Download Plate tectonics

Internal Forces Shaping the
Earth Updated 8/21/12
•
•
•
•
Earth’s Structure:
1) Core: solid metallic center of the earth.
2) Mantle: 1800 miles thick
3) Crust: thin layer of rock at the surface
PANGAEA
• Pangaea: 200 million years ago there was 1
super continent.
• Continental Drift: Theory that
supercontinent separated and drifted apart.
Evidence of Pangaea
• Fossils-distribution of ancient plants and animals
• Paleoclimatology-sedimentary rocks indicate
climate and latitude of original placement
• Rock magnetism-rocks, especially volcanic rocks,
preserve a record of the orientation of the earth’s
magnetic field
• Sea floor spreading-formation of the Mid-Atlantic
Ridge
Fossil Support
Plate Movement
• Tectonic Plates are enormous pieces of the
earth’s lithosphere that are slowly moving
• Plates move along 3 boundaries:
 Divergent: plates move apart, spreading
horizontally
 Convergent: Plates collide, causing one plate to
go underneath or both edges crumble
 Transform: Plates slide past one another
•
•
•
•
•
•
•
•
•
•
•
•
•
Plate Absolute Velocity (cm/yr)*
Antarctic
~2.05
African
~2.15
Arabian
~4.65
Caribbean
~2.45
Cocos
~8.55
Eurasian
~0.95
Indian
~6.00
Nazca
~7.55
North American
~1.15
Pacific
~8.10
Philippine
~6.35
South American
~1.45
EXAMPLES
• Divergent: between Saudi Arabia and
Egypt: plate movement is causing the Red
Sea to become wider than ever before.
• Convergent: Himalayas are caused by the
Indian plate crashing into the Asian plate.
• Transform: San Andres Fault, California.
Divergent Plate Boundary
Convergent Plate Boundary
Transform Plate Boundary
Plate Boundaries
EARTHQUAKES
• Earthquakes: as plates grind or slip past
each other at a fault, the earth shakes or
trembles.
• Seismograph: Measures size of waves
created by earthquake.
• Epicenter: -Location on the earth where
earthquake begins.
• Richter Scale: C. E. Ritchie developed a
scale to measure amount of energy.
• Tsunami: Earthquake below the ocean and
can cause a giant wave.
• Volcano: An opening in the earth’s crust
where Magma and gases escape. Most are
found near the tectonic plate boundaries.
• Magma that reaches the earth’s surface is
called lava.
• Ring of Fire: A zone around the rim of the
Pacific Ocean where most active volcanoes
are found.