Get out your lab and your Ch. 7 Section 3 Notes and on your small paper answer the following question: What do you think is the driving force that causes the Earth’s tectonic plates to move? Today’s Schedule 1. Ch. 7 Section 3 Notes/Discussion 2. Review Sea-Floor Spreading Lab

What We Know So Far

What We Want To Know What causes the plates to move? THE answer to this question we believe is: convection currents in the mantle. animation

Convection Convection- heat transfer by the movement of currents within a fluid Caused by differences of temp. and density within the fluid

Convection Currents in Earth 1. What is the heat source? 2. What is flowing? Heat from the core and the mantle itself causes convection currents in the mantle. Google Image Result for

Convection Currents in the Earth Animation As the convection currents move through the mantle, it causes the plates to move in the lithosphere.

What do you see here? Plate Boundaries

Plate Boundaries Divergent Boundary- place where 2 plates move apart or diverge. Most DB’s are at mid-ocean ridges. On land DB’s form deep valleys called rift valleys Fig Evolution of a Divergent Plate Boundary animation

Convergent Boundary Place where 2 plates come together, or converge. Oceanic plate + Continental plate = subduction Continental plate + Continental plate = mountains OptIPuter Outreach

Subduction at Trenches Deep-ocean trench- underwater canyon where ocean crust sinks into the mantle. Subduction- process by which ocean crust sinks beneath a deep-ocean trench and back into the mantle Subduction Animation - Earthguide Online Classroom

Transform Boundary Place where two plates slip past each other in opposite directions. Transform Boundaries = Earthquakes Observe animations of processes that occur along plate boundaries. animation

Matching Game land masses have slowly moved over time Plates move on top of asthenosphere Two plates slip past each other in opposite directions Happens at divergent boundaries, allows magma to rise to the ocean floor Two plates collide with each other Two plates separate with each other Convergent boundary Sea-floor spreading Plate tectonics Continental drift Divergent boundary Transform boundary

Plate Boundaries Contest Transform Divergent Convergent

Ch. 7 Section 3 The Theory of Plate Tectonics Things you should know: what plates are, directions plates move, and some landforms that plate movement creates. Now, you need to figure out what causes the plates to move. Observe these demonstrations to discover the answer.