Plate Tectonics

Plate Tectonics

1. Section 1: Earth's Enterior

   • Exploring Inside Earth
     • scientists drill holes for samples they sen waves into Earth's interior to discover its structer
   • Journey to the Center
     • the deeper you go the higher the temperature the deeper you go the stronger the pressure PRESSURE: result of force pressing on an area
   • The Mantle
     • Lithoshere
       • LITHOSPHERE:uppermost part of the mantle and the crust
     • Lower Mantle
       • solid and extends down to the Earth's core
     • Athenosphere
       • ASTHENOSPHERE: soft layer of mantle below the lithosphere  bendable but still a solid
   • The Crust
     • CRUST: the layer of rock tat forms Earth's outer skin. Crust is between 5 to 40 km thick note: under mountains is 70 km thick
   • The Core
     • Outer Core and Inner Core
       • OUTER CORE: a layer of molten metal that surrounds the inner core INNER CORE: a dense ball of solid metal both parts of the core are made of iron and nickel
     • The Core and Earth's Magnetic Field
       • If you put iron fillings around the Earth, it would have the same reaction if you did it with a magnet bar

2. Section 2: Convection and the Mantle

   • Convection Currents
     • CONVECTION CURRENTS: the flow that transfers heat within a fluid
   • Convection Currents in Earth
     • heat from the core and the mantle create heat in the mantle
   • Types of Heat Transfer
     • RADIATION: the transfer of energy through space CONVECTION: heat transfer by the movements of currents within a liquid CONDUCTION: transfering heat through a material or between materials that are touching

3. Section 3: Drifting Continents

   • Continental Drift
     • CONTINENTAL DRIFT: when continents slowly moved over the Earth's surface PANGAEA: continents drifted together to create a "supercontinent" Wegener's hypthesis was that before all the continents were together, then they slowly drifted apart
   • Evidence from Land Features
     • when Wegener pieced the continents together, they fit together perfectly so that proves they were once one continent
   • Evidence from Fossils
     • FOSSIL: any trace of and ancient organism that has been preserved in a rock wegener also used fossils to support his hypothisis. He found that the same species were spread around the whole world
   • Evidence from Ancient Climatic Zones
     • Wegener also used climate to prove his point. He found that Spitsbergen had once been warm and that South Africa had once been cold
   • Wegener's Hypothisis Rejected
     • Unfortunatly, Wegener could not provide the right explanation of the force of pushing and pulling along the continents It was in the 1900's when geologists finally accepted Wegener's hypothesis

4. Section 4: Sea-Floor Spreading

   • Mid-ocean Ridges
     • MID OCEAN RIDGE: an undersea mountain chain that is part of a long system of mountains that winds beneath Earth's oceans SONAR: a device that bounces sound waves off underwater objects and then records the echoes of these sound waves
   • What is Sea-Floor Spreading
     • SEA FLOOR SPREADING: continually adds new material to the ocean floor
   • Evidence for Sea-Floor Spreading
     • Evidence that support sea-floor spreading: eruptions of molten material , magnetic stripes in the rock of the ocean floor, and the ages of the rocks.
   • Evidence from Magnetic Stripes
     • scientists found that the rock on the ocean floor make a magnetic pattern of stripes. These stripes hold a " record" of the Earth's magnetic field
   • Evidence from Molten Material
     • when scientist went in a submarine called "Alvin" they found rocks that showed that molten material has erupted again and again along the mid-ocean ridges
   • Subduction at Trenches
     • DEEP OCEAN TRENCHES: the ocean floor sinks beneath deep underwater canyons a process taking millions of years , part of the ocean floor sinks back into the mantle at deep-ocean trenches
   • Evidence from Drilling Samples
     • the Glomar Challenger used pipes to collect rock samples from the ocean floor. Scientists found that the farther away rocks were from the ridges the older they were. The ones in the middle were the youngest ones. This shows that sea floor spreading took place
   • The Process of Subduction
     • SUBDUCTION: the process by which the ocean floor sinks beneath a deep ocean trench and back into the mantle
   • Subduction and Earth's Oceans
     • The Pacific Ocean is shrinking because it has many deep ocean trenches around its edges. Subduction occurs through these edges before new crusts can be added The Atlantic Ocean is expanding because it has only a few shot trenches. So most of the spreading ocean floor has nowhere to go

5. Section 5: The Theory of Plate Tectonics

   • How Plates Move
     • PLATE TECTONICS: the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle. The theory of plate tectonics explains the formation, movement, and subduction of  Earth's plates.
   • Plate Boundaries
     • FAULTS: breaks in Earth's crust where rocks have slipped past each other. 3 kinds of plate boundaries: spreading boundaries, colliding boundaries, and sliding boundaries. 
   • Spreading Boundaries
     • SPREADING BOUNDARY: the place where two plates move apart. Occurs in the mid ocean ridge where sea floor spreading occurs. Also can happen on landRIFT VALLEY: a deep valley that forms along the spreading boundary.
   • Colliding Boundaries
     • COLLIDING BOUNDARIES: the place where two plates come together, or collide. Can also be called convergent boundary. 1st type of collision: 2 plates made up of oceanic crust meet a a trench. 2nd type of collision: an oceanic plate collides with a continental plate. 3rd type of collision: 2 plates carrying continental crust collide, but subduction does not take place
   • Sliding Boundaries
     • SLIDING BOUNDARY: a place where two plates slip past each other, moving opposite directions.  Can also be called transform boundaries
   • Plate Motions Over Time
     • Pangaea about 300 million years ago, was a supercontinent. After millions of years the continents separated until it looked like what Earth looks like today.