Dynamic Earth

Geosphere/Lithosphere

Earth’s Layers

Plate Tectonics

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/.../1269/1300245/18fig12.gif

Fig. 1.6

Sea Floor Spreading

www.adonline.id.au/plantevol/continents.htm

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

www.ig.utexas.edu/.../plates/pt.info.htm

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

www.cas.sc.edu/.../ 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

Volcanoes

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.

Volcano Formation

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 Flowfast-moving currents of hot gas and rock which travel away from the volcano at speeds more than 50mph.

Earthquakes and Tsunamis

Earthquake Damage

• landslides/mudslides• fires• ground shaking• tsunamis

Tsunamis

Tsunami Damage

Warning System

The Epicenter

The Atmosphere

Hydrosphere

Statistics for the earth's water supply:

• Oceans 97.61%•  Polar Ice & Glaciers 2.08•  Groundwater 0.29•  Freshwater lakes 0.009•  Saline Lakes 0.008•  Soil Moisture 0.005•  Rivers 0.00009•  Atmosphere  0.0009

The Hydrologic Cycle

The Biosphere

The Biosphere Includes All Life on Earth

• a zone that extends from the ocean floor upward several miles into the atmosphere

• The biosphere includes all living organisms on Earth