Transcript File
9/11- Geo Engage • Write down 3 characteristics of the United States that you enjoy. – Think about things that you can do here that you may not be able to do in other countries. Bell Ringer Take out a sheet of paper, put your name on it. Write your answer to the questions. 1. What type of tectonic activity made Hawaii? 2. What activity within the mantle causes plate movement? 3. What type of erosion created the Great Lakes? 4. What type of plate boundary is the San Andreas fault in California. 5. What type of external force of change carries away pieces of rock and creates sediment? Earth is composed of 3 layers: 1. Core 2. Mantle 3. Crust 1. Core (inner & outer) – made of iron & nickel a. inner – super hot solid b. outer – super hot liquid -temperatures can reach 8,000*F 2. Mantle -hot, dense mostly liquid rock -pockets of magma (rise & fall) -made of silicon, aluminum, iron, magnesium, and oxygen 3. Crust -rocky shell which forms earth’s surface -broken into dozen slabs of rock called plate -these plates carry oceans & continents -Continental Drift : *super-continent was called Pangaea PANGEA -Plate Tectonics – term to describe the activities of continental drift and magma flow which create many of Earth’s physical features *plates crash into each other, pull apart, or grind and slide past each other (about 4 inches or less per year) -Why do plates move? -convection currents *hotter material is less dense & rises (toward crust of Earth) *cooler material is more dense & sinks (toward core of Earth) *creates continuous circular motion/movement Why might a scientist want to study plate tectonics? Divergent Boundary -Plates move apart (rift) from each other (tension) 1. Continental-Continental = creates gap (rift valley) in which water can flow in *ex: Red Sea; Great Rift Valley 2. Oceanic-Oceanic = magma rises up & creates new crust on edges of the 2 plates -enlarges the ocean floor & forms underwater mountain ranges called ocean ridges *example: Mid-Atlantic Ridge Convergent Boundary In general: - Plates move toward each other & collide (compression) - One plate is forced below the other (subduction) 1. Oceanic-Continental -subduction occurs = heavier sea plate dives beneath lighter continental plate *sea plate begins to melt into magma pressure builds magma bursts thru crust to form volcanic mtns *ex: Andes Mountains in S. 2. OceanicOceanic -subduction occurs *sea plate begins to melt & magma rises to ocean surface in form of volcanic islands *example: Philippine islands- 3. ContinentalContinental -pressure builds until one plate is subducted *sometimes sinking plate melts & rises as volcanic mountains are formed *example: Himalaya mountains Transform Boundary -Plates slide past each other along faults (cracks in the earth’s crust) - Crust is pulled and stretched (tension) until tension is released (Earthquake) -example: San Andreas Fault in California HOT SPOTS -Magma rises thru the tectonic plate -The magma erupts on the surface as lava & hardens to form volcanic islands Animations Hot Spot Earthquakes & Tsunamis Guess the Tectonic Activity! Oceanic-Oceanic Convergent Oceanic-Oceanic Divergent Transform Continental-Continental Convergent Continental-Continental Divergent Oceanic-Continental Convergent