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WARM-UPS #1 Use your p. 470-484 to answer the questions. Use your p. 470-484 to answer the questions. 1. What type of boundary occurs where plates collide?

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Presentation on theme: "WARM-UPS #1 Use your p. 470-484 to answer the questions. Use your p. 470-484 to answer the questions. 1. What type of boundary occurs where plates collide?"— Presentation transcript:

1 WARM-UPS #1 Use your p to answer the questions. Use your p to answer the questions. 1. What type of boundary occurs where plates collide? 2. What is a transform boundary? 3. What type of boundary occurs when plates separate? 4. What is tension? 5. What is the rising of regions of Earth’s crust to higher elevations?

2 16.1 Restless Continents

3 Continental Drift proposed by Alfred Wegener (German scientist) in the early 1900s proposed by Alfred Wegener (German scientist) in the early 1900s Theory: continents once formed a single landmass (245 million years ago), broke up, and drifted to their current locations Theory: continents once formed a single landmass (245 million years ago), broke up, and drifted to their current locations Called the single landmass Pangaea Called the single landmass Pangaea

4 Continental Drift continued A few years after Wegener, Alexander Du Toit (South African geologist) proposed a theory that Pangaea divided into two supercontinents 180 million years ago A few years after Wegener, Alexander Du Toit (South African geologist) proposed a theory that Pangaea divided into two supercontinents 180 million years ago The northern continent was named Laurasia and the southern continent Gondwanaland The northern continent was named Laurasia and the southern continent Gondwanaland

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6 Evidence for Continental Drift

7 1. Fossil Clues Fossils of Mesosaurus have been found in South America and Africa Fossils of Mesosaurus have been found in South America and Africa Fossils of the tropical fern Glossopteris has been found in Africa, Australia, S. America, India, and Antarctica Fossils of the tropical fern Glossopteris has been found in Africa, Australia, S. America, India, and Antarctica Suggests that these regions were once connected and had similar climates Suggests that these regions were once connected and had similar climates

8 Fossil Evidence

9 2. Climate Clues Glacial deposits in S. America, India, Africa, and Australia show that they were covered with ice and located near the South Pole Glacial deposits in S. America, India, Africa, and Australia show that they were covered with ice and located near the South Pole

10 3. Rock Clues Parts of the Appalachian Mountains are similar to those found in Greenland and western Europe Parts of the Appalachian Mountains are similar to those found in Greenland and western Europe Rock structures in eastern S. America and western Africa are similar Rock structures in eastern S. America and western Africa are similar

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12 Seafloor Spreading

13 Theory of Seafloor Spreading Proposed by Harry Hess in the 1960s Proposed by Harry Hess in the 1960s Process by which new seafloor forms as magma rises toward the surface and solidifies Process by which new seafloor forms as magma rises toward the surface and solidifies As tectonic plates move away from each other, the seafloor spreads apart and magma fills in the gap As tectonic plates move away from each other, the seafloor spreads apart and magma fills in the gap Occurs at the mid-ocean ridge Occurs at the mid-ocean ridge

14 Evidence for Seafloor Spreading Youngest rocks are located near the mid- ocean ridge and the rocks become older as you get farther from the ridge on both sides Youngest rocks are located near the mid- ocean ridge and the rocks become older as you get farther from the ridge on both sides Rocks on the seafloor show magnetic reversals in strips parallel to the mid- ocean ridge Rocks on the seafloor show magnetic reversals in strips parallel to the mid- ocean ridge

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