Wednesday, February 07, 2007

Drown in your Pattern life!

Enough ranting and raving! Back to some great geology.

One of the things I really like about geology are rocks that when you take pictures of them look like they'd make a really non-threatening desktop background on your computer. There are patterns in rocks that just kind of have a look about them - they just look interesting. Not only do they look cool, but most patterns in rocks are very diagnostic in helping you imagine the geologic history of that rock, or groups of rock.

I love sedimentary structures; structures that formed when the sediments within the rock were laid down. There's so much there.

Take for example this picture:

These are some ripple marks within a Tertiary-aged rock unit in central Idaho. Ripples are great indicators of where the sediments where deposited, in this case near a lake-shore. the wavelength and amplitude of measured ripple marks can tell you not only the water velocity at the time they were made, but also the direction of the water movement and even the water depth. Combined, you can paint a pretty vivid picture of earth's past just by looking at these patterns.

Here's a picture of a sand dune close up. eolian sands are so well sorted, just their perfect uniformity looks cool I think.

(the best part about the above picture is that if you print it out, rubber cement it to the back of a shadow box, add some colored seashells from petsmart's hermit crab section, and sell them at a Southern flea-market you can make $10's of dollars!)

Awesome picture of some pitted and chemically eroded Dolostone from a trip I took into mammoth cave. I think this picture turned out really neat for some reason. I had a student hold a flashlight up to this rock and then snapped a picture! the pitting is actually related to the bedding within the rock.

Converse to well-sorted sediments; we have a project site my company is working on in Utah, on top of a terminal moraine, where the sorting of the grains is so perfectly poor, it almost looks fake. This is kind of a bad picture, but look at the sediment in here. There's almost an equal share of every grain size in every portion of the exposed sediments.

Like if you grabbed a bucket of this stuff, sorted it all out according to its grain size, you'd have an equal volume of sand-sized stuff to an equal amount of boulders. It seems really fucking boring at first, but in nature its actually VERY difficult to have a large grain size distribution like this. There's no other force on earth, not oceans, not rivers, not lakes, not wind that will leave sediments like this, only glaciers. ...Well if you ever look underneath the table after a marathon Old-Country Buffet session, sometimes you can get a glipse of this phenomena amongst the biscuit crumbs and gravy.

its not just sedimentary rocks, like check out this picture of lava. it just looks cool. the vesicles, the color...just looks neat. rokz R sw3et!

And finally, one of the coolest looking rocks on the planet: the Banded Iron Formation in Northern Minnesota. I used to take students to this very outcrop every year. The layers are sedimentary layers of iron oxide minerals and quartz sandstone. they've been all compressed and squished in the eons following their deposition. cool shit.

....Am I crazy here? just re-reading this post makes me feel like a complete and total dork. I'm not sure what's nerdier, the fact that I look at rocks a lot and think about the patterns, and it appeals to me enough to take pictures of them, or the fact that I felt good enough about the pictures as to share them on this website (or ahem, that I have alot of pictures like this!).

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