It is difficult to construct an interesting page on stratigraphy. So many lecture outlines, so few useful pages. The Geology and Geological Time page of the University of California, Berkeley, is not bad as an introduction, especially for those of you with just one previous geology course. You can always practice your stratigraphic skills with this elaborate dating assignment you can download and then cut into little cards. (I wouldn’t bother, but maybe you have a roommate with little to do?) Visit Jurassic Tank, an experimental stratigraphy apparatus at the University of Minnesota. This detailed website on the geology of the south-central coast of England is also a very good example of stratigraphy in action (and where I had many students doing fieldwork years ago). For the lab, you can’t beat these brief descriptions and images of sedimentary structures from Wikipedia.
Here is your Essay #1 assignment.
Wadi sediments in Death Valley, California. (Click to enlarge)
Geology in the News –
Earth’s oldest rock was apparently found on the Moon by Apollo 14 astronauts. It is about 4.1 billion years old and was blasted off the Earth by a giant impact. You know there’s a good story here.
The famous 79 CE eruption of Mount Vesuvius apparently turned an unfortunate man’s brain to glass. I can’t tell exactly how this happened, but there is a skull with a supposedly vitrified brain. Obsidian, I suppose.
How can I make sedimentary dynamics, at least the statistical parts, interesting? The Web doesn’t help much. We could learn a bit about Sir George Gabriel Stokes (1819-1903) of Stokes’ Law. Most of the web material, though, consists of calculating pages for the Reynolds Number and the Froude Number, and the details of the Bernoulli Effect and Hjulstrom’s Diagram. Fortunately the US Government has livened things up a bit with a series of Quicktime movies of sedimentary bedforms in action, along with more than you want to know about bedform classes. This is a very nice presentation — you have many viewing choices. The USGS also provides downloadable code and software for simulating ripple and dune bedforms and crossbedding. We’ll have more pretty pictures and movies when we begin studying particular sedimentary environments.
Time to begin thinking about your research project for your paper. We’ll talk about your ideas in lab. Please download the list of 2020 Potential Research Paper Topics and the included form to turn in to me during your lab this week.
Here is a blog post I wrote on our glorious Ro-Tap sieving shaker system.
Sediment plume from DeGeerladen, south shore of Isfjorden, Svalbard, Norway. (Click image for larger view.)
Geology in the News –
“The Universe Is Disappearing, And There’s Nothing We Can Do To Stop It.” A dramatic headline that is certainly true. This is a good article in Forbes discussing modern ideas of cosmology. The future looks very cold and dark, but at least it is a long time from now!
Can this be true? One-quarter of Americans don’t know the Earth orbits the Sun. I hope most of these people are just trolling the poll.
Stardust older than the Solar System found in the ever-so-useful Murchison Meteorite. At least 7 billion years old.
A thorough understanding of geologic time is fundamental in any geology course, and it is especially critical in Sedimentology & Stratigraphy. Because time scales change, I will hand out in class (as part of your first lab) our version of the Geological Time Scale. You will see that I recognize the Ediacaran Period before the Cambrian, and the Paleogene and Neogene instead of the old Tertiary. Remember that geologists make a crucial distinction between relative and absolute time, which is usually calculated radiometrically. Radiocarbon dating is a special case of radiometric dating. (Note that I’m a fan of Wikipedia. If an article there is inaccurate, we can fix it!)
Here’s a page that you may use often this semester: Internet Resources for Sedimentary Geologists (with only a few annoying dead links). It is a bit outdated, but you will still see the range of studies within sedimentary geology, from the interface with chemistry (low-temperature diagenesis) to the combination of sediments and biology (ichnology), along with plate tectonics, radiometric dating, sequence stratigraphy, and paleoenvironmental interpretations.
Our lectures and labs on the fabrics and textures of sediments and sedimentary rocks are not thrilling, although I’ll work hard on them! Here’s a clever graphic for the Udden-Wentworth grain-size scale. The Wikipedia page on grain sizes is very good. (And if it wasn’t, we’d make sure to fix it!)
Middle Triassic marginal marine sequence, southwestern Utah. (Click for larger view.)
Geology in the News —
This interactive tectonic globe is super cool. Try it!
Here is an excellent essay on Nazi geological and cosmological nonsense. “World Ice Theory also had the ideological advantage over other border sciences in that it was almost perfectly compatible with a Nazi cosmology.”