Geological Quote of the Week - Writing

Although not from the geology literature, and not even from the a scientific journal, I feel this quote applies to anyone who has written a book or a journal article (just replace "book" with "Journal Article", or something similar).

"'I never thought, when I used to read books, what work it was to write them.'

'It's work enough to read them, sometimes,' I returned."

Dickens, C. 1850. David Copperfield. p.891

And as always you can check out my other Geological Quotes at my website HERE.

Geology of the National Parks Through Pictures - Grand Canyon

My next post about the Geology of the National Parks Through Pictures is...

You can find more Geology of the National Parks Through Pictures as well as my Geological State Symbols Across America series at my website Dinojim.com.

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Grand Canyon National Park

 The entrance sign. (A favorite thing of mine to photograph)

 This is our first view of the canyon. We went during the middle of March. Not a good time to go apparently.

 But it did eventually clear up. This is a similar location as the previous picture on a subsequent day.

 Some elk by our hotel room.

 View off into the canyon. The canyon began to be formed due to plate tectonics. There used to be a subduction zone off the western coast of California (where the San Andreas Fault is now). The plate that was subducted, the Farallon Plate, was forced down underneath North America. This plate was hot and therefore force the North American Plate upwards. The upward push of the plate was counteracted by the Colorado River eroding down through the plate. The upward motion of the plate allowed the river to erode downward faster and deeper than it otherwise would have.

The rock units that were eroded through range in age from fairly recent to over a billion years old. The types of rocks are limestones, sandstones, shales, as well as several metamorphic and igneous rocks. The result is a huge range of bright colors represented in the canyon.

 Here I am trying to get a vertical view of the canyon.

 Here is a panoramic view of the canyon.

The cloud formations across the surface here made the landscape really look pretty.

 Along the rim they have these markers designating the passage of geologic time. I walked all the way back to the beginning to get the first one.

A cool train station within the park. 

Another panoramic of the canyon.

What are ... Varves?

The next entry in my What are Wednesdays series is to discuss varves (First entry here). I ran into this problem when I was teaching Petrology where the students either A) Didn't know what a varve was, or B) Didn't understand how it formed.

Varves from the Green River Formation used as framing in the Geology building at the University of Utah

Varves, as pictured above, are sedimentary features that alternate in color from light to dark, often in thin bands. Some of the most famous varves are found from the Green River Formation of Wyoming and surrounding regions. The Sutton Geology building here at the University of Utah uses a lot of the Green River Formation both for framing materials but also as wall decorations so it was fairly easy to get a picture of some nice varves.

Varves are formed in end glacial lakes. The lakes has a seasonality, where they freeze every winter and are defrosted every summer. What happens is that during the summer sediment run off from the melting glacial is allowed to settle on the bottom of the lake. This produces the light colors which is rich in quartz sand and other sand and silt grains. You can often find drop stones in this layer as well (like that seen in the lower left corner) where a larger grain gets stuck in ice. The ice chunk floats out into the lake and then melts, dropping the larger grains.

During the winter the lake freezes over. The freezing of the lake limits all sediment from entering the lake so no more large sediment grains are deposited on the lake bottom. What does happen though, is that the freezing of the lake kills much of the biological activity that is occurring in the lake and settles the currents in the lake. The settling of the currents allows for finer grained materials and the organic material to settle to the bottom. These are the darker layers.

So each year of a varve is represented by one couplet of bands: 1 light for summer and 1 dark for winter.

That is all I have to say on varves. If you have any questions feel free to ask and if there are any topics you would like me to present on What are Wednesdays let me know.

CBS Sunday Morning - Hunting for Meteorites

A nice piece was played this morning on CBS Sunday Morning discussing the Russian Meteor of yesterday and linking it to the meteorite hunting that goes on in Antarctica. They mention that the meteorite hunting was little known, but I thought it was common knowledge. I guess that is part of the problem of being so in to geology that I don't realize what other people don't know.

 

Or go here if the video doesn't seem to be working:

http://www.cbsnews.com/8301-3445_162-57569765/meteorites-hunting-missiles-from-outer-space/

 

(but it does take a minute or 2 to load).

Geological Quote of the Week - Shocking

The background on this quote is that the authors were trying to get a group of fish to swim in a school using electrical shocks.

By thus time it was clear that the punishment of the mild electric shock was causing an association to be established. The association made by the fishes at this time was definite and distinct but not at all of the nature anticipated. At this time the reaction was for either or both fish to rush at the other and to bite at its fellow. These fish lack jaw teeth and are evidently unable to inflict any considerable injury. They can exhaust one another, however, by such attacks. Thus by the time about fifty shocks had been administered, one of the fish was rather badly beaten and doubtless would have died if the experiment had been continued.

Besides being rather cruel, I thought it was hilarious that the side effect of the shocks would turn the fish against each other instead of making them swim together. Turns out the fish assumed the other fish was the one causing the shocks, hence the attacks.

Breder, C.M., Jr., & Halpern, F., 1946, Innate and Acquired Behavior Affecting the Aggregation of Fishes: Physiological Zoology, v. 19, p. 154-190.


And as always you can check out my other Geological Quotes at my website HERE.