Plate Tectonics Goal 2.1
Lesson 1 Plate Tectonics: An Overview
Think About It Look at the map below. Which two continents look like they d fit together?
Focus Question How do Earth s tectonic plates cause volcanoes to form? earthquakes to occur? Earth s surface features to form?
1. What is the theory of continental drift? Continental Drift The continents had once been joined as a single landmass that split (drifted) apart. http://rosalieee.files.wordpress.com/2009/01/pangea-continental-drift.jpg?w=596&h=489
Continental Drift 2. What was Pangaea? the ancient super- continent http://pubs.usgs.gov/gip/dynamic/historical.html
3. Evidence Supporting Continental Drift a. the puzzle-like fit continents on either side of the Atlantic Ocean http://earthscience.wordpress.com/2007/04/13/day-143-continental-drift-puzzle/
Evidence Supporting Continental Drift Rocks and Fossils b. Rock formations & fossils on both sides of the Atlantic Ocean match. http://choralemaacher.lu/continental-drift-evidence-mountains
Evidence Supporting Continental Drift Fossils http://abyss.uoregon.edu/~js/images/fossil_break.gif
Evidence Supporting Continental c. Climate changes... Coal deposits in Antarctica (warmer and farther north) Glacial erosion in India, Africa, and Australia (colder and farther south) Drift Climate http://blue.utb.edu/paullgj/physci1417/lectures/gondwanaland_glaciations.jpg
Seafloor Spreading 1. The theory of seafloor spreading states new ocean crust is formed at the ridges and destroyed at trenches.
Seafloor Spreading http://higheredbcs.wiley.com/legacy/college/levin/0471697435/chap_tut/images/nw0125-nn.jpg
How we know what s down there! https://directory.eoportal.org/web/eoportal/satellite-missions/t/topex-poseidon http://marinesciencetoday.com/2009/05/06/new-antarctic-sonar-images-reveal-clues-to-sea-level-rise/
2. Preview of the Ocean Floor a. An ocean ridge is vast, underwater mountain range the longest on Earth! b. A deep sea trench is narrow, elongated depression in the ocean floor - deepest part of the ocean 11 km deep! See next slide
The Ocean Floor
Evidence for Seafloor Spreading a. Ocean rocks and sediments are younger at the midocean ridges.
Evidence for Seafloor Spreading b. Magnetism Basalt provides an accurate record of ancient paleomagnetism. i. Earth has had a series of magnetic reversals or changes in its magnetic field. ii. These are recorded in the ocean floor. The magnetic pattern on either side of a midocean ridge is a mirror image. DRAW ME!!
DRAW ME!!
http://www.uwsp.edu/geo/faculty/ritter/glossary/s_u/sea_flr_spread.html How Seafloor Spreading Occurs Step 1: Magma rises and fills the gap. Step 2: Magma solidifies to form new crust. Step 3: New crust is continually made and pushes the older crust to the outer edges of the ocean. See next slides
A Bigger View!
http://www.moorlandschool.co.uk/earth/tectonic.htm
The Theory of Plate Tectonics 1. The theory of plate tectonics Earth s rigid crust and upper mantle is broken into large plates. http://geology1a-1.wikispaces.com/plate+boundary+images+and+captions
2. Plate Boundaries (Add to Lesson 1.) a. Divergent plates separate b. Convergent plates are moving toward each other c. Transform slide horizontally past each other Click here to investigate the boundaries http://geology.com/plate-tectonics.shtml
The Plates Australian plate - pink or lighter orange, Nazca & Scotia plates lighter blue
Lesson 2 Plate Tectonics Divergent Boundaries
Think About It Why do some parts of Earth have volcanoes and earthquakes and others don t?
Focus Question What geologic activity occurs at a divergent plate boundary?
Plate Boundaries: The Big Pic http://geology1a-1.wikispaces.com/plate+boundary+images+and+captions
Divergent Boundary 1. A divergent boundary is one where the plates are separating or moving apart.
2. Geological Processes a. High heat flow magma pushes up into the rift valley.
2. Geological Processes b. Volcanoes formed by the magma rising at the rift valley
2. Geological Processes c. Earthquakes caused by the magma breaking rocks on its way to the surface
Divergent Boundaries 3. Divergent boundaries form rift valleys where magma rises, solidifies, & pushes plates apart. DRAW ME!!
Divergent Boundary 4. The underwater mountain range formed at divergent boundaries in every ocean is The midocean ridge
5. Examples - Iceland
East Africa Rift Valley http://geology.com/articles/east-africa-rift.shtml
The Midocean Ridges http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/p_midoceanridges.html
Lesson 3 Convergent Boundaries
Think About It Where do many of our most devastating earthquakes occur?
