Reconstructing Pangaea

©American Geological Institute. 2001

  1. You can compare the plates forming the Earth's crust to pieces of newspaper torn from the same page. Using the small pieces of newspaper in the envelope consider the following questions:
    1. How would you be able to decide if the pieces all came from the same page?
    2. How could you convince someone else that the pieces came from the same page?
  2. You will need three copies of the diagram — two copies to assemble your models and the third copy for reference. The diagram shows the outline of the continents at sea level, as well as the boundary between the continental crust and the oceanic crust, which in most cases occurs near the continental shelves. The diagram also shows the location of rock formations, mountain ranges, and fossil plants and animals.
  3. Cut out the continents on one copy of the diagram along the edges of the continental shelves (dashed lines). Rearrange the cut pieces on a blank piece of paper as the continents appear today and tape them in place. Draw a border around the map, sketch in and label the Equator and latitude lines at 30° and 60° north and south. Title the map "Present"
    1. Today, is your community in the tropics, subtropics, mid-latitudes, subpolar, or polar ecological region?
    2. Coal deposits originated in the swamps of tropical forests. Where are coal deposits shown on the present-day map?
    3. Where today do you find mountains similar in structure to the Appalachian Mountains?
    4. Where today do you find rock formations similar to those in South America?
    5. Glossopteris is an extinct seed fern that has leaves like ferns of today. It produced seeds too large to travel by air or float on water. Where are fossils of these ferns located today?
    6. Mesosaurus is an extinct freshwater reptile that thrived during the Triassic Period (245 to 208 million years ago). Where are fossils of this reptile found today?
  4. Cut out the continents on another copy of the diagram. Try to arrange the pieces as they would have appeared 250 million years ago. You can do this by matching similar rock formations, mountain ranges, and fossils from continent to continent. Tape the continents to a blank sheet of paper. Draw a border around the map, sketch in and label the Equator and latitude lines at 30° and 60° north and south, and title the map "250 million years ago"
    1. Why do you think the continents do not fit together exactly? Which two continents fit together best?
    2. At what latitude was your community located 250 million years ago? In what ecological region is this?
    3. Many coal deposits were created before 280 million years ago in the tropics. Where were they 250 million years ago? Does this make sense? Explain your answer.
    4. 250 million years ago, did the Appalachian Mountains line up with other mountain ranges that they resemble? Did rock formations in South America line up with other formations that they resemble?
    5. Use your map of the continents 250 million years ago and your map of the present-day location of the continents to explain the present-day distribution of Glossopteris fossils. Remember that the seeds of Glossopteris could not be carried by the wind or float on water.
    6. Use your map of the continents 250 million years ago and your map of the present-day location of the continents to explain the present-day fossil distribution of Mesosaurus. Remember that it could not swim in the salty ocean.
  5. What evidence did you examine that supports the idea that the continents of the Earth have moved during geologic time? Geoscientists often try to figure out the geography of land and sea in the geologic past (paleogeography) using the clues given on your continent puzzle pieces. What additional evidence would you need to be more confident about your "250 million years ago" map?