Transcript Warm- Up
Warm- Up Ch. Mid term questions TOC: 106. Tectonic Proof 107. Ocean floor 108. Pg 275 (1-17) Keywords: Paleomagnetism Hot spot Convection current Slab- pull Ridge- push Quiz 1. 2. 3. 4. 5. What are the 3 major zones of Earth according to chemical composition? What are the two types of crust and which is igneous rock is each mostly made of? Provide the 4 pieces of evidence presented by Wegener to defend continental drift. Which later of Earth contains the greatest volume and what percentage of Earth’s volume does it make up? What are the 2 metals that make up the core? Quiz 6. Put the following in order of increasing density: outer core, continental crust, asthenosphere, oceanic crust, 7. What are the 3 types of convergent boundaries? 8. At which type of boundary is crust neither created nor destroyed? 9. If two oceanic plates collide, which plate will go under the other and what is the name for this process? 10. How much water is believed to be in the mantle? Plate Tectonics Dozen or so plates in constant movement 3 different ways plates can interact Worked to explain why continental drift occurred Proof Scientists immediately began testing the new model. There was evidence to support continental drift. Seafloor spreading was observed for plate tectonics. Paleomagnetism would seal the deal Paleomagnetism Earth’s magnetic field is felt by magnetic materials Lava is too hot to be affected but as the rock cools, the poles align Rock points to current poles at time of becoming solid Paleomagnetism Sometimes the poles will “flip” During these times the magnetic moment of the rock formed will be in another direction Flipping of poles is not dangerous Occurs 3-4 times per million years Earthquake Patterns Plate tectonics was supported by the occurrence of deepfocus earthquakes in areas of deep ocean trenches Plate boundaries coincide with earthquake zones Slab movement can be followed down to 700Km Ocean Drilling Deep Sea Drilling project (68- 83) brought up samples; older as distance from boundary increased Confirmed hypothesis of seafloor spreading Youngest crust near ridge; oldest closer to continents Ocean crust up to 180 million years old while continental is up to 4 billion Hot Spots Prove they move Plate dragged across mantle plume Oldest islands furthest away. But How Can’t travel below plates How do we prove the plates move if we don’t know the cause? Evidence was enough to build theory Convection currents are believed to be the main cause Convection Currents Material near the crust becomes more dense, causing it to sink Sinking material flushes less dense material up Cyclical process Creates conveyor belt in the asthenoshere Slab- Pull Plates have enormous mass. Once subduction begins, plate is pulled to the center of Earth Ridge- Push Material forms at the ridge and hardens New material is pulled by gravity down the slope of the ridge LEAST POWERFUL OF THE FORCES Assignment Complete pages 273- 274 with a partner; there is no worksheet just record your measurements in your notebook. For homework complete page 275 (1-17) short answers are fine.