Antiquity of the Earth and Life (August 22 & 24)

Geologic time is a fascinating topic. It is so unimaginably long it has been called “deep time”. Please learn the Geologic Time Scale as soon as possible because it is the chronological language of this course. Because you certainly don’t want to memorize all those terms, I’ve posted a pdf version of our required-time-scale. You will see that I recognize the Ediacaran before the Cambrian, and the Paleogene and Neogene instead of the old Tertiary. You need to know only the eras, periods, and Cenozoic epochs. (For the professional chart, see this beauty. You don’t need to know all these names!) William Smith was an Englishman responsible in many ways for the principles behind geologic time. James Hutton was a Scot who first effectively described and applied the concept of “uniformitarianism” in geology, which requires vast amounts of time.

Geologists distinguish between relative and absolute time, with the first being the ordering of events, and the second using measurements of time. We will most often use relative time (such as the “Cretaceous Period”) in this course, but also occasionally cite absolute time (“65 million years ago”).

The concepts of radioactive decay and its use in the dating of Earth materials take some time to master. Wikipedia has an excellent explanatory website on radiometric dating. (I’m a Wikipedia fan and editor, by the way.) A nice online radioactive decay simulation provides a visual of the process. Set the number of atoms high (I use 1600) and the time long (I use 3.0) Turn on “both” to see atoms and graph. A more detailed explanation of how half-lives are really calculated is shown here. See what I have spared you? Fortunately we have handy online calculators for radioactive decay.

As a preview of what’s coming, I give you the evolution of Homer Simpson!

You may not be surprised to learn that the scientific framework of this course is considered a lie or delusion by just over a third of Americans (which is, in fact, a new low point). “Young Earth Creationists” believe that the Earth and the Universe are a few thousand years old, and that evolution did not occur. This is radically different from the cosmological and evolutionary models supported by scientists. Creationist arguments sometimes appear scientific, but you will quickly see that they are based on misconceptions, misrepresentations, mysteries, and zealotry. For example, take a look at this page citing “evidence for a young Earth” from Answers in Genesis. These are the people who produced the multimillion-dollar Creation Museum in Kentucky (“Prepare to Believe”). Check out this visit I had with First-Year Seminar students. Don’t miss the comments by Answers in Genesis officers). These are the same people who spent millions building a full-scale version of the Ark. We will not be covering creationist arguments directly in this course (we have real science to do), but I will always answer any questions you have about them. I am an evolutionary paleontologist and geologist, but please be assured that you will not be judged or graded on your personal beliefs. What you believe is always your business; what you understand about evolution and the history of life is mine.

The new Time Scavengers blog is an excellent resource for geology students, especially those interested in paleontology. University of Tennessee graduate students Jen Bauer and Adriane Lam have put together a fantastic collection of articles, teaching aids, and links just for students like you!

Finally, have a look at this website: From the Big Bang to the World Wide Web. You will have fun exploring this site. Great theme song.

A trilobite from the Middle Cambrian of Utah.

Geology in the News —

If you want some early preparation for the first part of this course, try the wonderful Crash Course in Astronomy, starting with this episode about Big Bang Cosmology. Note that it starts with Darwin!

Our big toes were the last parts of our feet to evolve. You’ll see why much later in this course. A related question is always what’s up with our littlest toes. Are we losing them?

Viruses, phytoplankton and clouds. How would have guessed they are connected? A common type of oceanic phytoplankton (coccolithophores) covers itself with tiny mineralized (calcite) plates. Some get infected by a virus, which causes them to shed the plates. Waves throw the plates into the atmosphere, where they provide the seeds for clouds. One theme of this course is that life and the physical Earth are complexly intertwined. Life is a geological process.



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