Plate Tectonics

What is Plate Tectonics? An explanation of how the continents formed – going from one big land mass to individual continents Also explains movements of the Earth that have created volcanoes and earthquakes A THEORY that plates below the surface of the Earth move and interact with each other

Types of plate boundaries Divergent – process of the sea floor spreading apart Examples  Mid-Atlantic Ridge & East Pacific Ridge

Types of plate boundaries Convergent – ocean-ocean subduction Examples  Islands of Indonesia, Mariana Islands

Types fo plate boundaries Convergent – ocean – continent subduction Examples  Western coast of South America

Types of plate boundaries Convergent – continent – continent collision Example  Himalayas

Types of plate boundaries Transform – plates sliding past each other Examples – San Andreas Fault(California); North Anatolian Fault (Turkey)

Why do plates move? Mantle convection - Heat coming up from the mantle (under the first few layers of the Earth) Ridge push – actually the cooling of the rock; rock spreads out Slab pull – a force from on the sinking plate (plate going down) on the rest of that same plate

Ancient history………. Scientists belive that all continents were once one big continent. They called this continent PANGAEA. (200 million years ago)

More ancient history…….. Plates started moving – land started shifting (moving) Laurasia & Gondwana (180 million years ago)

Younger ancient history….. Continents begin moving apart at 65 million years ago we are able to see some structures we would be able to recognize.

Modern day……

Continental growth …. Each continent is made up of ancient rock call CRATON.

Continental growth Continents grow now by having deep sea sediments added on to the continent – this is added to the edges of the continent when an oceanic plate moves underneath a continental plate . Sediments scrape off and stay on the continent.

Continental growth Continents also grow through igneous rock – volcano eruptions and the rocks that are thrown from the volcano

Continental growth Continental growth also happens through river sediments – sediments are small pieces of dirt that end up in places – an example is the Mississippi River Delta

Terranes A TERRANE is a large block of lithospheric plate that has been moved Can be over a large distance of thousands of miles Attaches to the edge of a continent