Oceanography Plate tectonics
• Centrifugal forces
• Inertia and tidal drag from the sun and the moon
• Puzzle pieces fit together
• PROS: Mountain ranges and fossils would fit if all continents were put together.
• No trails
• The crust and mountains were supported mechanically
Theory of plate tectonics
• Progress was made in understanding that earth was density stratified and that the
• Body waves: Traveled through the interior of the earth
• P waves
• S waves They travel at different speeds.
• P waves show up first then the s waves appear
• P: compression waves travel twice as fast through the earth
• S: side to side
• P waves can penetrate through the liquid outer core, but are bent in transit.
• S waves cannot travel through liquid, creating a large shadow zone between 103 and
180 degrees from an earthquakes source.
Earth Structure 2 Perspectives.
• Chemical Composition
• Looks at the chemical composition of the earth
• Results from the process of young earth and subsequent density stratification
• Physical states
Crust: uppermost layer
Mantle: Layer beneath crust Most of earth’s mass and volume
Core: inner and outer core
Crust in two components
~ Oceanic crust: basalt
~Continental crust: Granite
Mantle consists of mainly silicon and oxygen with some iron and magenesium
Core Consists of iron and nickel
Earth’s interior layer based on physical
• Lithosphere • Lithos: Rocks
• Earth’s cool, rigid, outer layer.
• Asthenosphere Asthenus (weak)
• Is the hot, partially melted layer, slow
• Lower mantle extends all the way to the core
• Hotter than the asthenospher