Thursday, October 15, 2009

Plate Boundery Questions!


1. What are the first 3 types of plate boundaries listed?

Plate boundary zones

Transform boundaries

Convergent boundaries


2. What does the word divergent mean in regard to plate movement? What forces the plates to move apart at divergent boundaries?

Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle.

Picture two giant conveyor belts, facing each other but slowly moving in opposite directions as they transport newly formed oceanic crust away from the ridge crest.


3. Give an example of a specific mid-ocean ridge where seafloor spreading and divergent boundaries occur. What country sits directly on top of this ridge? What are the red triangles that are shown on the map of this country?

Iceland is directly on top of the ridge. They show the mid Atlantic ridge and the Atlantic ridge.


4. What does the word convergent mean in regard to plate movement?

Collision that takes place between two plates which depends on lithosphere.


5. Find the diagrams shown on the website for each of the following kinds of plate boundaries. Label and post the three diagrams on your blog.

a. Oceanic-continental convergence-If by magic we could pull a plug and drain the Pacific Ocean, we would see a most amazing sight -- a number of long narrow, curving trenches thousands of kilometers long and 8 to 10 km deep cutting into the ocean floor.

b. Oceanic-oceanic convergence-As with oceanic-continental convergence, when two oceanic plates converge, one is usually subducted under the other, and in the process a trench is formed. The Marianas Trench (paralleling the Mariana Islands), for example, marks where the fast-moving Pacific Plate converges against the slower moving Philippine Plate.

c. Continental-continental convergence-The Himalayan mountain range dramatically demonstrates one of the most visible and spectacular consequences of plate tectonics.

6. When one plate gets pushed below another plate it is called subduction. What geologic features form on Earth’s surface directly above the subduction zone in the case of:

a. oceanic-continental convergence? Trenches are the deepest parts of the ocean floor and are created by subduction.

b. oceanic-oceanic convergence? In turn, the overriding South American Plate is being lifted up, creating the towering Andes mountains, the backbone of the continent.

c. continental-continental convergence? When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion.

7. What is a transform boundary? What geological disturbance is caused along transform boundaries? Where in North America is there an example of this type of plate boundary? The zone between two plates sliding horizontally past one another is called a transform-fault boundary, or simply a transform boundary. Most transform faults are found on the ocean floor. San Andreas fault zone in California

8. Using the Internet and a focused search, identify the type of plate interaction that caused the following features:

a. Mid-Atlantic Ridge- Is a mid-ocean ridge, a divergent tectonic plate boundary located along the floor of the Atlantic Ocean, and the longest mountain range in the world.

b. Kuril Trench- Is an oceanic trench with a maximum depth of 10,542 meters (34,000 ft).

c. Phillipine Islands- Is an island that has trenches around it.

d. East African Rift Valley- Is an active continental rift zone in eastern Africa that appears to be a developing divergent tectonic plate boundary

e. Red Sea- A long, narrow, landlocked sea that separates Africa from the Arabian peninsula. It is linked to the Indian Ocean in the south by the Gulf of Aden and to the Mediterranean Sea in the north by the Suez Canal.

f. Peru-Chile Trench- Also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometers (100 mi) off the coast of Peru and Chile.

g. Aleutian Islands- A chain of U.S. volcanic islands that extend southwest from the Alaska Peninsula.


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