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 It is a bit outdated, but you will still see the range of studies within sedimentary geology, from the interface with chemistry (low-temperature diagenesis) to the combination of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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