Presentation on theme: "Dynamic Earth Geosphere/Lithosphere Earth’s Layers."— Presentation transcript:
Earth’s Internal Heat Engine Very hot material from the core heats the materials above. The hot material expands and moves upward, and cools as it nears the surface. The cold crust is then pushed back down at plate boundaries. Image from: wps.prenhall.com/.../1269/ /18fig12.gif Fig. 1.6
Sea Floor Spreading
Movement of the Continents: The continents have not always been where they are now. Over time they drifted across the surface of the Earth, and continue to do so today.
Pangea ~250 MYA
Gondwana ~200 MYA
Plate motions: The length of the arrows in the image below shows how fast the plate is traveling in the direction indicated. So how do we know these velocities so precisely?
GPS: Global Positioning System: A network of 24 satellites orbit the earth for use with this system.
Example of a convergent plate boundary in Nepal. peace.sandiego.edu/ programs/nepal.html
pubs.usgs.gov/publications/ graphics/FigS8-2.gif Example of a Continent/continent collision: Indian and Eurasian plate
images/GSG_CD/ earthquake.usgs.gov Most divergent boundaries are out in the ocean. But there are a few places they actually cross land. These regions are known as “Rift zones”.
San Andreas Fault
How Volcanoes Form Deep in the earth it is so hot that rocks melt. The melted rock is called magma. The magma is lighter than the rocks around it so it rises. Sometimes it finds a crack or hole in the earth’s crust and bursts through.
Why do volcanoes erupt?
Pressure builds deep in the earth where the magma is. Suddenly the gases escape and violently explode. It is kind of like toothpaste squirting out of a tube when you give it a hard squeeze.
Pyroclastic Flow fast-moving currents of hot gas and rock which travel away from the volcano at speeds more than 50mph.