Plate Tectonics

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Chapter 15

• Plate Tectonics
• theory explaining movements of Earths crust
• Evidence of plate movement (Pangaea)
• 1. similar fossils on separated continents
• 2. Folded mountains of same age type
• on edges of separated continents
• 3. Glacial deposits with similar flow direction
  
• rock, some in warm climate
• 4. Salt deposits in MI UT
• 5. Coal deposits in Antarctica
• 6. Coral limestone deposits in N. US

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• B. 7 Major Plates (P.556)
• N. American S. American
• Eurasian African
• Indoaustralian Pacific
• Antarctic
• -plates move in different directions due to
  convection currents in Mantle
• -some push together, some pull apart

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• C. Plate Boundaries
• 1. Divergent/Constructive Boundary
• ocean plate/ocean plate Movement plates move
  apart,
• magma flows out
• Resulting Land Feature
• ocean floor spreading
• Examples Mid-Atlantic Ridge
• African Rift Valley (Red Sea)
• Gulf of California

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• 2. Convergent/Destructive Boundary
• ocean plate/continental plate Movement plates
  move together,
• ocean goes under continent
• Resulting Land Feature
• Volcanic Mountains Trenches
• Examples Andes Mountains
• Cascade Mountains
• Aleutian Trench

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• 3. Convergent/Destructive Boundary
• ocean plate/ocean plate Movement plates move
  together,
• one goes under other
• Resulting Land Feature
• Island Arcs with Volcanoes
• Examples Philippine Islands
• Japanese Islands

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• 4. Convergent/Constructive Boundary
• continental plate/continental plate Movement
  plates move together,
• fold up buckle
• Resulting Land Feature
• Folded Mountains
• Examples Himalayan Mountains
• Ural Mountains
• Alps

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• D. Earthquakes
• can happen along plate boundaries
• or faults (fractures in crust)
• focus place where crust moved
• epicenter point on surface above focus
• Richter Scale
• -measures earthquake intensity
• -each 10X increase in vibration energy

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• 3 Types of Earthquake Waves
• 1. P waves ( primary waves)
• -longitudinal, compression waves
• -fastest speed
• 2. S waves (secondary waves)
• -transverse waves
• -move slower
• -will not travel through liquids
• (outer core is liquid)
• 3. L waves (love waves)
• -surface waves
• -move slowest

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• E. Volcanoes
• -occur along plate boundaries
• -must have at least one ocean plate
• 3 Types of Volcanoes
• 1. Cinder Cone Volcanoes
• -explosive eruptions
• -steep sides
• -narrow base

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• 2. Shield Volcanoes
• -quiet lava flows
• -gentle slope
• -dome shaped
• 3. Composite Volcanoes
• -explosion, then lava flow
• -layers of rock/ash lava

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• II. Geologic Time
• A. Methods of Dating Rock Layers
• 1. Relative Age
• -oldest layers on bottom,
• youngest on top
• 2. Absolute Age
• -uses radioactive half-lives
• -index fossils

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• B. Time Divisions
• -based on biological extinctions
• 1. Pre-Cambrian Era (oldest)
• Fossils present
• marine invertebrates
• bacteria
• algae
• 2. Paleozoic Era Age of Fish
• Fossils present
• fish amphibians
• trilobites
• coal deposits (ferns)

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• 3. Mesozoic Era Age of Reptiles
• Fossils present
• dinosaurs birds
• flowering plants
• 4. Cenozoic Era Age of Mammals
• (includes present)

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• Quiz Next Week
• Describe the 4 types of Plate Boundaries
• Given type of plate (e.g. ocean continent)
• -convergent or divergent?
• -moving together or moving apart?
• -constructive or destructive?
• -resulting land feature
• -specific example