Plate Tectonics

Plate Tectonic Vocabulary Continental drift Continental Crust Convection Convection Current Convergent Boundary Divergent Boundary Mid-Ocean Ridge Ocean Trench Pangaea Plate Tectonics Seafloor Spreading Subduction Zone Mid-Atlantic Ridge

Crust a. What are the two types of crust? b. Each type of crust is composed of what kind of rock? c. Which type of crust is denser?

Shorelines are not true boundaries: 1.Continental margin – where the ocean water covers the continental crust 2.Deep ocean basin- where the ocean water covers oceanic crust Oceanic crust Continental crust Oceanic basin waterContinental margin The ocean water may cover miles of the continental crust

Earth’s Tectonic Plates dpc.ucar.edu

The crust is broken into separate plates. How many plates are there? T or F Plates are stationary. Crust

Convection currents produced in the mantle cause the plates to move. As the plates move, everything on them moves along with them. Examples: *The North American plate moves west at a rate of 4 cm per year (1.6 in./yr) *The Pacific Ocean plate moves northward at the same rate. Plate Movement

PLATE TECTONICS The continental & oceanic plates on the earth’s surface are constantly moving. Many geologists believe that at one time all landmasses were together: supercontinent. Also called?

Pangaea

Alfred Wegener: He was a leading scientist in providing evidence that continents were moving. CONTINENTAL DRIFT THEORY: *Continents are drifting or moving. *Break-up of Pangaea occurred around 240 million yrs ago * Over time continents broke up into smaller pieces and have drifted to their current location *The continents are currently still moving uni-graz.at

Alfred Wegener: Continental Drift Evidence Evidence: 1. Similarities in coastlines 2. Similarities in fossil records 3. Similarities in rock

Continental Drift: Evidence 180 million years ago, Pangaea began to break up into separate continents. Provided evidence of ancient animal and plant remains from South America, Africa, India, and Australia that were very similar.

What problem or concern do you think other geologist had with Wegner’s theory? Could not provide direct evidence that the continents were moving. Wegener’s Continental Drift Theory

Where?: Under the Atlantic Ocean What? Mountain Range –Mid Atlantic Ridge the ridge looks like a mountain with a valley running down the center Who? Harry Hess Continental Drift Theory: Conclusive Evidence velikovsky.info

Aerial picture of the Mid-Atlantic Ridge

–Studied rock data from the Mid Atlantic Ridge –Found in the center of the ridge is a crack or rift. –Magma would flow up through this rift Harry Hess’ Important Observations

Harry Hess Conclusion: –The ocean floor was moving away from the ridge on both sides. –As it moved away, it was replaced by rising magma that cooled and solidified into new rock. – He called this process: Sea Floor Spreading

Sea Floor Spreading Thingvellir, the spreading zone in Iceland between the North American (left side) and Eurasian (right side) tectonic plates. January 2003.

Bell Ringer: Plate Tectonics 1. What layer of the earth is the plates located? 2.What indirect evidence did Wegener have to hypothesize his continental drift theory? 3.What direct evidence did Hess have to conclude from his research seafloor spreading? 4. From the article “Plate Tectonics: Earth’s Lucky Geology” identify three interesting facts from the article about plate tectonics.

Hess’ Later Observations and Conclusions –Continued to support sea floor spreading. – Evidence by further studying the structure, properties, and age of the rock around the Mid- Atlantic ridge.

Scientific Evidence is Dynamic Scientific evidence presented to the public is only established after years of sound research in the hands of many scientists. Despite this truth, scientists continue to test these facts as technology advances. Homework: Read and annotate the article “ UCLA scientist discovers plate tectonics on Mars”. Explain with three supporting facts from this article why the statement above is necessary for science to remain beneficial to humanity.

Plate Tectonics Homework due Wednesday: Annotate article and answer question related to article. Complete sea floor spreading questions. Complete questions from plate tectonic worksheet. Continue to record seismic activity. Quiz: Wednesday Test : Friday

Plate Boundaries Plate boundaries are where two plates meet. What type of plates can meet? There are 3 types of plate boundaries: 1. divergent boundaries 2. convergent boundaries 3. transform boundaries

Divergent Boundaries What are divergent boundaries?

Divergent Boundaries Iceland is above a divergent boundary. The North American Plate & the Eurasian Plate

Thingvellier,Iceland

Divergent Boundaries Mid-Atlantic Ridge: Extends from the Arctic Ocean to beyond the southern tip of Africa & moves 2.5cm per year.

Divergent Boundaries: African Rift Valley – east African Plate is spreading & has torn Saudi Arabia away from the rest of the African continent forming the Red Sea

Convergent Boundaries What is convergent boundaries?

Convergent Boundaries What are the three types of convergent boundaries? 1. Oceanic-oceanic2. oceanic-continental3. continental-continental nature.nps.gov

Continental convergence form mountain ranges Example: Himalayan Mountains formed by the convergence of the Indian and Eurasian Plates. Convergent Boundaries Continental Convergence: nature.nps.gov

Himalayan Mountain Range destination360.comgeography.howstuffworks.com

Convergence Boundaries: Continental and Oceanic Convergence: Create trenches and volcanic mountains One crust subducts under another.

Pacific Plate & North American Plate form the Aleutian Islands in the Pacific Ocean off the northeast coast of Siberia Aleutian Islands

Andes Mountains geo1202peru.blogspot.com Nazca Plate & South American Plate form the Andes Mountains on the western border of the South American continent

Convergent Boundaries: Oceanic Convergence Creates trenches, volcanic islands, and volcanic island arcs Subduction zone

Located in the Pacific Ocean near Japan. Created by ocean-to-ocean subduction. -Phillipine Plate is subducting under the Pacific Plate Mariana Trench

Plate Tectonics Homework due Wednesday: Annotate article and answer question related to article. Complete sea floor spreading questions. Continue to record seismic activity. Complete questions from plate tectonic worksheet. Quiz: Wednesday Test : Friday

Sea Floor Spreading Model Use the picture below to help understand the sea floor spreading model you made last week. a.What kind of boundary is represented at #1? (slit?) b.What kind of boundary is represented at #2? (slit?)

Transform Boundaries What is a transform boundary?

Transform Boundaries San Andreas Fault By Robert E. Wallace, USGS The Pacific Plate and the North American Plate slide past each other. Create Earthquakes

Plate Tectonics How does it affect climate? * Changed the climate over the last 250 million years by constantly creating geological processes (volcanoes;earthquakes) that produced heat and chemicals in the atmosphere that would promote and support life. Climate keeps most water from freezing. How does it affect life? Plate tectonics promotes diversity among animals by causing isolation due to geographical formations (mountains).

Earth’s Tectonic Plates dpc.ucar.edu