Yesterday, I asked you to figure out what I was getting at here:


The answer is that I was trying to depict the fundamental difference between the two different classes of glacial landforms by showing the two different actions glaciers can take on rock: either they can carve it up, or they can carry it off a ways and dump it.


Glacial landforms may be broadly grouped into erosional landforms (like cirques, aretes, horns, and hanging valleys) and depositional landforms (such as moraines, eskers, drumlins, and kettles). Erosional landforms dominate in areas of alpine glaciation (like, say, the Patagonian Andes). Depositional landforms dominate in areas of continental glaciation (like, say, Wisconsin).

If any educators want a full-size (i.e. PowerPoint-ready) version of this image, shoot me an e-mail. I'll send you one, and I won't do so at a glacial pace.

Nobody really guessed it. But there were some great guesses regardless, and perhaps the big lesson is that the Analogy Is In The Eye Of The Beholder. Thanks to all who contributed ideas to the discussion!

Labels: analogies, art, contest, geomorphology, glacial landforms, glaciation, graphics, patagonia, wisconsin

Nevada's Yucca Mountain site for a proposed nuclear waste repository has lost much of its funding in President Obama's proposed budget. Personally, I think this is a good call - I never thought that the Yucca Mountain site seemed viable for the geological long-term. For a facility being designed to outlast human civilization (warning signs are not written in English, but in sign language that's predicted to still be useful when potential meddlers show up 10,000 years from now), Yucca Mountain is located in too tectonically-active an area for my liking. Basin and Range extension, with associated earthquakes and volcanism, imperils the facility's security over the long-term.

But then where do we put this nuclear waste? We've got more and more of it every day. I'm a fan of nuclear energy because I feel that in spite of the risks associated with radioactive leaks, it's a proven technology that looks better all the time because it produces no carbon emissions. To me, the relatively short-term (local) risk of radiation leaks is outweighed by CO2's long-term (global) risk of climate change. Provided sufficient security, I think it's a great "halfway house" between fossil fuels and 'alternative' energies like solar, wind, and geothermal.

Yucca Mountain has several advantages in terms of its location: it's dry, and it's not in someone's backyard (far from large populations -- though Los Vegas residents might quibble with the definition of "far"). But Nevada's regular seismic shaking (3rd in rank among the U.S. states, after California and Alaska) and the proximity of some young volcanic extrusions make me think it's not so great a spot if you want the waste to stay put. I'm thinking that the best place for nuclear waste would be in the craton, the stable interior of the continent. I'm thinking: Canadian Shield, maybe in Minnesota or Michigan or Wisconsin. The issue there is water: you would be trading tectonic stability for saturation and precipitation.

I'll readily admit I'm not an expert here -- just a geologist speculating on an issue that's more complex than mere geology. What do you think? Where's the best place to store nuclear waste until radioactive decay makes it reasonably safe? Use 10,000 years as your hypothetical timeline, bearing in mind how different the world is today than it was 10,000 years ago.

Labels: CO2, earthquakes, energy, environmental, michigan, minnesota, nevada, volcano, wisconsin