Cradle of Life: reading assignments. Chapter 2

Chapter 2 of Cradle Of Life describes how the study of the Precambrian fossil record came to be a field of research of its own.

Throughout the pages of this chapter you should:

Try to grasp the sense of deep (geologic) time, and
Get acquainted with the main facts in terms of geology (following the guide questions listed below)

The Floodgates Crack Open
- What is a chert?
  (Cherts have been discussed AND shown in class. Be sure to know everything about them. Integrate the materials from "Cradle of Life" with what you can find on your textbook and lab manual). KNOW your chert!
- Why was the chert that Tyler found on the banks of Lake Superior, Ontario, jet black in color, and NOT rusty-red?
- What might cause different coloration in these cherts?
- What is a thin section?
  (Thin sections are also described in the Lab Manual, chapter 3)
- What observation, made under the microscope, convinced Tyler that these cherts had not been metamorphosed?
  Remember what metamorphism is, and how it can change rocks (see Chapter 2 on your textbook for review)
- Tyler saw something under the microscope that really confused him. What was it?
- Why would the presence of a fossil in these mid-Precambrian cherts make a "stupendous discovery"?
- What is the importance of scientific meetings like the Geological Society of America one that Tyler attended in 1953?
- Why was the article published on the April 30, 1954 issue of Science a monumental "first"?
- How did Timofeev speed up the process of looking at fossils?
- Is there any danger of contamination of the material using these techniques?
- Did the political climate of the time hinder scientific advance?
Famous Figures Enter the Field
- What attracted Preston Cloud and Martin Glaessner to this field of research?
- From what you read on Cradle Of Life, why is the Ediacara Hills Fauna so important?
- What does the Ediacara Hills Fauna (also known as Ediacaran Fauna) consist of? Or, what is the Ediacara Fauna?
- What do we mean by "Fauna"?
- Where are the Ediacara Hills?
The Ediacara Fauna IS important. Sometimes students seem to bypass the reference to the Ediacara Fauna in this paragraph. Please, look for it and be sure you know the answer to all of the previous questions.
A Youngster Joins the Fray
Try to grasp the atmosphere of the publication process and the rush of Barghoorn and Schopf to do so before Preston Cloud
- What passage of George Gaylord Simpson inspired William Schopf as a student?
The Floodgates Open Full Bore
- A lot of skepticism awaited the authors of the papers. Why was that?
- What was also a big problem with the Gunflint organisms?
- What can you say about the Bitter Springs, Australia, fossils? How do they compare to the Gunflint fossils?
- How is Precambrian paleontology different from Phanerozoic paleontology?
- What are the four keys of a search strategy specifically focused on the Precambrian fossil record?
- What happened to the research in this field after the publication of the 1965 landmark papers?

A final note: do not confuse the Gunflint fossils with the Ediacara Fauna, or the Bitter Springs fossils. They are different fossil associations, they come from different ages, they have been found in different rocks, and have different geological significance. Be sure to double check all of these.

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