actually moving toward each other, causing a
collision. ÿ2When there is a continent on both
sides of the plates, the collision causes the crust
to crumble, fold, tilt, or lift, forming mountains.
23The Himalayan Mountains formed along a
convergent boundary. 24Volcanoes are also
found at convergent boundaries. 25As one plate
slides under another, hot rock material in the
upper mantle melts and becomes magma. 261t
can then erupt through cracks, producing volcanic
PANGEA
mountains.
C 8In 1912, Alfred Wegener, a German scientist,
wrote a book called The Origins of Continents
and Oceans, where he explained how Earth's
continents had fit together at one time as
one gigantic continent. 9He called this huge
continent Pangea, which means "all lands." ÿ°His
hypothesis is now known as continental drift.
G 27Tile San Andreas fault is a famous example
of a transform fault boundary. 28Faults are
huge cracks in the Earth's crust. 29This type of
boundary occurs when plates slide past each
other in different directions.without moving
up or down. 3°Sometimes the motion is very
gradual and occasionally it is very sudden. 3ÿAn
earthquake is the rigorous shaking of the Earth
D HEarth's crust and outer mantle form the
lithosphere° ÿq-he lithosphere is broken into
pieces called tectonic plates. ÿ3-I-he tectonic
plates float on the asthenosphere, found
right below the lithosphere.
"
COÿfVERGENT
FL,ÿTÿOLrÿD,ÿy
• ÿaÿ--yÿ ÿ
. ÿ--"
LAT'E
due to sudden plate movements.
Plate Te onics Questions
1. Describe the movement of the Earth's crust
2. Who was the scientist who called the one large continent Pangea?
3. What was his hypothesis called?
4. What two layers make up the lithosphere?
5, Which layer makes up the tectonic plates?
6. The tectonic plates float on the
7. What causes plates to move?
8. Divergent boundaries
- Describe their movement:
• Landforms created (2):
° Example is:
,
Convergent boundaries
• Describe their movement:
• Landforms created (2):
• Example is:
10. Transform boundaries
• Describe movement
° Result (geological event):
o Example is:
C