Post on 15-Feb-2016
description
INTERNAL FORCES SHAPING THE EARTH
CH. 4.1
Earth’s Layers:• Core –
• Inner: solid metallic center of Earth • Outer: liquid metallic center of Earth
• Mantle – • soft layer of molten rock (Magma) floating on the core
• Crust – • thin layer of rock at the surface
• Volcanoes – • Openings in Earth's crust thru which molten lava, ash, & gases are ejected
• Magma – • Molten rock beneath the surface
• Lava – • Molten rock on the surface
• 1912: Alfred Wegener: • Suggested Continental Drift Theory after looking at map of world• Found fossils of extinct animals on different continents
• 1950s & 1960s: ocean floor was studied • Underwater mtns. ring the edges of continents • 1968:
• dfdf
• 1968: Theory of Plate Tectonics • Earth’s crust is divided into rigid plates that move slowly on the upper
mantle—set in motion by convectional heat from the core • Move in different directions• Over 12 plates
• Pangaea • When all of Earth’s continents were one (225 mill. yrs. Ago)
• Laurasia• Northern half of Pangaea
• Gondwanaland • Southern half of Pangaea
Plate Boundaries • Divergence:
• Spreading/pulling apart• Mid-Atlantic Ridge• Iceland / Surtsey• Video clip
• Convergence:• Continental plates crash into one another• Himalaya Mtns.
• Subduction:• Lesser oceanic plate is forced under dominant continental plate • Trenches (Mariana Trench)• Mountains (Japan, Andes Mtns., Cascade Mtns.) • Video clip
• Transform:• Plates move laterally passed one another • New Madrid, MO• San Andreas Fault
Type:
SOME Geologically-Active Places:• Ring of Fire:
• Geologically-active region around the perimeter of the Pacific Ocean• 75% (452) of world’s active & dormant volcanoes• 90% of world’s earthquakes
• Video clip
• Great Rift Valley:• Divergent plate boundary in E. Africa
• Mariana Trench:• Subduction plate boundary• Deepest part of the ocean
• Challenger Deep• >36,000 ft. deep• James Cameron (March 2012)
• ddf