Download
1 / 24
240 likes | 707 Views
Table of Contents. Chapter 7: Plate Tectonics. Section 1. Continental Drift. Continental Drift. Evidence for Continental Drift. If you look at a map of Earth’s surface, you can see that the edges of some continents look as though they could fit together like a puzzle. Continental Drift.
E N D
Table of Contents Chapter 7: Plate Tectonics Section 1. Continental Drift
Continental Drift Evidence for Continental Drift • If you look at a map of Earth’s surface, you can see that the edges of some continents look as though they could fit together like a puzzle.
Continental Drift A. Pangaea 1. German meteorologist Alfred Wegener (VEG nur) proposed the hypothesis of continental drift in 1912. 2. According to the Wegener’s hypothesis of continental drift, continents have moved slowly to their current locations.
Continental Drift A. Pangaea 3. Wegener suggested that all continents once were connected as one landmass that broke apart about 200 million years ago. 4. He called this large landmass Pangaea (pan JEE uh), which means “all land.”
Continental Drift B. A Controversial Idea 1. Wegener’s hypothesis on continental drift was controversial idea. He did not have enough evidence. Click image to view movie.
Continental Drift B. A Controversial Idea 2. Wegener proposed that the continents plowed through the ocean floor, driven by the spin of Earth. 3. Physicists and geologists of the time pointed out that continental drift would not be necessary to explain many of Wegener’s observations. 4. It wasn’t until long after Wegener’s death in 1930 that his basic hypothesis was accepted.
Continental Drift C. Fossil Clues 1. Fossils are the remains, imprints, or traces of prehistoric organisms. They can tell when and where organisms once lived and how they lived. 2. Animal fossils offer one clue that the continents might have been joined together millions of years ago.
Continental Drift C. Fossil Clues 3. For example, fossils of the reptile Mesosaurus have been found in South America and Africa.
Continental Drift C. Fossil Clues 4. This swimming reptile lived in freshwater and on land. 5. How could fossils of Mesosaurus be found on land areas separated by a large ocean of salt water? 6. Wegener hypothesized that this reptile lived on both continents when they were joined.
Continental Drift D. A Widespread Plant 1. Another fossil that supports the hypothesis of continental drift is Glossopteris (glahs AHP tur us). 2. This fossil plant has been found in Africa, Australia, India, South America, and Antarctica.
Continental Drift D. A Widespread Plant 3. The presence of Glossopteris in so many area also supported Wegener’s idea that all of these regions once were connected and had similar climates.
Continental Drift E. Climate Clues 1. Scientists have found fossils of warm-weather plants on the island of Spitsbergen in the Arctic Ocean. This is one of the coldest place on Earth. 2.To explain this, Wegener’s hypothesis of continental drift proposed that Spitsbergen Island drifted from tropical regions to the arctic.
Continental Drift F. Rock Clues 1. Glaciers are large, slow moving bodies of ice on land. 2. Glacial deposits and rock surfaces scoured and polished by glaciers are found in South America, Africa, India, and Australia. 3. This shows that parts of these continents were covered with glaciers in the past.
Continental Drift F. Rock Clues 4. Similar rock structures are found on different continents. 5. For example, parts of the Appalachian Mountains of the eastern United States are similar to those found in Greenland and western Europe. 6. Rock clues like these support the idea that the continents were connected in the past.
Continental Drift G. How could continents drift? 1. Although Wegener provided evidence to support his hypothesis of continental drift, he couldn’t explain how, when, or why these changes took place.
Continental Drift G. How could continents drift? 2. Because other scientists could not provide explanations either, Wegener’s idea of continental drift was initially rejected. 3. After Wegener’s death, new technology provided new evidence. New ideas about continental drift were developed. One of these ideas is called seafloor spreading. You’ll learn more about this in the next section.
Section Check Question 1 __________ is the hypothesis that continents have slowly moved to their current locations. A. Continental drift B. Mid-ocean shifting C. Pangaea D. Seafloor spreading
Section Check 1 Question 2 Who proposed the hypothesis of continental drift? A. Esker B. Gagarin C. Hess D. Wegener
Section Check 1 Question 3 What is Pangaea?
Section Check 1 Q 1. Answer The answer is A. Continental drift is the theory that the continents have slowly moved. Seafloor spreading is a process that would help explain how the continental drift might occur.
Section Check 1 Q 2. Answer The answer is D. Wegener proposed the hypothesis of continental drift. Hess theorized that the seafloor is spreading.
Section Check 1 Q 3. Answer Pangaea means “all land” and is the name that Wegener used to refer to the one large landmass that he believed existed before it broke apart into continents.
