What geologic time period/epoch do you find most interesting, and why?
The geologic time scale might seem confusing with all the different names and dates, but it is a really helpful way to think about Earth’s protracted history. Some of the names may already be familiar (like the Jurassic), but others might be a bit alien (like the Oligocene). The University of California Museum of Paleontology has a virtual “time machine” that allows you to explore Earth’s past online. Start on this page (Links to an external site.)Links to an external site. to learn more about the geologic time scale in general, and then go to this page (Links to an external site.)Links to an external site. to select a period and explore more. *Note: for the most current accepted dates for the boundaries on the geologic time scale, visit this page (Links to an external site.)Links to an external site.. Here are some important things that you should include in your post:
What is the name of the period or epoch that you have chosen?
At least three things that you find interesting or unusual about this time
At least one source in addition to the UCMP website where you obtained more information about the time that you selected
Be sure that your post is in your own words (read this page about Avoiding Plagiarism). Cite your references (for information on how to reference, check out the Purdue Online Writing Lab (Links to an external site.)Links to an external site.).
After you have posted your essay, you will be able to view the posts of other students. Comment on the posts of at least two other students. To receive full credit, your comments should be substantial (more than just one or two sentences, more than just something along the lines of “that’s interesting”).
Example post
I’ve selected the Miocene epoch, which began 23 million years ago and lasted until about 5.3 million years ago (Walker et al., 2018). I picked this time because there are beautiful outcrops of Miocene age rocks in Southern California, near the town of Barstow (The Desert Way, n.d.). Also, I conducted my PhD research in this area (Cole et al., 2005).
The climate of the Miocene was fairly warm (UCMP, 2011), and grasslands expanded in North America and Africa (Retallack, 2001) during this time. There were many interesting animals that lived in North America during the Miocene, including three-toed horses and pygmy rhinos (Hillinger, 1990), and kelp forests first appeared then (UCMP, 2011).
The image below from UCMP (Links to an external site.)Links to an external site. shows a fossil kelp from the Miocene Monterey Formation of California.
photo of kelp fossil
The images below are from a rock that I collected from the Barstow Formation, near Barstow, CA. The rock is called tufa, and it formed in an ancient lake. The image on the left is a normal photograph of the specimen. The image on the right is a “phosphor image” that shows areas of high radioactivity. This sample has a lot of uranium in it, which allowed me to use it for U-Pb dating (Cole et al., 2005).
rock from the Barstow Formation
Sources:
Cole, J.M., Rasbury, E. T., Hanson, G. N, Montanez, I. P., and Pedone, V. A. 2005. Using U-Pb ages of Miocene tufa for correlation in a terrestrial succession, Barstow Formation, California. Geological Society of America Bulletin 117(3/4): 276-287. https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/117/3-4/276/2146/using-u-pb-ages-of-miocene-tufa-for-correlation-in (Links to an external site.)Links to an external site.
Hillinger, C. (1990, January 15). Barstow’s Fossil-Rich Desert a Gold Mine for Students and Scientists. Los Angeles Times. Retrieved from http://articles.latimes.com/1990-01-15/news/mn-199_1_barstow-fossil-beds (Links to an external site.)Links to an external site.
Retallack, G.J. (2001) Cenozoic Expansion of Grasslands and Climatic Cooling. The Journal of Geology 109: 407–426. Retrieved from https://cpb-us-e1.wpmucdn.com/blogs.uoregon.edu/dist/d/3735/files/2013/07/grasslandscooling-ni1ucb.pdf (Links to an external site.)Links to an external site.
The Desert Way (n.d.) Rainbow Basin: A Coat of Many Colors. Retrieved from https://www.thedesertway.com/rainbow-basin-ca/ (Links to an external site.)Links to an external site.
UCMP (2011) The Miocene Ephoch. Retrieved from http://www.ucmp.berkeley.edu/tertiary/miocene.php (Links to an external site.)Links to an external site.
Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E. (2018) Geologic Time Scale v. 5.0: Geological Society of America, https://doi.org/10.1130/2018.CTS005R3C.