1	Today Earth’s Internal Structure Plate Tectonics
2	Earth’s Internal Structure
3	More About Tectonic Plates Two ways to describe Earth’s Interior Crust Mantle Outer Core Inner Core Lithosphere Asthenosphere Mesosphere
4	Earth’s Internal Structure Description of Composition Inner Core Iron & Nickel Solid Outer Core Iron & Nickel Liquid Mantle Dense rock material “Plastic” solid Crust Oceanic or Continental Rock
5	Crust Rock Thin, outermost layer of earth Less dense than other parts of earth Continental Crust ~40 km thick Less dense than ocean crust Light-colored rocks Ocean Crust ~8 km thick More dense than continental crust Dark colored rocks
6	Fun Facts If earth was shrunk down to the size of a Ping Pong ball Its surface would be smoother than that of a Ping Pong ball. Its crust would be thinner than that of a Ping Pong ball.
7	The Lithosphere Contains crust and mantle Thickest under continents up to 250 km Thinnest under oceans ~100 km Includes Tectonic Plates Crust and Mantle
8	The Asthenosphere Extends from bottom of lithosphere to ~650 km Top is partly melted 1-5% Behaves like thick liquid Allows Lithospheric Plates to move Within mantle
9	Structure of the Earth Description of Physical Properties Lithosphere “Rock sphere” Rigid outer shell of earth Includes some crust and some mantle Asthenosphere “Weak sphere” Within the mantle Rock material at high pressure and temperature Flows like thick liquid
10	Tectonic Plates
11	Ridges, Trenches & Transform Boundaries
12	Quicktime Movie
13	Three Types of Plate Boundaries Divergent Plates moving apart Convergent Plates moving together Transform Plates sliding past each other
14	Three Types of Plate Boundaries Divergent Convergent Transform
15	Divergent Boundaries Mostly located at mid-ocean ridges Sea-floor spreading Creation of ocean basins “Rift Valleys” Bounded by undersea volcanic “mountain chains”
16	East African Rift Valleys Initial stages of continental breakup Volcanic Mts Kilimanjaro Mt Kenya Rift basins Red Sea
17	Other Ancient Rift Valleys For other cool maps check out http://www.lib.utexas.edu/Libs/PCL/Map_collection/americas.html http://www.research.digital.com/SRC/personal/birrell/reliefMaps/
18	Three Types of Plate Boundaries Divergent Convergent Transform
19	Convergent Boundaries: Three Combinations Ocean Crust – Continental Crust Ocean Crust – Ocean Crust Continental Crust – Continental Crust
20	Oceanic-Continental Plate Collisions Denser ocean crust sinks Subduction zone Deep-sea trench Oceanic plate melts – 100-150 km deep Volcanic arcs above melting Sierra Nevada Mountains, Andes
21	Snowcapped Volcanoes of Southern Peru
22	See Spectacular Images From Space
23	Oceanic-Oceanic Plate Collisions One plate sinks (usually the older & colder) Subduction zone Deep-sea trench Volcanoes in ocean floor Japan, Philippines, Lesser Antiles (Caribbean), Aleutian Islands
24	Western Aleutian Islands
25	Continental -Continental Plate Collisions No subduction zone Crust buckles and fractures Usually preceded by oceanic subduction Himalayas, Appalachians, Alps
26	The Himalaya
27	Everest From Space
28	Collision Zones The Himalaya
29	Three Types of Plate Boundaries Divergent Convergent Transform
30	Transform Boundaries Plates Slide Past One Another Laterally Mid Ocean Ridges connected by Transform Boundaries Crust not created or destroyed
31	Transform Boundaries
32	Transform Boundary San Andreas Fault
33	San Andreas Fault in the Bay Area
34	Transform Margin San Andreas Fault, CA
35	East African Rift Valleys Initial stages of continental breakup Volcanic Mts Kilimanjaro Mt Kenya Rift basins Red Sea
36	Red Sea Rift
37	More Evidence of PT Earthquakes Earthquakes tend to be associated with plate boundaries Deep earthquakes at subduction zones
38	Earthquakes at Subduction Zones