1. © 2007, John Wiley and Sons, Inc. Physical Geography by Alan Arbogast Chapter 12 Earth’s Internal Structure, Rock Cycle, and Geologic Time Lawrence McGlinn Department of Geography State University of New York - New Paltz

2. © 2007, John Wiley and Sons, Inc. Earth’s Internal Structure, Rock Cycle, and Geologic Time Earth’s inner structure Rocks and minerals in the Earth’s crust Geologic time Basic geomorphology of continents and ocean basins

3. © 2007, John Wiley and Sons, Inc. Earth’s Interior

4. © 2007, John Wiley and Sons, Inc. Core to Crust

5. © 2007, John Wiley and Sons, Inc. Earth’s Inner Structure Major Layers (outside-in): Lithosphere Upper Mantle Lower Mantle Outer Core Inner Core

6. © 2007, John Wiley and Sons, Inc. Inner Core Radius 760 mi. Mostly solid iron w/bit of nickel Temp 3200º-5200º C Tremendous pressure keeps inner core solid

7. © 2007, John Wiley and Sons, Inc. Outer Core 1398 mi. thick Outer core is liquid – molten iron Similar temp to inner core, but less pressure Generates >90% of Earth’s magnetic field Magnetosphere protects Earth from solar wind Mag. field likely due to circulation in outer core that create electrical currents

8. © 2007, John Wiley and Sons, Inc.Mantle Surrounds core Solid iron, magnesium, silicon oxides Lower mantle – 1385 mi. thick Lower mantle cooler than outer core, so solid Upper mantle – 260 mi. thick Upper mantle mostly viscous nickel – like syrup Upper part of upper mantle is Aesthenosphere

9. © 2007, John Wiley and Sons, Inc. Aesthenosphere 25-105 mi. below surface Zones of molten rock heated by radioactive decay make up 10% of aesthenosphere These zones basis of plate tectonics, earthquakes, volcanoes, mtn building

10. © 2007, John Wiley and Sons, Inc. Lithosphere Uppermost layer of the Earth Extends from surface down into aesthenosphere (44 mi.) Upper part of lithosphere is crust, brittle exterior of Earth 5-25 mi. thick Mohorovocic Discontinuity (Moho) – boundary between crust and aesthenosphere

11. © 2007, John Wiley and Sons, Inc. Earth’s Outermost Layers Oceanic Crust – ~5 mi thick – mostly basalt - dense Continental Crust - ~25 mi thick – mostly granite – less dense