Earth's Internal Structure

• Earth's internal structure -- 1
• Earth's internal structure -- 2
• Earth's internal structure -- 3
• Isostatic equilibrium 1 -- differences in crustal elevation due to density differences
• Isostatic equilibrium 2 -- differences in crustal elevation due to differences in crust thickness
• Isostatic uplift and subsidence caused by erosion and deposition
• Cross-section of U.S. crust -- showing greater crustal thickness beneatgh mountain ranges

Plate Tectonics

• Earth's tectonic plates
• Plate boundaries -- map shows plate boundary types and rates of movement
• Rates of plate movement
• Rates of plate motion
• Convergent and divergent plate margins
• Divergent plate boundary
• Divergent plate boundary -- origin of ocean basin by continental rifting
• Convergent plate boundary --subduction zone
• Convergent plate boundary -- oceanic-to-oceanic -- subduction zone and volcanic arc
• Convergent plate boundary -- oceanic-to-continental -- subduction zone and volcanic arc
• Convergent plate boundary -- continent-to-continent -- fold-mountain belt
• Transform plate boundaries -- transform fault
• Transform plate boundaries -- three types of transform boundary layouts
• Hotspots -- rising plumes of magma from deep in the mantle stay fixed while continents and sea floor shift over them
• Hotspots and rates of plate motion
• Convection cells in the Earth -- possible mechanism of plate motion
• Possible mechanisms of plate motion -- slab-pull and ridge-push
• Possible mechanisms of plate motion -- ridge-push, plate sliding, slab-pull

Geomagnetism and Magnetic Evidence for Sea-Floor Spreading

• The Earth's magnetic field
• Inclination of the Earth's magnetic field
• Declination of the Earth's magnetic field
• Remnant magnetism in volcanic rocks -- the orientation of Earth's magnetic field is recorded in iron-bearing minerals in a lava as it cools through its Curie point
• Magnetic signature of sea- floor spreading -- lavas formed at the mid-oceanic ridges record the orientation of the earth's magnetic field (normal or reversed) at the time of their formation
• Sequence of formation of magnetized lavas at mid-oceanic ridge
  • normal
  • reversed
  • normal again

 Other Evidence for Continental Drift and Sea-floor Spreading

• Evidence for continental drift 1 -- fit of continents
• Evidence for continental drift 2 -- distribution of dinosaurs
• Evidence for continental drift 3a -- Present-day distribution of late Paleozoic glacial deposits
• Evidence for continental drift 3b -- Reconstructed original distribution of late Paleozoic glacial deposits
• Age of the ocean floor -- Sea floor is youngest near the mid-oceanic ridges and gets older as we approach the trenches
• Hawaiian hotspot -- age of islands formed over hotspot increases and heights decrease westward as sea floor moves away from hotspot, cools, and sinks

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