Unit 4.2 Test Review Earth and Its Layers 1. Label the layers of the earth. oceanic crust continental crust lithosphere asthenosphere mantle outer core inner core 2. Complete the Following Table about Earth s layers Layer Composition Thickness State of Matter Crust O 2, Si, Al, Ca, Fe, Na, K, Mg 5 to 40 km Solid Mantle Si, O 2, Fe, Mg 2,900 km Solid Outer Core Fe, Ni 2,250km Liquid Inner Core Fe, Ni 1,200 km Solid
3. In which layer do convection currents occur? the mantle (asthenosphere) 4. When a solid can move like a liquid, it is called plasticity. 5. Explain how convection currents in the mantle move the crust above. The heating and cooling of the asthenosphere through convection currents set in motion the asthernosphere to be able to move like a fluid even though it is solid (plasticity). The lithospheric plates sit atop the asthenoshere, and thus when the asthenosphere moves, the plates (crust) move as well. 6. What two elements comprise most of Earth s crust? O 2 and Si (SiO 2, silicon dioxide) 7. What provides the force that moves tectonic plates? convection currents Plate Tectonics 1. Describe the theory of Plate Tectonics. The theory states that pieces of Earth s lithosphere (plates) are in constant, slow motion, driven by convection currents. The convection currents cause the asthenosphere portion of the mantle to be able to move like a liquid even though it is solid. Because the lithosphere is atop the asthenosphere, plate movement occurs.
2. Label the following plates from map below. xa.xxxx XB.x x.xx xxe. xxc.xx D. xxxx x xxf.xxx A. Eurasian Plate D. South American Plate B. North American Plate E. African Plate C. Pacific Plate F. Antartic Plate
Plate Boundaries 3. Match the following plate boundaries with the correct description. A plate boundary in which two plates move away from other. A plate boundary in which two plates move past each other in opposite directions. A plate boundary in which two plates move toward each other. Convergent, Divergent, and Transform Boundaries 4. Two geologic events that can occur when two plates converge are mountain building and deep-ocean trenchs (subduction)_. 5. What is sea floor spreading? The process by which molten material adds new oceanic crust to the ocean floor 6. We call underwater mountain chains that run through oceanic crust mid-ocean ridges. 7. In sea floor spreading, new crust forms at mid-ocean ridges while older crust is pushed away from the ridge.
8. If new oceanic crust is continually being created why isn t the Earth getting bigger? Other parts of the oceanic crust is subducting and melting back into the mantle 9. Describe subduction? the process in which one plate converges with another plate and the denser plate is forced under the less dense plate. The plate that is forced under is then recycled by Earth s inner layers 10. At a convergent boundary of an oceanic and a continental plate, the oceanic plate will subduct under the continental plate. What will form above the subduction zone? a deep-ocean trench 11. At a convergent boundary, a collision between two pieces of continental crust of the same density produces mountains. 12. Continental crust is _more / less _ dense than oceanic crust. 13. When two plates slide past each other in opposite directions they can cause earthquakes such as those found along the San Andreas Fault in California. 14. A stress is a force that acts on a rock to change its shape or volume. 15. A fault is a break in the crust where slabs of crust push past each other. Rocks on both sides of a fault can move up, down, or sideways depending in the type of stress.
16. Volcanic eruptions occur along the edge of plate boundaries where plate movements allow magma to reach the surface through cracks in the crust. 17. Fill in the Plate Boundaries chart below: Type of Boundary Crustal Formation Example Oceanic Oceanic 1. Trench Aleutian Islands 2. Volcanic Islands Convergent Oceanic - Continental 1. Trench 2. Volcanic Mountains Andes Mountains Continental Continental 1. Folded Mountains Himalayan Mountains Divergent 18. Rift Valleys 19. Mid-Ocean Ridges Mid-Atlantic Ridge Transform Faults San Andreas Fault
Label each of the following: divergent boundaries, convergent boundaries, trenches, mid-ocean ridges, and faults divergent convergent convergent trench trench faults mid-ocean ridge