Plate Tectonics

Plate Tectonics

1. Section 1: Earth's Interior

   • Exploring Inside Earth
     • Evidence from rock samples and seismic waves are used to build a picture of Earth's interior.
     • Evidence From Rock Samples
       • Scientists drill holes in earth to find evidence from rock samples.
     • Evidence From Seismic Waves
       • Scientists send waves into Earth's interior to discover it's structure.
   • Journey to the Center
     • The layers (crust, mantle, and core) vary greatly in size, composition, temperature, and pressure.
     • Pressure
       • Pressure: the result of force pressing on an area. The deeper you go, the stronger the pressure.
     • Temperature
       • The deeper inside you go, the higher the temperature. -40 meters= +1 degree Celcius
   • The Mantle
     • Mantle: A layer of hot rock between the crust and outer core. It's made up of rock that is very hot, but solid. Overall it is 3,000 kilometers thick.
     • Lithosphere
       • Lithosphere: The uppermost part of the mantle, and right below the crust.
     • Lower Mantle
       • below the asthenosphere it's solid and extends all the way down to the core.
     • Athenosphere
       • It's the soft layer of the mantle, and is bendable.
   • The Crust
     • A layer of solid rock with dry land and ocean land. It can be from 5-70 kilometers thick.
   • The Core
     • Made up mostly of the metals iron and nickel. In total, the inner core and outer core are 3,486 kilometers thick.
     • The Outer core and Inner Core
       • Outer Core: a layer of molten metal (liquid) that surrounds the inner core. Inner Core: a dense ball of solid metal made of iron and nickel.
     • The Core and Earth's magnetic Field
       • Scientists think that movements in the liquid outer core create Earth's magnetic field. The field affects the whole Earth.

2. Section 2: Convection In The Mantle

   • Types of Heat Transfer
     • When fluid is heated, the density decreases, and when cooled, the density increases.
     • Convection
       • Convection: Heat transfer by the movement of currents within a fluid. Density: a measure of how much mass there is in a volume of a substance. heated particles begin to flow and transfer heat from one fluid to another, by difference in temperature and density in a fluid.
     • Radiation
       • Radiation: Transfer of energy through space. Takes place with no direct contact between a heat source and an object. Ex: the sun and Earth.
     • Conduction
       • Conduction: Heat transfer within a material or between materials that are touching. Particles near the bottom vibrate faster as they are heated, and when they are bumped into each other, heat transfers.
   • Convection Currents
     • The flow that transfers heat within a fluid. The warm, less dense air moves upward and floats over the cold er air, and the cold air ids pulled downward by gravity, where it is heated again.
   • Convection Currents In Earth
     • The rocks in the lower mantle are hotter, and less dense. Solid mantle rock rises, and eventually cools, and sinks back down. This process takes millions of years.

3. Section 3: Drifting Continents

   • Continental Drift
     • Continental Drift: When the continents slowly moved over Earth's surface. The continents drifted together to form the supercontinent,Pangea, meaning "all lands".
     • Evidence From Land Features
       • Coal fields lined up on different continents, and Wegener pieced together the continents and it fit perfectly, so it was a super continent.
     • Evidence from Fossils
       • Fossil: any trace of a ancient organism that has been preserved in rock. Fossils were found on different continents that are now separated by oceans, bt they couldn't have survived the ocean trip.
     • Evidence From Ancient Climatic Zones
       • Glaciers were found on the coast of South Africa, near the equator, where it is warm.
   • Wegener's Hypothesis
     • His hypothesis was rejected, because it did;t explain the force of pushing and pulling along the continents, and it contradicted their ideas on how mountains form. I learned that mountains form when when continents collide, they crumple and fold.

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 the Earth's ocean floor. Sonar: a device that bounces sound waves off underwater objects and than records the echoes  of the sound waves.
   • What is Sea-Floor Spreading
     • Sea-floor spreading: the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added.
   • Subduction at Trenches
     • Deep-ocean trenches:under water canyons.
     • The Process of Subduction
       • Subduction: the process in which the ocean floor sinks beneath a deep-ocean trend and back into the mantle.
     • Subduction and Earth's Oceans
       • It changes the size and shape of the oceans, and renews the ocean floor about every 2 million years.
   • Evidence From Sea-Floor Spreading
     • Evidence From Molten Material
       • New material is indeed erupting along mid-ocean ridges.Rocks  from molten material hardening quickly under water were found along mid-ocean ranges.
     • Evidence From Magnetic Stripes
       • The magnetic poles reversed themselves 780,000 years ago. They found magnetic stripes that pointed north, which was the alternate of the ones that pointed south.
     • Evidence From Drilling Samples
       • The farther away from the ridge the rocks were, the older they were, and the ones in the center were always the youngest.

5. Section 5: The theory of Plate Tectonics

   • Cracks that break the lithosphere into separate sections called plates.
   • How Plates Move
     • Plate Tectonics: The theory states that pieces of Earth's lithosphere are in slow, constant motion, driven by convection currents in the mantle. Earthquakes, volcanoes, mountain ranges and deep-ocean trenches are caused by plates moving.
   • Plate Boundaries
     • Faults: breaks in Earth's crust where rocks have slipped passed each other. Plates move about 1-24 centimeters per years; the Northern American and Eurasian plates move about 2.5 centimeters per year.
     • Spreading Boundaries
       • Spreading Boundaries: the place where two plates move apart. Ridge Valley: a deep vally that forms along the spreading boundary.
     • Sliding Boundaries
       • Sliding Boundary: a place where two plates slip past each other, moving in opposite directions.
     • Plate Motions Over Time
       • Pangea itself formed 260 million years ago. 225 million years ago, Pangea began to break apart.
     • Colliding Boundaries
       • Colliding Boundaries: the place where two plates come together, or collide. #1: two plates made up of oceanic crust meet at a trench. #2: an oceanic plate collides with a continental plate. #3: two plates carrying continental crust, collide and squeeze the crust into mighty mountain ranges.