Environmental Quiz 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.
Evidence for Continental Drift
Matching shapes of continental slope, fossil evidence, similar rock types, ages and mountain ranges, evidence of climate change, earthquake and volcanic activity, sea floor spreading, and magnetic records in rocks
Alfred Lothar Wegener
Proposed theory of continental drift (1912) didn't explain why the continents move
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 increase. A and C are deeper, B is shallower.
Which 2 continents have the most obvious fit of coastlines?
South America and Africa
Pangea
Supercontinent
Which fossil occurs on the most landmasses? What does this suggest about when these particular continents broke up?
The glossopteridales this gives us more understanding about the study of plant and animal distribution through the years
How does the ocean floor as shown by the part of the 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 neat 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 and sinking.
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 and is being recycled. The feature that occurs at Slit A and C is a subduction zone or deep ocean trench.
If you were to sample and date the rocks along the colored strip starting at Slit B moving toward Slit A what change would you see in the age of the rocks?
The rocks would be getting older
If you were to sample and date along the colored strip starting at Slit C moving toward Slit B what change would you see in the age of the rocks?
The rocks would be getting younger
In this model what do the strips represent? What do the colors represent?
The strips represent the new ocean floor and colors represent the magnetic orientation of the rocks.
What is the idea of continental drift?
The theory that explains how continents shift on the earth's surface
How were the fossil symbols and mountain belts helpful in deciding where to move the continents?
You can see how they were placed together
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. CONVECTION OF MAGMA
Use your own words to descibe 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 curst subducts (sinks) back into the mantle at deep ocean trench.
Why don't the present shapes of the continents fit perfectly into a supercontinent?
Because they all broke apart
Why is it important that your model have an identical pattern 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.
