Question 4: Continental drift and plate tectonics [15 marks total The theory of
ID: 117787 • Letter: Q
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Question 4: Continental drift and plate tectonics [15 marks total The theory of continental drift and plate tectonics was introduced by a German meteorologist in 1912 using different lines of evidence. (a) What is the name of this German meteorologist? [1 mark] (b) List at least three lines of evidence that this German meteorologist used to support continental drift and give a short description of each. [6 marks] The theory was confirmed in the 1950's as a result of deep-sea research. In particular the ocean floor magnetic anomaly patterns appeared to be extremely convincing, giving evidence for sea floor spreading (c) What igneous rock type is the ocean floor made of? [1 mark] (d) What is a magnetic anomaly? [3 marks] (e) Explain how the magnetic anomaly patterns around mid-oceanic ridges support sea floor spreading. [4 marks]Explanation / Answer
A. Alfred wegener is the German meteorologist who introduced continental drift.
B. The first evidence he got is on the availability of same fossil samples on different land masses that are far away from each other. According to this, the fossils that are originated in one place are found in other continents that are really far from their source.
He said about pangea which means a single piece of land before dividing. He linked all the topographical features like mountains and concluded that they are all once linked and now got separated.
From the coal samples that are found in Antarctica made him explain that the land is a single mass.
C. Basalt is the igneous rock that made the ocean floor. Because when the volcanoes erupted in the oceanic floor due to the water the Magma cooled rapidly and formed basalt.
D. As we know that earth is a big magnet, there are few places in which the magnetic property is high and low. This difference is called as magnetic anomaly.
E. As the igneous rocks like basalt are high in magentic properties, they show different anomalies which are strong in that place. So when the same magnetic anomaly is found in different places on the sea floor and other anomalies indicate the patterns.
During the spreading the basalt travels far from the mid oceanic ridges and explains it by observing the magentic anomalies.
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