Plate Tectonics

Plate Tectonics

1. Section 1: Earth's Interior

   • The deeper you go in the more the pressure
   • Exploring inside earth
     • geoligists use evidence to build a picture of earth 
     • Rock Samples
       • Drills bring up rock samples from inside of earth. Scientiscts often drill about 12 km into earth
       • Forces from inside Earth often blast rock more than 100 km below to the surface of the Earth
     • Seismic waves
       • Geologists use seismic waves to study Earth
       • They study seismic waves and how they travel threw Earth
       • When earthquakes occur they produce these waves 
       • The speed of these waves and the path reveal the structure of earth
   • The Crust
     • The crust is a layer of rock that fors earth's outer skin It is a solid layer of rock that includes both dry land and the ocean floorf
     • It is between 5-40 m thick but it can be up to 70 km thick beneath mountains  
     • The crust under the ocean is called the oceanic crust and the crust that forms continents is called continental crust 
   • The Mantle
     • The mantle is a layer of hot rock  The mantle is solid and is over 3,000 km thick
     • It is about 40 km beneath the surface
     • It is between the crust and core it has 3 layers
     • Lithosphere
       • The uppermost part of the mantleand the crust form a rigid layer called the lithosphere The lithophere is about 100 km thick
     • Asthenosphere
       • The lithosphere is just below the mantle  It is very weak, asthenes means weak in greek This layer is is very soft but it is also hot and always under increasing pressure 
     • Lower Mantle
       • This layer is beneath the asthenosphere
       • The mantle is solid
       • It extends all the way to the core 
   • Journey to the center
     • There are 3 main  layershe Earth of t 
     • Temperature
       • At 20 m down the rocks gets hotter
       • After that every 140 m you go it rises 1 C
       • Plate Tectonics
     • Pressure
       • The deeper you go the more the pressure
       • It is just like a swimming pool
       • Because of the weight of rock the deeper you go the more the pressure

2. Section 2: Convection and Mantle

   • Types of heat transfer
     • Heat moves from a hot substance to a cold substance
     • Radiation
       • The transfer of energy through space is called radiation
       • Sunlight that warms earth is radiation
     • Conduction
       • Heat transfer within a material or between materials that are touching is called heat transfer.
     • Convection
       • Heat can also be transferred by the movement between fluids LIQUID AND GAS
   • Convection Currents
     • A convection current is the flow that tranfers heat within a fluid 
     • They continue as long as heat is added
   • Convection Currents in Earth
     • Heat from the core and the mantle causes convection currents in the mantle.
     • As a result solid mantle rock rises slowly from the bottom of the mantle towards the top.

3. Section 3: Drifting Continents

   • The continents of Europe, Asia and Africa were known to mapmakers.
   • Continental Drift
     • Wegener's hypothesis was that all the continents were once joined together in a single landmass and have drifted apart
     • Wegener's idea that the continents slowly moved over Earth's surface became known as continental drift.
     • Pangaea means all lands according to Wegener's.  It existed 300 million years ago
     • Land Features
       • Mountains and other features on the continents provided evidence for Continental drift
     • Fossils
       • A fossil is any trace of an ancient organism that has been preserved in rock
       • Wegener also used fossils to support his argument for continental drift
     • Ancient Climatic Zones
       • Wegener used evidence of past climates to support his hypothesis
       • He found his evidence by studying fossils and rocks
   • Wegener's Hypothesis Rejected
     • Wegener could not provide a satisfactory explanation for the force that pushes or pulls the continents

4. Section 4: Sea-Floor Spreading

   • Mid-Ocean Ridges
     • A mid-ocean ridge is an undersea mountain range that is part of a long system of mountains that winds beneath earth's oceans
   • What is Sea-Floor Spreading?
     • In sea-floor spreading, the sea-floor spreads apart from both sides of a mid-ocean ridge as a new crust is added.  As a result, the ocean floor move like conveyor belts carrying the continents along with them.
   • Evidence for Sea-Floor Spreading
     • Molten Material
       • Molten material only shows when rocks erupt again and again along the mid-ocean ridges
     • Magnetic Stripes
       • Patterns in the rock of the ocean floor supports sea-floor spreading
     • Drilling Samples
       • Rock samples can be obtained by drilling into the ocean floor.  
   • Subduction at Trenches
     • Process of Subduction
       • The process by which the ocean floor sinks beneath a deep ocean trench and back into the mantle is called subduction
     • Subduction & Earth's Oceans
       • Together subduction and sea-floor spreading changes the shape and size of the ocean

5. Section 5:Theory of Plate Tectonics

   • How Plates Move
     • The theory of plate tectonics explains the formation ,movement  and subduction of earth's plates  
   • Plate Boundries
     • There are 3 different types of plate boundries
     • Colliding Boundries
       • The place were 2 plates collide
     • Sliding boundries
       • Two plates slip past each other
     • Spreading boundries
       • Where 2 movies move apart
     • Plate motions
       • The movements of earth's place move over time Pangaea formed 260 million years ag