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Bang! You're Alive!

History of the Earth Worksheet

1. What is the “Big Bang” theory?
   
   
   
   
2. What elements were most abundant in the universe shortly after the Big Bang?
   
   
   
   
3. In the late 1920s, American astronomer Edwin Hubble made an important discovery that supports the Big Bang theory. What was this discovery?
   
   
   
   
4. According to current theory, after the Big Bang matter collected into clouds. How did stars form in some of these clouds?
   
   
   
   
5. What are “planetesimals,” and how are they relevant to the origin of the Earth?
   
   
   
   
6. According to current theory, about how long ago was the Earth formed?
   
   
   
   
7. How old are the oldest known rocks on Earth?
   
   
   
   
8. As the Earth was being formed, materials in the developing planet were kept in a molten state by intense heat. What was the source of this heat?
   
   
   
   
9. Unlike the Earth, the moon has only a tiny metallic core. What theory for the moon’s formation provides an explanation for this observation?
   
   
   
   
10. What were the first known living organisms on Earth and when did they appear?
    
    
    
    
11. Why haven’t scientists been able to measure the age of the Earth by measuring the age of the Earth’s oldest rocks?
    
    
    
    
12. Where are Earth’s oldest rocks found?
    
    
    
    
13. What is the lithosphere?
    
    
    
    
14. What is the theory of plate tectonics?
    
    
    
    
15. What are divergent boundaries, convergent boundaries, and transform boundaries?
    
    
    
    
16. What are Laurasia and Gondwanaland?
    
    
    
    
17. Who was Alfred Wegener, and what theory did he propose?
    
    
    
    
18. Why did scientists reject Wegener’s theory?
    
    
    
    
19. What are five observations or lines of evidence that support Wegener’s theory? Which of these was key to gaining widespread acceptance for the theory?
    
    
    
    
20. Plate tectonics provides the basis for predicting what geologic events that are of direct importance to human safety?
    
    
    

Major Events in Earth’s History to be Included in Timelines:

• Formation of Earth begins as dust, planetesimals, and meteoroids start to condense
  
  
• The moon is formed
  
  
• Torrential rains form oceans
  
  
• First living organisms appear
  
  
• First photosynthetic organisms appear
  
  
• Cyanobacteria proliferate and begin to add oxygen to Earth’s atmosphere
  
  
• Protoctists appear
  
  
• Eukaryotic algae appear
  
  
• First multicellular animals appear
  
  
• Cambrian “explosion” of animal diversity
  
  
• Ordovician extinction of more than 50% of all marine animal species
  
  
• Devonian extinction of more than 50% of all marine animal species
  
  
• Permo-Triassic extinction of more than 95% of all species
  
  
• First mammals appear
  
  
• Dinosaurs dominate
  
  
• Asteroid impact induces Cretaceous-Tertiary extinction
  
  
• Humanoids appear