Earth is over 1200 km thick and has four layers. – Crust - outer solid rock layer (granite on land, basalt in oceans) – Mantle – thickest layer, mostly solid except for upper mantle that flows like “thick toothpaste” – Outer Core - made up of liquid iron and nickel – Inner Core - mostly solid iron, at high temperature and pressure FEATURES OF PLATE TECTONICS:

The Lithosphere is the crust and upper part of the upper mantle and is made up of tectonic plates The lithosphere floats on the asthenosphere FEATURES OF PLATE TECTONICS

The Asthenosphere is the molten (liquid) layer of the upper mantle Heat to keep the asthenosphere molten comes from radioactive elements Without radioactivity our planet would be cold and dead…. FEATURES OF PLATE TECTONICS

Continents, attached to the tectonic plates, float in the magma of the asthenosphere. – As magma is heated in the asthenosphere, convection currents drive plate movement. – Rising magma reaches the surface at ridges (in the oceans) or rifts (on land). PLATE MOTION

DATA BOOKLET PAGE 6-7 Tectonic plates are all moving at the same time There are 25 tectonic plates and many smaller ones

Tectonic plates are all moving at the same time. There are 12 large tectonic plates and many smaller ones. Data Booklet: p. 7 PLATE MOTION USGS

PLATE INTERACTIONS Tectonic plate boundaries, and their relative movement to each other.

DATA BOOKLET P. 6-7

Subduction happens where plates meet. The denser oceanic plate subducts (gets pulled under) the less dense continental plate. – Large earthquakes and volcanoes are found in subduction zones. PLATE SUBDUCTION

3 FORCES THAT DRIVE PLATE TECTONICS 1. Convection Currents 2. Ridge Push 3. Slab Pull

The Big Picture

BBC POWER OF THE PLANET Continental Drift

PLATE BOUNDARIES 1. Please collect the assignment for 17.4 and part of 18.1 from the front of the room 2. We will work through the first column of the assignment together 3. Work with your neighbours to complete the assignment 4. The assignment is Due Next Class

HOMEWORK Read 17.4 CYU Q’s 2,3,5-7,9,13

A plate boundary is an area where two plates touch. The way the plates interact is based on the type of plate and the direction the plates are moving. PLATE INTERACTIONS

Divergent plate boundaries – where plates spread apart Convergent Plate boundaries – where plates come together Transform plate boundaries – where plates move past each other PLATE INTERACTIONS

1. Divergent plate boundaries are areas where plates are spreading apart. – Examples: Ocean ridges and continental rifts – The Mid-Atlantic Ridge is the longest mountain range on Earth. DIVERGENT PLATE BOUNDARIES

Convergent plate boundaries are areas where plates move towards each other. There are 3 kinds; – Oceanic-continental – Oceanic-oceanic – Continental-continental CONVERGENT PLATE BOUNDARIES

The oceanic plate subducts under the continental plate, forming a trench. Cone-shaped volcanoes can form from magma seeping to the surface. Earthquakes happen when subduction, ridge push, and slab pull build pressure. OCEANIC-CONTINENTAL PLATE CONVERGENCE

The cooler, denser plate will subduct under the less dense plate. – Convergence may make a volcanic island arc, Ex. Japan, Indonesia, and Alaska’s Aleutian islands OCEANIC-OCEANIC PLATE CONVERGENCE

Since both are continental plates, their densities are similar. – As they collide, their edges fold and crumple, forming mountain ranges. CONTINENTAL-CONTINENTAL PLATE CONVERGENCE

HIMALAYA’S The Himalayas are the world’s youngest (and tallest) mountain range, formed as Asia and Africa plates meet 40 million years ago. They are still growing taller today.

Where plates move past each other in opposite directions – Usually are found near ocean ridges – Since rock slides past rock, no mountains or volcanoes form TRANSFORM PLATE BOUNDARIES San Andreas fault