The Theory of Plate Tectonics Chapter 5 Lesson 3
What is the Theory of Plate Tectonics? The theory of plate tectonics states that Earth’s plates are in slow, constant motion, driven by convection currents in the mantle.
Transform Convergent Divergent
Plate Boundaries Earth’s plates meet at boundaries. Along each boundary, plates move in one of three ways. 1. Apart – Divergent boundary 2. Together- Convergent boundary 3. Past each other – Transform boundary Plates move between 1-12 cm per year, which is about how fast your fingernails grow. Faults- are breaks in Earth’s crust where rocks have slipped past each other
Divergent boundaries – two plates moving slowly apart form a rift valley
New basaltic magma rises to the surface along the ridge forming new oceanic crust
Convergent Plate boundaries – plates moving together Three types of convergent boundaries 1. Oceanic crust meets Oceanic crust 2. Oceanic crust meets Continental crust 3. Continental crust meets Continental crust
Ocean-Ocean- forms a trench – more dense material will sink under the less dense material
Japan is an example of an Island Arc system Trench Island arc
Ocean crust converging with continental crust Results in volcanic arc and a trench
Oceanic - continental convergence E.g. Andes mountains
Continental-continental convergence
The Andes
The sub-continent of India has collided with the Eurasian continent to form the Himalayas
Eurasian Plate Indian Plate
Transform Boundaries are where two plates slip past each other moving in opposite directions. Earth quakes result from this type of boundary