Okay, so we're wading into some rock mechanics with the intro class. One of the most important characteristics is how rocks respond to stress. If you've ever hit a rock with a hammer, you're probably aware of brittle behavior - where the rocks break into smaller pieces. If you've got the right kind of rocks (typically rocks under higher pressures and temperatures - like you see deep in the crust/mantle area) they might bend and flow. There are some other things that affect this brittle/ductile behavior. How quickly the stress is applied, for example. Hit the rock with a hammer and you might get broken pieces. Apply the same stress over a very long time and you might get the rock to bend.
This is rather hard to do with rocks, however. Silly Putty is a much more convenient material for those of us stuck on the earth's surface. Pull the silly putty slowly and it will stretch and flow. Pull on it quickly and you might get it to snap and break. Or, you could hit it with a hammer, which is not as easy as it sounds...
Wednesday, February 29, 2012
AW#43: Geological Illustrations
This month's accretionary wedge is hosted by "In the company of plants and rocks," which is a great title for a blog, BTW. The theme is "favorite geological illustration" and I've been having some trouble settling on one illustration. So I'm going to provide three.
This first illustration is not so much about the actual illustration, but the ideas it conveys. One of the great aspects of plate tectonic theory is that it explains so many different geological phenomena. It explains the patterns that we can observe and it allows for very powerful predictions regarding evidence (data, outcrops, etc) that we have yet to discover, and events that have yet to occur. This simple idea that certain parts of the earth's crust can be in motion relative to other parts of the crust was wildly revolutionary - it took many separate lines of evidence to pull together our current ideas regarding plate tectonics. Some 100 years ago when Wegner suggested continents plow through the ocean crust like giant icebreakers, he was criticized for lacking a mechanism to provide the necessary forces and allow for the crust to move. But today, we take this cross-sectional view of ocean crust subducting beneath continental crust as second nature. Yet just 50 years ago it would have been considered somewhat fancy and "cutting edge."
This second illustration is from my dissertation chapter about sedimentary patterns in the upper mississippi valley. If there's something other than a cross-section to get a geologist's blood going, it's a block diagram. It's like someone used a giant pie knife to carve out a block of the earth and hold it up for all to see. This particular diagram represents a great deal of sweat and tears on my part to finish my PhD.
This last example (one of my absolute favorites) is a cartoon my dad did for me right after I started working on my PhD. I think he found the idea of "Ice Age Land Snails" amusing in general. Because who wouldn't want to see giant land snails roaming the frozen tundra, attacking cavemen? I think the comment I like most is that he had a hard time making the radula (snail's rasping mouthparts) look threatening.
This first illustration is not so much about the actual illustration, but the ideas it conveys. One of the great aspects of plate tectonic theory is that it explains so many different geological phenomena. It explains the patterns that we can observe and it allows for very powerful predictions regarding evidence (data, outcrops, etc) that we have yet to discover, and events that have yet to occur. This simple idea that certain parts of the earth's crust can be in motion relative to other parts of the crust was wildly revolutionary - it took many separate lines of evidence to pull together our current ideas regarding plate tectonics. Some 100 years ago when Wegner suggested continents plow through the ocean crust like giant icebreakers, he was criticized for lacking a mechanism to provide the necessary forces and allow for the crust to move. But today, we take this cross-sectional view of ocean crust subducting beneath continental crust as second nature. Yet just 50 years ago it would have been considered somewhat fancy and "cutting edge."
This second illustration is from my dissertation chapter about sedimentary patterns in the upper mississippi valley. If there's something other than a cross-section to get a geologist's blood going, it's a block diagram. It's like someone used a giant pie knife to carve out a block of the earth and hold it up for all to see. This particular diagram represents a great deal of sweat and tears on my part to finish my PhD.
This last example (one of my absolute favorites) is a cartoon my dad did for me right after I started working on my PhD. I think he found the idea of "Ice Age Land Snails" amusing in general. Because who wouldn't want to see giant land snails roaming the frozen tundra, attacking cavemen? I think the comment I like most is that he had a hard time making the radula (snail's rasping mouthparts) look threatening.
Tuesday, February 28, 2012
Some more fluid-y stuff
Drop a steel ball with a hydrophobic coating into water and watch what happens:
Water is wet, part II
Trying out the Nanofabric in a slightly different way - getting a drop of water to roll down an incline.
Dropping a coin in water
Here's the deal: you want to drop a coin into a container of water. Maybe you're bored. Maybe you're trying to win a bet about hitting a submerged target. What's the best way to drop the coin so that you can hit that target? The easiest way is to drop the coin perfectly flat, with its faces parallel to the water's surface. Provided there aren't any currents or turbulence in the water column below, the coin should drop straight down.
Wednesday, February 22, 2012
An unexpected result
Popping water balloons is fun. But when I set up a water balloon to pop when it hit the top of an upward trajectory, I didn't expect the result I ended up with.
I really have no idea if I could replicate that or not. But you know I'm gonna try. I also tried a setup with the water balloon swinging from the side.
I really have no idea if I could replicate that or not. But you know I'm gonna try. I also tried a setup with the water balloon swinging from the side.
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