1. Formation of the earths surface Geosphere formed by accretion and density stratification Surface stays molten for millions of years Continents formed as crust cooled Over time geologist have theorized what the continents looked like over the last 500 billion years.

2. Wegeners Continental Drift Theory All continents were once joined together as a supercontinent called Pangea Evidence: Similar shorelines Fossils on opposite coasts match Mountain ranges end on one continent and pick up on another Same age rocks found on separate continents Climate changes seen in the development of coal deposits Glacial deposits found on South America and Africa Problem? No mechanism for the changes. 3. Finding A Mechanism Wegeners data was very well accepted but without a mechanism the theory was abandoned for decades In the early part of the 20th century the development of sonar enabled scientists to see the terrain of the ocean floor The discovery of the mid ocean ridge and the spreading of the sea floor helped to bring about the development of the currently accepted theory. 4. Plate Tectonic Theory The crust is broken into pieces and is moved by the movement of the asthenosphere below it. What causes the asthenosphere to move? 5. Properties of Materials First we must understand the properties of materials http://www.youtube.com/watch?v=3qAs1Nt0Fjk What is a solid? Holds a shape Molecules are tightly packed together What is a liquid? Takes the shape of its container Molecules are more loosely collected and can move Ability to flow from one container to another What is a gas? Expands to fill the container Molecules are widely spaced Can flow, expand and be compressed 6. Is it a solid or a liquid? Exploration: Use these two substances and determine the properties of each . Silly putty Cornstarch (mix 3 Tablespoons of cornstarch with 1 T of water the mixture should be very hard to stir but will flow out of a cup if it gets too watery add a little more corn starch) Go ahead and watch the podcast that I have on how this looks it will help! Go ahead and do the exploration nowit will make the rest of the lecture make more sense Besides its FUN!!! 7. Properties of Layers Crust solid conducts heat Upper Mantle solid with liquid properties convects heat Lower Mantle solid rock conducts heat Outer Core liquid metal (less pressure than inner core allows metal to melt) Liquid convects heat Convection is the movement of heat as a flow of molecules Inner Core solid iron and nickel with strong nuclear fusion producing intense heat Solid conducts heat conduction is the movement of heat from molecule to molecule 8. Convection in Asthenosphere Heat from core changes the density of the material. As temp rises density decreases and fluid rises As temp decreases, density rises and fluid sinks This movement is called a convection current which moves the asthenosphere and thus the crustal plates attached to it. 9. Fig. 1.7, p.7 10. Convection Videos https://www.youtube.com/watch?v=WEDU tS0IMws https://www.youtube.com/watch?v=yt_K_b fKxTc