OCB3034 Main Page

FIU Home

FIU Marine Biology Home

Dept. Biology Home

Frank Jochem Home

E-Mail

• Earth: built by distinct layers: inner core, outer core, mantle, crust; the crust is the thinnest layer
  
• Lithosphere: outer rigid „shell“ of Earth
• Asthenosphere: warmer, plastic (flowing) underlying layer of mantle
• Continents are „floating“ on plastic layers: Alfred Wegener‘s theory of continental drift (1915), proven in the late 1960‘s by deep-sea sediment cores
  
• Tectonic plates: Earth‘s surface is composed of several drifting plates, comprising both continents and sea floor
  
• Heat from Earth‘s interior causes convection cells within magma
• Mid-ocean ridges: hot magma breaks through lithosphere and „pushes“ lithosphere to both sides; plates move away from ridges
• Deep-sea trenches are subduction zones: two plates collide due to opposite drift directions, one plate dives underneath the other; the subducted plate material is melted into the magma again
  
• Ring of fire: plate borders can be seen by plotting earth quakes or vulcanic activity, which occur at plate boundaries
  
• Origin of oceans
  
• Origin of volcanic islands on top of hot spots
  
  
  
  

• Pangaea: the original Earth‘s land mass, surrounded by the ocean Panthalassa (the ancient precursor of the Pacific Ocean)
• Laurasia & Gondwanaland: evolved by the split-up of Pangaea ca. 200 million years agoLaurasia = today‘s Europe, Asia, and North America; Gondwanaland = today‘s Africa, South America, India, Australia, Antarctica
• Tethys: separated Laurasia and Gondwanaland; precursor of today‘s Mediterranean Sea
• Atlantic and Indian Oceans: new oceans created by the movement of continental plates, still continuously enlarging
  
  
  
  Whereas Alfred Wegener (1880-1930) tried to bring together today‘s land mass margins, the puzzel can be nicely solved by working with the 2000 m depth lines (Sir Edward Bullard, 1965).