Plate Tectonics

The Earth’s 4 Layers 1.Inner Core: Center, made of solid iron and nickel km 2.Outer Core: Made of liquid iron and nickel km 3.Mantle: Rich in iron, magnesium, and silicon. Melted at shallower levels km 4.Crust: Solid rock, km

The Crust Made of a number of rigid, but moving plates. Plate Tectonics: The study of the formation and movement of these plates.

Why do the plates move? The plates are part of the lithosphere –Lithosphere: The crust and uppermost part of the mantle. The lithosphere rests on top of the asthenosphere, made of partially melted rock. This allows it to move slowly and form convection currents

Rising of warm material and sinking of cold material in a cycle Convection Currents

Evidence for Plate Tectonics Continental Drift: Alfred Wegener, proposed continents were once a super continent (Pangaea) Certain coast lines fit together like puzzle pieces

Continental Drift Fossils of animals are found on separate continents

Plate Types 2 different plate types: –Oceanic: When a plate is under the ocean. Pacific Plate Nazca Plate –Continental: When a plate has land on it. Antarctic Plate Eurasian Plate Some plate have oceanic and continental areas: North American Plate Indian Plate

3 Plate Boundaries Diverging: Plates move away from each other. Converging: Plates come together. Sliding/Transform: Plates move past each other.

Diverging Boundaries Most occur at crests of oceanic ridges Constructive Plate Margins

Oceanic Ridge Forms  seafloor is elevated The ridges have deep valleys in them called rift- valleys, the place where new rocks form Seafloor Spreading  plate tectonics produce new oceanic lithosphere. Diverging Boundaries

Converging Boundaries 3 converging boundary types –Continental-Continental collision boundary –Continental-Oceanic –Oceanic-Oceanic subduction boundary

Form larger continent Forms Mountain Ranges Destroys Ocean Floor Converging Boundaries Continental-Continental Collision Boundary

One plate is pushed underneath the overriding plate Create deep-sea trenches Ocean crust is destroyed. Form Volcanoes Converging Boundaries Subduction Boundaries

Subduction: Ocean to Ocean

Subduction: Ocean to Land

Transform/Sliding Faults Create a fault: a break or crack in the crust along which movement occurs.