1. Structure of the Earth Geology 12 Ms. Pushie CHS - 2010

2. Structure of the Earth Earth was formed roughly 4.6 billion ears ago and for a long time was entirely molten. The various materials (elements) that make up the earth were stratified (separated) according to their density. The densest elements formed the core and the lighter elements floated to the surface.

3. Structure of the Earth As the Earth gradually cooled the surface solidified (became solid) to form a crust. Scientists are not 100% sure of the origin of the water, one theory is the steam from volcanoes cooled and became the water of the Earth

4. The Earth – top layer 1. Crust - thin and light layer, made up of Tectonic Plates composed of basalt and granite. The crust is where we live! 5-40 km thick. Continental crust- Where we are everyday! Is made up of less dense granite. Oceanic crust -The bottom of the ocean floor. Is thinner more dense basaltic material.

5. Why are the Continents above the Ocean floor? Because of density - The layering of the earth based on differing density. Land with greater density will sink, those that are lighter float. Continental crust is lighter approx 2.7 g/cm 3. Oceanic crust is heavier at 2.9 g/cm 3 Continents are 100m above sea level, Ocean floor are about 4000m below sea level.

6. 2. Mantle - located beneath the crust. The mantle is more dense and rigid than the crust, a rocky layer. 2885 km thick. The mantle has 2 parts, upper and lower. - upper mantle- slow convection currents of magma causes Continental Drift. The Earth – middle layer

7. The Earth – inner 3. Core- located beneath the mantle. Is very hot and dense. Composed of iron and nickel. This is the hottest and heaviest layer. 2270 km thick, there are 2 parts: –The outer core is liquid capable of flow and source of the Earth's magnetic field. – The inner core is solid Iron Nickel.

8. Animation of earth structure http://scign.jpl.nasa.gov/learn/plate1.htm

9. Earth’s Crust – draw me!

10. Earth's Internal Structure The Earth's interior is characterized by a gradual increase in temperature, pressure and density with depth. At 100 km depth, the temp is ~1300°C. At the Earth's center, the temperature is >6700°C.