33 planet & humanity

33 planet & humanity - CHAPTER 33 THE PLANET AND...

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CHAPTER OUTLINE I. Introduction A. Discussion on the Earth’s age 1. How Earth acquired its moon 2. Cooling of Earth’s surface 3. Pangaea (Figure 33-1) B. Ocean and atmosphere 1. Water covers about 70 percent of Earth’s surface 2. Will Earth be able to retain its life-giving oceans is discussed 3. Evolution of the atmosphere 4. Photosynthesis 5. The Cambrian explosion —the burgeoning of marine organisms in unprecedented diversity (Table 33-1) C. Fire and ice 1. Today a major volcanic eruption is rare enough to make the news 2. One billion years ago the Earth’s crust was subject to huge bursts of volcanic activity 3. Such volcanic activity caused mass depletions —loss of diversity through a failure to produce new species 4. Three mass extinctions are known to have occurred over the past 500 million years 5. Pangaea began to fracture between 180 and 160 millions years ago 6. The Pacific Ring of Fire —the ocean-girdling zone of crustal instability, volcanism, and earthquakes 7. The ice ages a) One occurred during the Permian Period, while Pangaea with still a super- continent b) The Duyka Ice Age was a time of great extinctions and occurred during the Permian Period c) While Gondwana was glaciated, the South Pole was positioned not far from the south-east coast of present day South Africa (Figure 33-3) 8. The Mesozoic Era a) Tropical warmth replaced Arctic cold b) Moisture and precipitation abounded c) Atmospheric oxygen increased as luxuriant forests spread d) The age of the dinosaurs, first marsupials and angiosperms appeared 9. After landmasses separated species were isolated and evolved into distinctive forms D. Sudden death 1. About 65 million years ago Earth is impacted by a carbonaceous meteorite a) Hit what is today the northwestern edge of Caribbean Mexico’s Yucatan Peninsula b) Consequences were catastrophic c) The most recent of the planet’s great extinctions began 2. The meteorite’s impact divides two Earth periods: the Cretaceous and the Tertiary a) Some small animals managed to survive b) This period boundary is called the KT boundary c) Started the sequence of events that led to the appearance of Homo sapiens
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33 planet & humanity - CHAPTER 33 THE PLANET AND...

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