1. A new Paradigm… Plate Tectonics

2. PANGEA
In 1912 Alfred Wegener suggested that all continents were once connected about 300 million years ago into a supercontinent called PANGEA.

3. Continental Drift Theory
Over time, he said they drifted apart, but he could not provide the mechanism that would explain this.

8. The Structure of Earth The Earth is made up different types of layers.
The Lithosphere is divided into large plates.
Convection currents in the asthenosphere move the plates.

10. Crust: Rigid surface of the Earth. It can be between 0-100 km thick
Layers of the Earth
Crust: Rigid surface of the Earth. It can be between km thick
Continental Crust: Thicker parts of the crust (above the ocean) mainly granite
Oceanic Crust: Thinner parts of the crust under the ocean, made of basalt.
Mantle: Between the crust and the core. Largest volume of the earth. Mg, Fe, O, Si are key elements.
The crust and mantle are called the lithosphere. (sphere of stone)

11. Upper Mantle: Solid part of the mantle
Lower mantle: semi-solid and capable of movement (called the asthenosphere).
Core: Outer part is liquid km thick. Inner is solid and mostly nickel and iron. *Believed to control the Earth’s magnetic field.

12. Tectonic Plates
The lithosphere is broken into 9 large, rigid pieces called plates.
The plates are all moving in different directions and at different speeds (from 2 cm to10 cm per year)

20. Pangaea