Labels: art, books, colorado, indiana, louisiana, maps, michigan, new mexico

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

This image came to my attention the other day via Lutz's Geoberg blog. It's one of the high-res images provided by the newly-launched satellite, the GeoEye-1, which is supplying new images to Google*. The image shows a marginal lake associated with an alpine glacier in Kenai Fjords National Park, Alaska (just south of Seward):


The top of the above image is not north; it's southwest. Mentally rotate it, and you can see that the resolution is a lot better than the current level on Google Earth and Google Maps:


The thing that struck me about the new GeoEye image, aside from its beauty, is the distinct pattern of iceberg sizes in the lake: freshly calved off the glacier, the biggest icebergs are close to their source, while further away the icebergs are smaller. This pattern struck me as being analogous to sediment. Fresh from its source, sedimentary particles are at their largest size, and the further away they travel, the more weathering they experience. This weathering (in particular of the physical variety) tends to break them down into smaller pieces. Adjacent to an orogenic belt, for instance, you tend to find deposition of sedimentary particles shed off the uplifting mountains. As a general rule, these are of the largest sizes and the greatest volume closest to the source, and then particle size and stratum thickness both diminish with increasing distance from the orogen.

For a North American example, consider the Catskill Clastic Wedge, a tick pile of sediments shed off the late Devonian Acadian Orogeny along the east coast. Here's a cross-sectional view** (pre-Alleghany Orogeny deformation) of the wedge, running from the Bay of Fundy west to Michigan:


Same pattern! Coarse stuff, and more volume of stuff, close to the source. Finer stuff, and less volume of stuff, further from the source. Just like the iceberg, except the weathering of the icebergs is mainly thermal, while the weathering of the sediments is physical, accompanied by depositional sorting by the transporting currents of water.

__________________________________

* An original version of this post misidentified Google as the owners of the GeoEye-1, as opposed to the company called GeoEye, which sells images to Google. Thanks to Bruce Haley for the correction. (updated 8:14AM eastern time on Dec. 9, 2008)
** Image redrawn (by me) from an original in Prothero & Dott (2003).

Labels: alaska, analogies, art, canada, glacial landforms, glaciation, maine, michigan, mountains, new york, satellite imagery, sediment

My friend Casey went to Michigan last weekend to hang out with her sisters, and one thing they did was go snowshoeing/sledding at the YMCA camp where they all grew up. When they walked out to the lake, an interesting sight awaited them: a scum of ice balls floating in the water, and (presumably pushed by the wind), collected up along the shore. She brought back some photos.


It's a neat phenomenon, and I'm not really too sure what to make of it. The question is: are these concentrically zoned features, like oolites, hailstones, or the hematite concretions seen in Friday's post? Or are they fragments of lake ice that got broken up and then rounded due to abrasion and jostling against one another in the waves? I'm guessing that the first hypothesis is correct, but unfortunately I don't have any way to test it from here in DC.


Some observations: the ice balls are pretty well sorted, pretty spherical, and well rounded. The ice balls are packed closer together closer to the shore. There also seems to be a size gradient from larger ice balls close to shore (right, in the image below) to smaller ice balls out into the open water of the lake (left, in the image below). If this isn't just a trick of the camera's perspective, could this correspond to increased growth due to closer packing (and thus more time lifted up out of the water into the cold Michigan air) close to the shore?

Finally, I note that in some areas, multiple ice balls have clumped together into a larger entity, as some oolites will do. This cohesion between ice balls is potentially the first step for making a solid layer of ice that will extend out from the shore over the whole lake.

Anyone else ever seen anything like this? What's going on?

Labels: ice, lakes, michigan