Plate Tectonics Flashcards
Explain how geologists discovered the theory of Plate Tectonics?
Geologists discovered by the CONTINENTAL DRIFT HYPOTHESIS. Proposed by Alfred Wegner in 1915. He proposed PANGAEA and said that the continents separated slowly to where they are now.
Lithosphere vs Asthenosphere? Difference between continental and oceanic crust?
Describe the structure of the Earth’s crust and upper mantle?
Earth’s crust is made up of TWO crusts: the CONTINENTAL CRUST (what we are standing on) and the OCEANIC CRUST. The Upper Mantle is made up of materials known as LITHOSPHERE AND ANTHENOSPHERE. LITHOSPHERE is near CRUST AND UPPER MANTLE and is more RIGID/STRONG. The ATHENOSPHERE is part of UPPER MANTLE and is WEAK/DUCTILE.
How was the seafloor spreading discovered and how is it related to continental drift?
When ships tracked along the ocean floor they measured the magnetic field of the seafloor leading to its discovery. Other evidence for seafloor spreading was SEAFLOOR SEDIMENTS. Proof of seafloor spreading and continental drift was use of PALEOMAGNETISM which is a record of the Earth’s magnetic field in the past.
Describe the distribution of tectonic plates?
The DISTRIBUTION THEORY of plate tectonics is that MOUNTAINS are places that FORMER PLATE TECTONICS COLLIDED.
How are plate velocities and the spreading rate calculated?
We measure it between a RIDGE AXIS and LOCATION WITH OCEAN FLOOR OF CERTAIN AGE. PLATE VELOCITY is calculated by DISTANCE OF LOCATION TO RIDGE DIVIDED BY AGE OF SEAFLOOR LOCATION. SPREADING RATE is calculated by PLATE VELOCITY TIMES 2.
Understand what happens when plates meet - convergent, divergent and transform
boundaries. What are the geologic features at various geologic settings?
TRANSFORM boundaries are found at any part of the world. DIVERGENT boundary is found between ocean-ocean or continent-continent. CONVERGENT can be found ocean-ocean, ocean-continent, and continent-continent.
