Terrestrial Sedimentary Systems (February 4 & 6)

This week we continue our discussion of the sedimentology of desert systems. (You’ll have to just endure my enthusiasm for deserts.) To fully sample my joy, I simply must link you to the Wooster Geologists blog entries for our field trips to the Mojave Desert. You may also want to see posts from our geological field trips in the Negev Desert of southern Israel. There are some other more spectacular desert geology websites. Start with the USGS page set on the geology and resources of deserts. The Great Sand Dunes National Monument also has superb geology sections, as does Death Valley National Park. Here is a nice site for Space Shuttle photographs of the Atacama Desert in Chile. The DesertUSA commercial site will introduce you to other desert pages and images.

Let’s take a moment to remember, as we will in class, a geological and military hero: Ralph Bagnold. He was a pioneering geologist, particularly in deserts. He was also a significant contributor to the Allied victory over the Italians and Germans in North Africa during World War II.

For fluvial systems, here is the Wikipedia page on alluvium (note links within to other specific pages). Here’s a video of a flash flood in southern Utah. (Don’t mess with flash floods!) Here’s another with a drone perspective. Note that people don’t drown as much in flash floods as they get pummeled to death by debris. Be safe out there. As for meandering rivers, here is a spectacular series of LiDAR images of past Mississippi River channels.

NASA has an extraordinary website called “The Visible Earth“. It is a diverse and large set of satellite and Space Shuttle images of the Earth’s surface, all searchable. Look for views of deserts from space.

Please note again the Earth Sciences Department Writing Page, the link to which is always on the right side of this page.

Finally, Test #1 will be on Thursday, February 13. As a sample of what to expect, here is a pdf of the 2019 first Sed Strat test. We will not have covered all the same topics, so some questions in that test are on material we may not do this year.

Sand from Kelso Sand Dunes, Mojave Desert, California. (Click to enlarge.)

Geology in the News –

We live in an anti-science age in which scientists and scientific ideas have lost considerable credibility with the public. Here is an interesting take on why we should not call this a “war on science”as so many do. Such aggressive language usually has a negative effect on audiences. What we should do to restore respect for the scientific method and discourse is unclear.

This BBC article on the Thwaites Glacier in Antarctica is fantastic, especially the images and graphics. This is where Dr. Alley did her recent field work. It is a very dramatic place of high consequences. Here’s an accompanying video.

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Principles of Stratigraphy — Introduction (January 28 & 30)

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.

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Sediments and Sedimentary Processes II (January 21 & 23)

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.

This website will be helpful this week: The Math You Need.

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.

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Sediments and Sedimentary Processes I (January 14 & 16)

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.”

 

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