CATALYST OBJECTIVES DATE: 02/10/2015 Describe the 3 types of plate boundaries. Explain how convection currents move plates. Describe 1 type of plate movement.
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
Plate Tectonics
Types of Plates Continental Crust Oceanic Crust Thick (10 - 70 km) Less Dense Mostly very old Thin (~7 km) More Dense Young age of rocks
Convergent Boundaries Plate Boundaries Divergent Boundaries Convergent Boundaries Oceanic-Oceanic Oceanic-Continental Continental-Continental 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)
1. Divergent Boundaries
1. Divergent Boundaries
1. Divergent Boundaries
2. Convergent Boundaries 2 or more plates moving towards each other 3 types Oceanic-Oceanic Oceanic-Continental Continental-Continental
What will happen to the oceanic plate when it sinks? 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?
2a. Oceanic-Oceanic Subduction When a more dense plate goes under (subducts) a less dense plate
2a. Oceanic-Oceanic
Trenches and Island Volcanoes form at this boundaries 2a. Oceanic-Oceanic Trenches and Island Volcanoes form at this boundaries
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 What will happen to the oceanic plate when it sinks? SUBDUCTION Oceanic
2b. Oceanic-Continental Trenches and Land Volcanoes form at these boundaries
Plate Tectonics
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
2c. Continental-Continental
3. Transform Boundaries 2 plates slide horizontally past each other Forms long lines in the Earth (faults) and deformation of the land
3. Transform Boundaries
3. Transform Boundaries Example: San Andreas Fault, CA
3. Transform Boundaries
But what is causing these plates to move? Convection Currents!