Plate tectonics : chapter 9.3 & 9.4 Plate tectonics : chapter 9.3 & 9.4

Temperature In core, C Radioactive elements, high pressure create the high temps Convection currents in the mantle move the continents

Convection currents Convection currents occur when a gas or a liquid is heated from the bottom. Convection currents occur when a gas or a liquid is heated from the bottom. Warm gasses & liquids are less dense than cold. Warm gasses & liquids are less dense than cold. The warm substance rises and the cold sinks. The warm substance rises and the cold sinks. This process is responsible for air, ocean, & mantel currents. This process is responsible for air, ocean, & mantel currents. Pair share: look at the picture are the two oceanic plates moving towards or away from each other?

Plates move as they ‘float’ on a moving mantle

Lithosphere & Asthenosphere Made of the crust and the upper mantle- 60 miles thick Divided into 7 large tectonic plates Continental drift is the movement of the plates over time

Plate boundaries Divergent : plates move apart Magma comes up to fill the gap: volcanoes, rift valleys, new crust formed Pair share: show your partner with your hands how divergent plates move.

Mid-Atlantic ridge: a divergent plate boundary N and S America were separated from Europe, Africa

Convergent boundary Plates move towards each other subduction when the denser oceanic plate dives below the continental plate. Forms ocean trenches, mountain ranges, and volcanoes. ex: Andes, Cascades mtns. Pair share: show your partner with your hands how convergent plates move.

Colliding continental crusts Both plates push upwards Indian plate smashes into the Asian plate Himalayas form: world’s tallest mountains Mt. Everest

Transform faults 2 plates slide past each other. Pacific Plate slides N past the North American plate San Andreas fault Pair share: show your partner with your hands how transform faults move.

Review 1.Convection currents occur because warm liquids are _________ than cold liquids. 2.Divergent plates move ________ ______ each other. 3.Convergent plates move ______ _____ each other.