Geology 001B West Valley College

Historical Geology R. Lopez

Study Questions: Chapter 11 pages 285-312

Origins of the Universe, Solar System, Earth, and Life; Plus the Archean Eon

1) What are the general concepts regarding the Big Bang?

2) Stars are burning spheres of Hydrogen. True or False.

3) What is nuclear fusion and where does it take place?

4) What are the implications of nuclear fusion of all elements heavier than hydrogen?

5) What is a supernova?

6) Our solar system started out as a Solar Nebula. A nearby supernova explosion rocked our solar nebula by adding more heavy elements and causing it to spin? True or False.

7) Earth formed by the accretion of planetesimals. What is accretion and what are planetesimals?

8) After accretion, Earth experienced gravitational compression. What happened to the denser elements like Fe and Ni during this process? What happened to lighter elements like Si and Al?

9) How did the Moon form? What are the criteria scientists use for this origin of the Moon? (See page 294)

10) How did the Earth’s first atmosphere form?

11) Be able to define “outgassing”.

12) Outgassing produced some of the oceans water; however, recent research has shown that much of the water on this planet was brought here by__________.

13) Beginning at about 2.0 billion years ago, the first ancestral plants began to pump oxygen into the atmosphere via photosynthesis. How did this process affect Earth’s atmosphere?

14) When did Earth’s atmosphere become oxygenated?

15) If photosynthesis was widespread by 2.0 Ga, why did the atmosphere not become oxygenated until about 1.5 Ga?

16) What are the three hypotheses regarding the origin of life? Explain each in two to three short sentences.

17) The second hypothesis states that the origin of life was from an external source. What may have brought life to our planet?

18) What are anaerobes and what is chemosynthesis? What are the names of these living oraganisms?

19) In absolute age, what is the time span of the Archean Eon?

20) For the first 100 Ma after accretion, Earth was a molten homogenous planet. What were some of the contributors this high heat flow?

21) What are greenstone belts? (see page 302)

22) What are sialic or felsic rocks?

23) What is an ultramafic rock?

24) What was the composition of Earth’s first oceanic crust, where did it form, and what was its lateral extent?

25) How do geologists determine the age of old rocks that contain no fossils.

26) What is radiometric or isotopic age dating?

27) What are hot spots and how are they inferred to generate less mafic to eventually felsic crust? (see page 298 and Figure 11-15)

28) What is the difference between a craton and a Precambrian shield? (see page 289, Figure 11-2)

29) Greenstones are used as a criteria for what tectonic setting in the Archean Eon?

30) What is cratonization and when were cratons widely exposed?

31) What sequences of rocks indicate that at least one large continent existed before 3.0 Ga, well before the cratonization events? Where are these rocks found today?

32) What is the age of the oldest fossil? (See page 306)

33) What are prokaryotic cells? (see pages 70-71)

34) What are stromatolites? (see page 321)