Focus Question What geologic activity occurs at a convergent plate boundary?
Plate Boundaries: The Big Pic http://geology1a-1.wikispaces.com/plate+boundary+images+and+captions
Convergent Plate Boundaries There are 3 types of convergent plate boundaries depending on their locations Ocean/continental Ocean/ocean Continental/continental We will look at each type separately
Convergent Boundaries: Ocean/Ocean 1. Subduction is the process of one plate going under another. The process of subduction creates a deep-sea trench. 2. The underground edge of the subducting plate melts because it is pulled deep into Earth s crust. Melted crust rises to form a volcanic island arc.
Effects of Plate Snapping 3. Two devastating effects of a plate snapping back are a. Earthquakes b. Tsunamis See clips http://tsunami2004videoarchive.com/tsunami_video_key_video.htm http://d3sdoylwcs36el.cloudfront.net/map_of_thye_areas_hit.gif
Convergent Boundaries: Ocean/Ocean 4. The type of fault found at this boundary is reverse http://www.artinaid.com/wp-content/uploads/2013/04/reversefault.gif
Let s Draw! Convergent Boundaries: Ocean/Ocean DRAW ME!! http://www.indiana.edu/~geol116/week7/conver.jpg
Convergent Boundaries: Ocean/Ocean 5. Examples of this are a. Mariana Islands b. Japan c. Indonesia
Convergent Boundaries: Ocean/Ocean Another Example The Japanese Islands
Convergent Boundaries: Ocean/Continental 1. The oceanic plate subducts under the continental plate. (It is denser.) 2. A volcanic mountain range forms on land above the subduction zone. 3. Examples include Andes Mountains (S. America) and the Cascade Mountains in N. America)
Convergent Boundaries: Ocean/Continental The Andes of S. America http://www.worldtravelattractions.com/cascades-cascade-range/ http://www.100destinos.com/imagenes/los-andes-chile.jpg The Cascades of N. America
Let s Draw! Convergent Boundaries: Ocean/Continental DRAW ME!! http://elearning.stkc.go.th/lms/html/earth_science/locanada4/403/images/3_1.jpg
Convergent Boundaries: Continental/Continental 1. A folded mountain range is formed when two continental plates collide. (They are both too thick to go under.) 2. Examples include the Himalaya Mountains and the European Alps. DRAW ME!! Let s Draw!
The Appalachian Mountains and the Piedmont They started as a continental fragment and a volcanic island arc about 700 600 mybp. The continental fragment moved west & became the Blue Ridge Province. (500-400 mybp) The island arc moved west & became the Piedmont Province. (400-300 mybp) The folded Valley and Ridge (c/c) formed when the N. American and African plates collided. (300-260 mybp)
Lesson 4 Transform Boundaries
Transform Boundaries 1. Transform refers to moving across. 2. At transform boundaries, crust is only deformed or fractured. 3. Volcanoes and mountains don t form here because there is NO vertical movement of the plates. 4. The type of faults formed here are called strike-slip faults 5. Transform boundaries are characterized by shallow earthquakes. DRAW ME!!
Haiti, 1/2010 (7) 6. Examples include: San Andreas Fault in California Haiti
Plate Boundary Activity http://geology.com/plate-tectonics.shtml
Causes of Plate Movements 1. Large-scale motion in the mantle drives the movement of the plates. http://www.nakedscience.org/mrg/plate%20tectonics%20lecture%202_files/image018.jpg
Causes of Plate Movements 2. Definitions a.mantle layer of Earth beneath the crust b.asthenosphere partially molten layer of the mantle
Causes of Plate Movements Definitions c. Convection transfer of thermal energy by the movement of heated matter d. Convection current pattern of motion produced by warmer matter moving up and cooler matter sinking http://library.thinkquest.org/c003124/images/convect.jpg
Causes of Plate Movements 3. The tectonic plates move by a. The rising part of the convection current spreads out as it reaches the upper mantle which lifts and splits the lithosphere at divergent plate boundaries. b. The downward part of the convection current creates a sinking force that pulls tectonic plates downward at convergent boundaries.
Causes of Plate Movements 3. The tectonic plates move by c. Ridge push - the force created by the weight of the uplifted ridge which pushes an oceanic plate towards a trench. (at a subduction zone) d. Slab pull - process in which the weight of the subducting plate helps pull the trailing lithosphere into the subduction zone.
DRAW ME!! Causes of Plate Movements
Causes of Plate Movements http://www.fas.org/irp/imint/docs/rst/sect2/sect2_1b.html