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Continental Drift. Lesson in Earth Science Mr. Fluharty. Pangaea.
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Continental Drift Lesson in Earth Science Mr. Fluharty
Pangaea Ever since the development of accurate maps of the continents, a few people speculated that the continents were once just one large land mass called Pangaea. This idea was based on the shape of the continents and how they could be put together like the pieces of a puzzle.
Alfred Wegener Alfred Wegener (1880-1930) was a German scientist who weaved together seemingly dissimilar, unrelated facts into a theory, which was remarkably visionary for the time. Wegener's scientific vision sharpened in 1914 as he was recuperating in a military hospital from an injury suffered as a German soldier during World War I. Like others before him, Wegener had been struck by the remarkable fit of the coastlines of South America and Africa. But, unlike the others, to support his theory Wegener sought out many other lines of geologic and paleontologic evidence, such as the location of fossils and rock layers on different continents. Over geological time, Pangea split apart and parts of it moved away to form today’s continents. Today, this idea is called continental (kon-ti-NEN-tul) drift. “Drift” refers to the idea that the continents slowly moved away from each other, or drifted apart. Continental Drift Simulation Continental Drift Simulation
Procedure • Individually, carefully read each statement on the worksheet, “Analyzing Evidence: Continental Drift.” • On the left side of the worksheet mark whether you think the statement is or is not evidence. • Cross out each statement that you have decided was not evidence. You will no longer consider these statements. • Now, using only the statements that are evidence, on the right side, mark whether you think each piece of evidence does or does not support the idea that continents have moved. • With your group, discuss: • whether you identified a statement as evidence or not. • how each statement you checked as evidence either supports or contradicts the idea of continental movement.
Statement 1 supports the idea that continents moved because it shows that the same kind of plant was found in different parts of the world. Since plants can’t move, one explanation is that these different parts of the world were once connected. (Note that the unlikelihood of the seeds of the Glossopteris plant being distributed by wind or water should have come up in the follow-up discussion of the previous activity.) • Statement 2 supports the idea that the continents have moved, because it helps explain why places with warm climates today could have had cold climates in the past. It also proposes the formation of a single large ice sheet at that time rather than several different ice sheets. • Statement 5 supports the idea that continents have moved because it shows a pattern of geological features in line with the suggested single land mass.
Statement 6 supports the idea that continents have moved because it is highly unlikely that rock layers in two different parts of the world, affected by different forces, formed exactly the same sequence of layers and fossils if they had not been joined. Statement • Statement 8 supports the idea that continents have moved because it shows how precisely two of the continents could have once been attached. (If they were not attached, how could they fit so well?) • Statement 9 supports the idea that continents have moved because it shows that the continents are now moving. This means that they could have moved in the past. Over billions of years, a few centimeters per year could result in a distance of thousands of kilometers. • Statement 10 supports the idea that continents have moved because it shows the same worm fossil in different parts of the world. One explanation for finding the same worm fossil in places that are so far apart and have such different climates today is that these areas were connected and had the same climate.
Fossils Found on Different Continents (that could not swim) • Glossopteris: a fern found on the southern continents: South America, Africa, Asia (India and Madagascar only), Antarctica, and Australia. • Cynognathus: a land reptile found in South America and Africa • Lystrosaurus: a land reptile found in Africa, Antarctica, India, and Madagascar • Mesosaurus: a freshwater swimming reptile found in southern Africa and South America
