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Transcript of Changing Earth
Oceanic-Oceanic: Mariana Trench or Philippine islands, Aleutian islands (Alaska), or islands of Japan
Oceanic-Continental: Cascade Mtns. (includes Mt. St. Helens) TRANSFORM PLATE BOUNDARY LANDFORM NAMES San Andreas Fault
(in California) DIVERGENT PLATE MOTION:
Plates Spread apart (move away from each other) DIVERGENT BOUNDARY LANDFORMS Ocean: Mid-Ocean Ridges (and Rift Valleys)
Land: Rift Valleys (and Volcanoes) DIVERGENT BOUNDARY: Specific Names of Landforms Ocean: Mid-Atlantic Ridge (down the middle of the Atlantic Ocean) (p. 23)
Land: Great Rift Valley in Africa (p. 27) DIVERGENT PLATE BOUNDARIES What happens to the crust?
New crust is formed (created). CONVERGENT PLATE BOUNDARIES Plate Motion:
Moving together (toward each other) CONVERGENT PLATE BOUNDARY Landforms Continent-Continent: mountains (p. 31)
Oceanic-Oceanic: deep-ocean trenches, island arcs (p. 32 on left)
Oceanic-Continental: deep-ocean trenches, coastal mountains (p. 32 on right) CONVERGENT PLATE BOUNDARY What happens to the crust?
Crust is folded (where plates collide) or is destroyed where plates subduct TRANSFORM PLATE BOUNDARY Plate Motion Scraping past each other TRANSFORM PLATE BOUNDARY LANDFORMS Surface fault TRANSFORM PLATE BOUNDARY What happens to the crust?
Crust is neither created nor destroyed TYPES OF PLATE BOUNDARIES TRANSFORM PLATE BOUNDARY http://www.classzone.com/books/earth_science/terc/content/visualizations/es0902/es0902page01.cfm?chapter_no=visualization Click on the following link to watch the animation: http://www.classzone.com/books/earth_science/terc/content/visualizations/es0808/es0808page01.cfm?chapter_no=visualization Click on the following link to watch the animation: Continental Drift…An Idea Before Its Time Alfred Wegener’s continental drift hypothesis stated that the continents had once been joined to form a single supercontinent. Wegener proposed that the supercontinent, Pangaea, began to break apart 200 million years ago and form the present continents. • Sea Floor Spreading In the 1940’s, scientists began to use sonar to map large areas of the ocean floor
sound waves are sent down from ships on the surface; these waves bounce off the ocean floor, and back to the receiver; the amount of time it takes for the sound waves to go and return allows us to calculate the distance to the ocean floor (mapping is done with computers)
series of ridges near the center of the Atlantic Ocean was discovered;
ridges extended the entire length (north to south) of the Atlantic Ocean
Ridges were also found in parts of the Indian and Pacific Ocean Sea Floor Spreading: The Evidence… 1968, scientists used a research ship to drill cores of rock from the bottom of the ocean floor
the rock was dated by measuring traces of radioactive isotopes left in the rock when it was created; discovered the rock was the youngest at the mid-ocean rift and oldest at the shores of the continents
measured the direction of the magnetic field that existed when the rock hardened. discovered that the Earth’s magnetic field is constantly shifting, leaving alternating bands of rock with reversed magnetic polarity
Based on collected data, Atlantic Ocean spreads about 1.25 cm a year, on average—about the same rate that your fingernail grows Continental Drift http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml Alfred Wegener proposed that the continents were once a single land mass that drifted apart.
Called this supercontinent Pangea, Greek for “all Earth” Matching Mountain Ranges Sea Floor Spreading: The How… Convection current: Boiling-like current of magma in the mantle (the layer below the crust). This current causes the plates to gradually move.
Seafloor Spreading: Magma below earth’s crust rises to the ocean surface through cracks and causes the ocean floor to slowly widen (example: mid-Atlantic ridge) The Theory of Continental Drift Alfred Wegener, 1912 Pangaea The break up
of Pangaea Pangaea What is Pangaea?
Pangaea was the supercontinent Wegner believed existed before the continents separated.
