Standard 7a Notes Describe how matter and energy are cycled within earth’s systems: Identify the energy source and process that moves plate tectonics. Identify and predict how plate tectonics, glacial movement, weather and volcanic activity shape earth’s crust; past, present, and future.

Evidence for Plate Movement Current continents appear to fit together Abraham Ortelius – Floods pushed them away Alfred Weneger – Continental Drift & “Pangea” Fossils similar on different continents - Mesosaurus and Glossopteris (plant) Rock formations: rocks from Appalachian Mountains similar to Greenland. Climate: Evidence of large glaciers in warm climates - Must have all been near a pole at one point Mesosaurus could not have crossed the atlantic, the continents must have touched at some point. Glossopteris (plant) could not have lived in the varied climates that were on Africa, South America, Australia, AND Antarctica. )

Evidence for Continental Drift (Today) We can add… Seafloor Spreading Volcanic Activity Mountain building Earthquakes near plate boundaries GPS Movement

Continental Drift Now Billions of years ago Gif: http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/earth.htm

Plate Tectonics Theory of Plate Tectonics – Earth’s lithosphere is divided up into enormous slabs called tectonic plates that are constantly in motion relative to each other.

Earth’s Current Plates

What is next?

Causes for plate movement Convection – the movement of hot liquids Matter is heated, it expands and becomes less dense, therefore lighter. Lighter (hotter) material then floats to the top and cooler material sinks to the bottom. Gif: http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/earth.htm Hot = Yellow Cool = Blue Look for circular movement!

Where does the heat come from? Radioactivity – Unstable isotopes (atoms with too many or too few neutrons) split apart to create energy Remaining thermal energy created from the collision of fast-moving, massive objects during the formation of the earth Where else does earth get energy? SUN: (Affects atmosphere more than the earth’s interior)