Just how deep does the ocean go? Way further than you think. This animation puts the actual distance into perspective, showing a vast distance between the waves we see and the mysterious point we call Challenger Deep.
Directions: Watch the video and complete the graphic organizer. Bullet points are fine.
The theory of plate tectonics has evolved over the past 100 years as scientists have discovered new pieces of evidence. In the early 1900s, Alfred Wegener first proposed the theory of continental drift, which explained that all of the continents had once been connected in one massive supercontinent that eventually split and drifted apart.
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Wegener made several observations that supported this theory; such as, fossil evidence and matching coastlines. Despite all the evidence Wegener had suggesting the continents were once together, he could not describe how or why they would move apart, and many scientists dismissed his theory. Wegener’s theory received the support it needed during the 1960s when scientists discovered seafloor spreading. Scientists were able to use a new technology called echo sounding to find ocean features such as trenches, seamount chains (mountains on the seafloor), and mid-ocean ridges.
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Question 5
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What types of evidence did Wegener find to support his theory that the Earth was once a giant supercontinent?
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Seafloor spreading creates new ocean floor. Seafloor spreading is a phenomenon by which magma from Earth’s mantle, the layer beneath the crust, wells up at the mid-ocean ridge, pushing the ocean floor apart - this is called rifting. When the magma reaches the surface of the ocean crust, it cools and solidifies into igneous rock. This makes new oceanic crust in the center of the mid-ocean ridge.
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Question 11
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List out the steps in order by which the sea floor spreads.
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Question 12
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What happens to older oceanic crust as it converges with continental crust? Which is denser based on the evidence of what occurs?
Sentence Starter: According to the text, when older oceanic crust converges with continental crust... The crust that is more dense is _______ because...
Trim End | 03:02
Question 13 | 00:18
Question 21 | 00:27
Question 14 | 00:44
Question 15 | 01:10
Question 16 | 01:17
Question 17 | 01:31
Question 18 | 01:53
Question 19 | 02:35
Question 20 | 03:00
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Question 13
00:18
Question 21
00:27
Question 14
00:44
Question 15
01:10
Question 16
01:17
Question 17
01:31
Question 18
01:53
Question 19
02:35
Question 20
03:00
Question 6
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Alfred Wegener could not describe how the continents were drifting and spreading apart.
How did scientists later in the 1960's discover how continental drift works and what tools did they use to discover this process?
