Aice environmental Management lab evidence for Plate Tectonics

1. 
   Where are the youngest sediments found, compared to the Mid-Atlantic Ridge?
   
2. 
   Where are the oldest sediments found?
   
3. 
   Does the data support the theory of sea floor spreading? How?
   

1. 
   What would be the age in millions of years of an ocean floor rock found 20 kilometers west of the ocean ridge?
   

2. 
   From point A to point B, what happens to the relative age of the rocks?
   

B. continuously increase from A to B

C. decreases from A to the mid-Atlantic ridge and then increases to B

D. increases from A to the mid-Atlantic ridge and then decreases to B

3. 
   What is the average rate of sea floor movement (centimeters per year or cm/year) from the mid-Atlantic ridge to point B. Remember that there are 100,000 cm in a km and to find the rate per year, you will have to multiply the millions of years by 1,000,000. Show all work.
   

4. 
   The Hawaiian Islands vary in age from Maui (1 million years old) to Kauai (5 million years old).
   

About 265 million years ago, a reptile called Mesosaurus lived in just a few places on Earth. This fairly small, lizard-like reptile measured 71 centimeters from its nose to the tip of its tail—or about two thirds of a meter. Its body was long and flexible, perfect for swimming swiftly through the water. Mesosaurus was a hunter of small fish and other aquatic animals. Its webbed feet and long tail worked like powerful paddles as it chased and captured its food. Like all other reptiles, Mesosaurus breathed air, so it had to return to the surface after hunting underwater. Freshwater ponds and lakes were its habitat.

1. 
   What could explain this distribution?
   
2. 
   Describe the kind of environment in which Mesosaurus lived.
   
3. 
   Is it likely that Mesosaurus swam back and forth across the Atlantic Ocean? Explain.
   
4. 
   What could explain the distribution of Mesosaurus fossils?
   
5. 
   Does the case of Mesosaurus support Wegener’s theory of continental drift? Explain why or why not.
   
6. 
   Does the case by itself prove the theory? Explain why or why not
   

The greatest challenge for mountain climbers is Mt. Everest, whose peak rises 8,872 meters above sea level. This is the highest mountain in the world, though many mountains around it are almost as high. Mt. Everest is in the Himalayas, a series of massive ranges that extends 2,500 kilometers across south Asia north of India. The Himalayas cover all or part of the countries of Tibet, Nepal, and Bhutan.

1. 
   What are the Himalayas?
   
2. 
   What was the area of the Himalayas like 40 million years ago?
   
3. 
   How did the movement of plates create the Himalayas?
   
4. 
   What else resulted from the collision of those plates?
   
5. 
   What type of plate boundary exists today along the Himalayas?
   
6. 
   If the Himalayas continue to grow in elevation at their present rate, how tall will Mt. Everest be in another one million years?
   

On our transit to the Mid-Atlantic ridge, we tow a magnetometer behind the ship. Shipboard magnetometers reveal the magnetic polarity of the rock beneath them. The practice of towing a magnetometer began during WWII when navy ships towed magnetometers to search for enemy submarines. When scientists plotted the points of normal and reversed polarity on a seafloor map they made an astonishing discovery: the normal and reversed magnetic polarity of seafloor basalts creates a pattern.

• 
  Stripes of normal polarity and reversed polarity alternate across the ocean bottom
  
• 
  Stripes form mirror images on either side of the mid-ocean ridges
  
• 
  Stripes end abruptly at the edges of continents, sometimes at a deep sea trench
  

1. 
   Was Earth’s magnetic field “normal” or reversed 65 million years ago?
   
2. 
   About how long ago was the last time Earth’s magnetic field reversed?
   
3. 
   Can you see any pattern in how often Earth’s magnetic field reverses? Give reasons for your answer.
   
4. 
   How would this history of reversals show itself on the ocean floor?
   
5. 
   From this graph, when would you predict the next reversal would occur? Give reasons for your answer.
   

1. 
   What are you modeling by pushing the strips up through the base?
   
2. 
   What is being modeled at slits A and B as you push the strips up through the base?
   
3. 
   This model shows what happens at sea floor spreading centers, such as the mid-Atlantic Ridge. List at least 2 good points of this model.
   
4. 
   What are at least 2 reasons why this model is not a good model?
   
5. 
   Seafloor spreading is continuing today along mid-ocean ridges such as the Mid-Atlantic Ridge. Predict what effect this will have on the size of the ocean basin
   

Mid ocean ridge, divergent boundaries the ocean floor has crack that allows molten material to be pushed up through the crack resulting in the ridge

Sea Floor Spreading, ocean floor is spreading due to divergent boundaries allowing the oldest rock to be pushed out and the new rock is being formed closest to the crack (forms the ridges)

Old oceanic crust gets pushed out and may get covered with new material if it is close to the crack

1. Magnetic Strips

2. Rock formation

3. The aging of the rocks

Ocean Trench  Subduction  The oceanic plate slips under the continental plate due to density differences (Plate movement  convection currents)

Sonar device (Map Topography)

Ocean Trench

Sea Floor Spreading