So what made Wegner think the continents were once connected? Continental Drift: The Evidence… shape of the continents suggests that they could fit together like puzzle pieces
same animal fossils are found on continents separated by oceans
matching rock types and structures, including mountain belts that end on one continent and continue on another across the ocean and specific kinds of rocks and ages of each rocks are found on opposite shores of the Atlantic Ocean along coastlines
fossils of tropical plants are found in polar areas, suggesting that the continents now in polar areas were once near the equator
glacial deposits (which only could be created in cold polar areas) are found in tropical areas, suggesting that some continents now in tropical areas were once near the poles. Continental Drift Fossil Evidence Glacier Evidence Wegener’s theory was rejected by scientists because he could not explain what force pushes or pulls continents. Rejecting the Hypothesis Checkpoint: What are three types of evidence Wegner used to support his theory of continental drift? Matching Landforms
Matching shape of continents
Evidence of Different Climate SO WHAT MADE SCIENTISTS CHANGE THEIR MINDS ABOUT WEGNER’S THEORY? As the World Turns… Changes in the Earth’s Crust…Plate Tectonics Evidence for Continental drift Fossils- the same fossils were found on continents separated by oceans
Climate- fossils and rock evidence shows that continents that are now cold were once in a warm climate
Geology- the rocks of separated continents are the same kind or structures match up
Continent shape Sea Floor Spreading More Evidence is Found Click on each of the links to discover more about each of the earth's layers! http://education.sdsc.edu/optiputer/flash/insideEarth.htm http://education.sdsc.edu/optiputer/flash/convection.htm http://www.classzone.com/books/earth_science/terc/content/visualizations/es0805/es0805page01.cfm http://www.echalk.co.uk/Science/physics/convection/convection.html Using a small fish tank filled with water placed over a bowl of hot water and a bowl of ice, the convection currents can be seen using red and blue food dye. Layers of the Earth During the course of this prezi... you will discover many things about our ever changing Earth... Each concept will need to be completely understood and recorded on your Changing Earth foldable... if there is something interesting you find... Be sure to record it in one of the 10 available spots on the front of your foldable... By the time you are finished... You will have... A better understanding of the planet you inhabit... As well as a phenomenal tool to help you pass the quiz at the end of this lesson... Please be sure to read and follow all directions... Your journey is just beginning... What have you learned about the layers of the earth? Did you record anything interesting on the front of your foldable? Are you excited for the next piece of the puzzle? I was afraid of that... Oh well...away we go! The idea of Pangea & continental drift... So in summary... Now isn't that just an ocean of new, fun, and interesting facts! Did you record the new things you learned on the front of your foldable??? Are you ready for more? I knew you would be... It will all start coming together now... But before we can really break this apart... We need to understand... Just exactly what makes this earth of ours tick... Within the asthenosphere, lays the answer to the earth's constant movement... As well as the answer to all of your questions regarding convection currents on the back of your foldable... Convection currents are caused by the very hot material at the deepest part of the mantle rising, then cooling, sinking again and then heating, rising and repeating the cycle over and over. The next time you heat anything like soup or pudding in a pan you can watch the convection currents move in the liquid. When the convection currents flow in the mantle they also move the crust. The crust gets a free ride with these currents. A conveyor belt in a factory moves boxes like the convection currents in the mantle moves the plates of the Earth. Click on the following links to learn more about convection currents! It's the same idea in a lava lamp... But I don't understand... What does all of this molten rock rolling around in the earth have to do with me?? Why do I need to know this? What effect will this ever have on me? But what is all this about tectonic plates and plate boundaries...? Can you be more specific??? You knew I could be... So there it is... Everything you could need to know about our ever-changing Earth... All that is left... Is for you to show me what you know... Your foldable should be COMPLETE... And with it, you will have all you need to demonstrate that you have come away with something new... Please click on the link and take the Quia quiz... This is for a grade... And you only get one shot... http://www.quia.com/web Click this link.
Click on the link titled "Class Web Page"
Log in again.
Then take a look at the videos and games
on the next slide! Take a look at the map of volcano eruptions & label these on your foldable... Don't forget to plot earthquakes as well... Check out this link! http://earthquake.usgs.gov/earthquakes/map/ Label BOTH the Ring of Fire and the Mid Atlantic Ridge on the same map where you drew the arrows showing the direction different plates were moving! To be more specific.. The earth's continental crust is:
Average Density: 2.7 g/cm3
20-25 miles (30-40 km); thickest = 45 miles (70 km)
Consists mainly of igneous rocks
Upper layer: granite rock (lightly- colored, coarse-grain, magma)
Lower layer: basalt and diorite (same composition as granite) The earth's oceanic crust is:
Average Density: 2.7 g/cm3
4-7 miles (6-11 km) below earth's surface & THICK
Made up of: Basalt rock (dark, fine-grained, gritty volcanic rock) The earth's upper mantle is:
Bottom layer = tough liquid rock
Upper layer = stiffer liquid rock (because of lower temp)
Average Density: Between 3.4 and 4.3 g/cm3
7 to 190 miles (10 – 300 km) below the Earth’s surface
Made of silicates of iron and magnesium
And is 2520-5400 degrees F (1400 – 3000 degrees C) The earth's lower mantle is:
Average Density: Between 4.3 and 5.4 g/cm3
190-1800 miles (300-2890 km) below the Earth’s surface
Made of sulphides and oxides of silicon and magnesium
Avg. temp. = 5400 degrees F (3000 degrees C) The earth's outer core is:
Liquid (because is so hot)
Average Density: Between 10 to 12.3 g/cm3
1800-3200 miles (2890-5150 km) below the Earth’s surface
Made of iron and nickel (about 10% sulfur and oxygen)
And is... 7200-9032 degrees F
(4000-5000 degrees C) The earth's inner core is:
Solid (pressures are so great that it cannot melt even though it is so hot)
Average Density: About 15 g/cm3
3200-3960 miles (5150-6370 km below the Earth’s surface)
Made of iron and nickel (some lighter elements)
And is 9032-10832 degrees F (5000-6000 degrees C) Click on the following link to explore the types of plate boundaries.
Be sure to click on ALL 3 arrows. http://sepuplhs.org/middle/iaes/students/simulations/SEPUP_Plate_simulation.swf Check out each of these links to learn more about the lithosphere and the asthenosphere:
http://www.plate-tectonics.org/plate-tectonics/characteristics-of-the-lithosphere-and-asthenosphere.html Did you know that about 90% of the world's earthquakes and 81% of the world's largest earthquakes occur along the Ring of Fire??? How about the fact that the Ring of Fire contains over 450 volcanoes and is home to approximately 75% of the world's active volcanoes??? That's just nuts!!!!!!!!!! http://www.learner.org/interactives/dynamicearth/structure.html Check out any of these earthquake video clips! Watch any of these volcano clips! Play either one of these games! Plate Techtonics Game Show
http://www.heritagekids.info/school/Science/Plate%20Tectonic%20Game%20Show%20Flash.html Plate Techtonics Game
http://www.purposegames.com/game/1806 Japan Earthquake: Helicopter aerial view video of giant tsunami waves New dramatic video: Tsunami wave spills over seawall, smashes boats, cars Japan earthquake makes skyscraper dance Eruption at Kilauea in Hawaii Kilauea Volcano Erupts - Dramatic Video Iceland Volcano erupts - Dramatic Video Etnatao: Icelandic Volcanoes