Transcript Seafloor Spreading Lab
Seafloor Spreading Lab 1. What is happening at Slit B? What feature occurs at the corresponding location on the seafloor? • Magma is being forced upward creating new ocean floor. The feature that occurs at slit b stands for the central valley of the mid-ocean ridge. 2. What is happening at Slit A and C? What features occur at corresponding locations on the seafloor? • The oldest ocean floor collides with the continental crust. The more dense oceanic crust sinks back into the mantle. The feature that occurs at slit A and C is a subduction zone or deep ocean trench. 3. If you were to sample and date the rocks along the colored strip starting at Slit B and moving toward Slit A, what change would you see in the age of the rocks? • If you were to sample and date the rocks along the colored strip starting at slit B and moving toward slit A, the rocks would be getting older. 4. If you were to sample and date the rocks along the colored strip starting at Slit C and moving toward Slit B, what change would you see in the age of the rocks? • If you were to sample and date the rocks along the colored strip starting at slit C and moving toward slit B , the rocks would be getting younger. 5. In this model, what do the strips represent? What do the colors represent? • The strips represent the ocean floor. The colors represent the ages of the rocks. 6. How does the ocean floor as shown by the part of a strip close to the center slit (Slit B) differ from the ocean floor as shown by the part near a side slit (Slit A or C)? • The ocean floor as shown by the strip near the center slit is younger, hotter and less dense than the ocean floor farther away. As the floor moves away from the ridge, it cools and becomes denser. 7. How does this difference affect the depth of the ocean? • Since the ocean floor gets cooler and more dense as the material moves toward the side slits, the depth of the ocean floor increases. 8. Why is it important that your model have an identical pattern on both sides of the center slit? • It is important to have identical patterns of stripes on both sides of the center slit because this represents that the ocean floor is expanding. Rock found at the same distance on either side of the mid-ocean ridge would be the same age, have the same composition, and have matching magnetic characteristics. The identical pattern provides evidence for seafloor spreading. 9. What causes the plates to be pulled apart? • As new ocean floor forms at the mid-ocean ridge, older ocean floor moves away from the ridge and this causes the plates to move away from one another. 10. Use your own words to describe the process of seafloor spreading. • At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge. Over tens of millions of years, the process continues until the oldest ocean floor collides with the continental crust. The more dense oceanic crust subducts (sinks) back into the mantle at a deep-ocean trench.