Post on 14-Dec-2015
transcript
CATALYST
• Describe the 3 types of plate boundaries.• Explain how
convection currents move plates.
1. Describe 1 type of plate movement.
OBJECTIVES
DATE: 02/10/2015
Plate Tectonics
• Earth’s crust is divided into 12 major plates (tectonic plates) which are moving in various directions.• Plate Boundary–Where 2 plates meet
Types of Plates
Continental Crust• Thick (10 - 70 km)• Less Dense• Mostly very old
Oceanic Crust• Thin (~7 km)• More Dense• Young age of rocks
Plate Boundaries
1. Divergent Boundaries2. Convergent Boundaries
a. Oceanic-Oceanicb. Oceanic-Continentalc. Continental-Continental
3. Transform Boundaries
1. Divergent Boundaries
• 2 or more plates separate or pull apart• Magma rises between the plates and
makes new rocks• Formation of ridges (in the ocean) and
rift valleys (on the continents)
2. Convergent Boundaries
• 2 or more plates moving towards each other• 3 types
a. Oceanic-Oceanicb. Oceanic-Continentalc. Continental-Continental
2a. Oceanic-Oceanic
• Collision of 2 oceanic crusts• One oceanic crust will
eventually slide under the other
What will happen to the oceanic plate when it sinks?
2b. Oceanic-Continental
• Collision between an oceanic plate and a continental plate• Oceanic crust is more dense
than continental crust so…–Oceanic crust sinks below
continental crust
2b. Oceanic-Continental
Continental
Oceanic
What will happen to the oceanic plate when it sinks?
SUBDUCTION
2c. Continental-Continental
• Collision of 2 continental plates• Similar density, so neither subducts• Formation of mountains
2c. Continental-Continental
• Example: Indian-Australian Plate vs. Eurasian Plate–Collision formed
Himalaya Mountains
3. Transform Boundaries
• 2 plates slide horizontally past each other• Forms long lines in the Earth
(faults) and deformation of the land