Cradle of Life: reading assignments

Chapter 3 deals mainly with the geological significance of the oldest fossils found on our planet.

The chapter also describes some mistakes that scientists may make during the process of discovery, and some of the obstacles they have to face along the way. Both mistakes and obstacles significantly slow down the pace of scientific research (that is true for every field of science, not just for geology: every field has its own set of factors that may come in and complicate the picture).

In our specific case, which is the hunt for the oldest fossils, geologists and paleontologists have to face difficulties that originate in processes related to both living organisms (Biology) and the physical and chemical environment (Geology). (Be sure to know what these processes are when studying the relative paragraphs on Cradle Of Life).

Dr. Schopf further enriches this chapter by adding a whole section on general, fundamental questions that may arise when other people, whether scientists, students and scholars, or the general public, are exposed to a new scientific find such as this. Be sure to read and understand his reasons and then proceed to his section on the "Top 10" most asked questions he hears during or after his public talks (see below).

Finally, Dr. Schopf uses his nice colloquial style to introduce a few very important points for each one of the "Top 10" questions. For these questions, of course, he provides an answer. It is your task to read the chapter and extract those important points.
As a general guideline, I am reproducing here the list of the "Top 10" questions, and the main focus for each one of them:

1 - How do you know where to hunt for ancient fossils?
In this paragraph you find a description of the importance of land exploration and age determination.
2 - How can you tell whether a rock is likely to contain microscopic fossils?
In here you encounter again the term "stromatolite". Know what a stromatolite is.
We have already seen images of stromatolites during the lecture on sediments and sedimentary structures.
3 - What signs of ancient life do you search for?
In this paragraph you find a description of three lines of evidence for ancient life.
Be sure to know the details for each of them.
4 - How do you know exactly where these rocks came from?
This paragraph deals with the importance of precision and accuracy in science.
5 - How can you know the age of the Apex fossils so precisely?
We briefly touched upon numerical methods for rock dating in class. Read this paragraph to get a sense of what Dr. Schopf has been doing. Start to get ideas about carbon 14 (¹⁴C) and its limitations, and study the significance of Figure 3.9 on page 89. Are we really dating the fossils in this case, or are we dating something else? If so, what exactly?
6 - What was the Earth like when the Apex organisms were alive?
A very nice example of how we can use our geologic knowledge to reconstruct an ancient environment.
7 - How can you prove that the fossils are actually as old as the rocks?
Again, the importance of accuracy and precision, applied this time to a different theme.
8 - How do you know the Apex objects are fossils, and not mineralic look-alikes?
A very important paragraph: how can we recognize and identify ancient life forms within a rock?
9 - What kind of organisms are they, and why do they matter?
Study the whole paragraph but concentrate for now on the "why do they matter" part.
10 - Will older fossils ever be found?
This paragraph is simply descriptive and outlines how in science we should never take terms as "no way" or "impossible" for granted.

The paragraph "The oldest fossils known" is a very brief but essential summary of the main points outlined throughout the whole chapter. Once you arrive to this point, be sure to use the paragraph as a frame of reference for the whole chapter when you prepare for the quiz.

A general suggestion on how to read these materials: read the title (what is the chapter about), the introduction (a wider description of what is to come), go over the titles of the paragraphs and go directly to the end paragraph. This procedure will give you a general frame in which you will be able to fit concepts, ideas and anything else you want to get out of what you read.

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