Plate Tectonics

Plate Tectonics

1. Section 1: Earth's Interior

   • The deeper you go, the higher pressure and temperature.
   • The Mantle
     • The mantle is the layer of hot rock between the crust an the outer core.
     • Asthenosphere
       • The asthenosphere is the soft layer of the mantle.
     • Lower Mantle
       • The lower mantle extends down to the core.
     • Lithosphere
       • The Lithoshere is the uppermost part of the mantle and crust.
   • Exploring Inside Earth
     • Evidence From Rock Samples
       • Geologists drill holes into Earth to find rock samples.
     • Evidence From Seismic Waves
       • Geologists send seismic waves Earth's interior to discover its structure.
   • The Crust
     • The crust is the layer of solid rock that forms the Earth's outer skin. -The crust is between 5 to 40 kilometers thick.-Under mountains the crust could be up to 70 kilometers thick

2. Section 2: Convection and the Mantle

   • Types of Heat Transfer
     • Radiation
       • Radiation is the transfer of energy through space -No direct contact; example:fire or sun
     • Convection
       • Convection is heat transfer by currents of fluid. Density is the measurement of how much mass a substance has.
     • Coduction
       • Conduction is the transfer of heat within materials that are touching. -Particles vibrate faster so as they touch they heat up.
   • Convection Currents
     • A convection current is the flow that transfers heat within a fluid. -Convection currents continue as long as heat is added.
   • Convection Currents in Earth
     • -In Earth's mantle large amounts of heat are transferred.

3. Section 3: Drifting Continents

   • Continental Drift
     • Evidence From Ancient Climate Zones
       • -Spitsbergen is currently covered in ice yet scientists found fossils from a tropical climate.These shows that Spitsbergen used to be near the equator. -Scratches in rocks show tha tSouth America used to be covered with glaciers.
     • Evidence From Fossils
       •  A fossil is any trace of an ancient organism that has been preserved in rock.
     • Evidence From Land Features
       • -Landforms, i.e. mountains, provide evidence of continental drift.
   • Wegner's Idea Rejected
     • HIs idea was rejected due to the fact that he could not provide a satisfactory explanation.

4. Section 4: Sea-Floor Spreading

   • Mid-Ocean Ridges
     • A mid-ocean ridge is an undersea mountain chain that is part of a long system of mountains that winds beneath the ocean. They curve an extend into all of Earth's oceans. Sonar is a device that bounces sound waves off underwater objects and then records the echoes.
   • What is Sea Floor Spreading
     • Sea floor spreading continually adds new material to the ocean floor. Quote: "In sea floor spreading, the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. As a result, the ocean floors move like conveyer belts, carrying the continents with them."
   • Evidence For Sea Floor Spreading
     • Evidence From Molten Material
       • Scientists found strange rocks formed when molten material hardens.
     • Evidence From Drilling Samples
       • Scientist have found out that the farther away the rocks got from the ridge the older they were.
     • Evidence From Magnetic Stripes
       • Scientists have found out that the magnetic poles have switched many times by looking at the magnetic stripes on the ocean floor.
   • Subduction at Trenches
     • The Process of Subducion
       • Subduction is the process in which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.
     • Subduction and Earth's Oceans
       • The Pacific Ocean is slowly shrinking due to subduction. While the Pacific Ocean is shrinking the Atlantic Ocean is expanding due to sea floor spreading and a few short trenches.

5. Pangaea

   • Pangea is the supercontinent that was formed about 300 million years ago. Then about 175 million years ago it started to break apart and form the world we know today. -Pangea was surrounded by a super ocean called Panthalassa 

6. Section 5: Theory of Plate Tectonics

   • How Plates Move
     • The theory of plate tectonics states that pieces of Earth's lithosphere in slow, constant motion, driven by convection currents in the mantle. It explains the formation, movement, and subduction of the plates. Geologists think that the convection currents in the mantle are strong enough to carry these heavy plates.
   • Plate Bounderies
     • Faults are breaks in Earth's crust where rocks have slipped past each other.
     • Spreading Boundaries
       • Spreading boundaries is when two plate move apart. (also called divergent boundaries) A rift valley is a deep valley that form along spreading boundaries.
     • Colliding Bounderies
       • A colliding boundary is when two plates come together, or collide. (also called a convergent boundary) Three Types: 1.Two plates made of oceanic crust meet at a trench, the denser plate sinks below the other. 2.Two plates, one oceanic the other continental, collide. Subduction occurs and the denser oceanic plate sinks beneath the continental plate. 3.Two continental plates collide but subduction does not occur. Instead they rise into great mountain ranges.
     • Sliding Bounderies
       • A sliding boundary is a place where two plates slip past each other.
     • Plate Motions Over Time
       • Movements of the plates have changed the face of the Earth many times. Geologists have proof that there were many supercontinents before Pangea.