Andrew's Geology Blog

The Associated Press reports on a deadly "rockslide" that has killed dozens of people in Egypt. More exactly, it appears from the photos to be a rockfall, triggered as water from homes at the top of the rocky cliff near Cairo leaked into and weakened the strata there.

See more about the types of landslides.

Granite seems like a simple subject until you study geology. Then granite becomes a deep enigma and a stubborn controversy. But with this new article I hope to bring you the outlines of what granite signifies, not just why it's so popular for countertops. At the very least, you may take a little planetary pride, because granite is planet Earth's signature rock.
_{Salinian granite, King City Calif. — Geology Guide photo}

Classes have already started for a lot of students. Quick, grab yourself some cool wallpaper images for your laptop before someone notices how lame your default Windoze desktop is. (Professors and T.A.s, you too.) I just happen to have a bunch for you to choose from, in handy 800x600, 1024x768 and 1280x1024 sizes. And this just in—the newest batch of wallpapers, the Pebbles and Cobbles portfolio, features some images at 1600x1200 to serve the growing minority of people with that screen size.

These wallpapers are also good background images for presentations. You may make free use of them for desktops and presentations; any other uses fall under my fair use guidelines. I've seen them used in scientific posters at meetings, so I know they're good.
_{Rodeo Beach pebbles — Geology Guide photo}

A California entrepreneur wants to start turning straw into gold by bubbling power-plant fumes through seawater. Industry sources have written about it since 2007, but this month the the story reached Scientific American and, in a less rigorous treatment, the San Francisco Chronicle yesterday.

The process is designed to turn carbon dioxide from the power plant into carbonate in the seawater, which then combines with magnesium and calcium in the seawater to make unspecified carbonate compounds. But those compounds aren't cement, and they can't be turned into cement without driving off at least some of the carbon. So something very important is missing, because the inventor of the process, Stanford prof Brent Constantz, claims that his process pulls half its weight worth of CO₂ from the atmosphere. More precisely, half of the product's mass would be carbon and oxygen in 1-to-2 proportion. Such a material is not cement; it's filler.

Other blogs have written about this, and nobody understands what Constantz is claiming. Add me to them. But Constantz is not a lightweight and deeply understands carbonates as well as how living things deal with them. He may have a secret biocatalyst in the patent-pending process. His firm, Calera, is apparently named after the local Paleocene limestone unit, which crops out in Morgan Hill and Daly City and elsewhere in the Santa Cruz Mountains.

I see a possible waste problem. Bubbling clean flue gas through seawater won't exactly pollute it, but it will charge the water with carbonic acid. This is a major, underappreciated risk associated with CO₂ emissions generally—high CO₂ upsets seawater chemistry so that corals and shellfish and plankton can't build shells. Returning large quantities of carbonated seawater to the ocean will basically bypass the atmosphere and mainline CO₂ directly into the planet's bloodstream. On the other hand, reporters say that heat in the flue gases dries up the water. That's a LOT of water—and what about the salt? Salt is death to concrete.

Basics of Cement and Concrete

Thanks to Kris Hirst, the About.com Archaeology Guide, for finding the presentations from the Pecos Conference about the hypothesis that a cosmic impact at about 12,000 years ago wrought worldwide havoc. I've touched on it previously; see here and here for background. The Pecos Conference was held from 7 to 10 August in Flagstaff, Arizona. Kris's post points to a YouTube playlist with video of a two-hour presentation on 8 August and a long panel discussion on 9 August. This is cutting-edge, mostly unpublished science presented in an informal setting. Treat it with an appropriate level of enjoyment and skepticism.

The independent ScienceDebate2008 campaign launched in December (with my early endorsement) as a way to force the presidential candidates to talk about important matters. Finally, candidate Obama has responded to the campaign's 14-item questionnaire, and McCain has promised his own response as well.

Obama proposes to double research funding in basic physical and life science in 10 years; promote science teaching with grants and academies; make the R&D tax credit permanent; renew DARPA; expand USGS, NOAA and NSF marine research; re-establish the National Aeronautics and Space Council; revitalize NASA; establish a national Chief Technology Officer; and lots more, much of which is already familiar.

Check it out.

Today is so hot that I feel like I'm in Las Vegas. And that's a good thing because Las Vegas is such a splendid place for anyone excited by geology. If you're headed there and want more than glitz during your stay, start here for an introduction to Las Vegas geology. Links go out to maps and photo tours as well as visitor information.
_{Valley of Fire State Park — Geology Guide photo}

Recently I've come upon the remarkable stone serpentinite in some widely separated places: in the woods of Vermont, along the Calaveras fault in California, and on the face of a building in my home town. This specimen is from the second locality and shows the peculiar "mineral" called bastite—pyroxene crystals transformed to serpentine pseudocrysts. See the others just before this one in the Serpentinite Gallery.
_{Bastite in serpentinite — Geology Guide photo}

As all eyes are on Denver this week, I would be remiss not to mention some of the geological attractions of that excellent city (whose mayor, John Hickenlooper, is a geologist into his third career). Delegates and press people, if you have a day to spare, I urge you to tour the Golden area just west of town along the Front Range. Among the attractions are Dinosaur Ridge, Red Rocks Park, the Triceratops Trail, and a host of other sights to see. Even though the Democrats will miss the chance to nominate a geologist for office this year, I hope the visitors to Denver can take in some Rocky Mountain rocks.
_{Castle Rock overlooks the town of Golden — Geology Guide photo}

I used to live near New York City. One day in 1965, the ground shuddered and my mother immediately told me, "That's an earthquake." Sure enough, it was, but the experts couldn't say much about it. Today we've learned much more, and East Coast seismologists talk about features like the Ramapo Seismic Zone and the 125th Street fault—names that may sound unsettling in this unexpected role. A new study in the Bulletin of the Seismological Society of America sums up the historical and geologic data and concludes that damaging earthquakes around New York City are more likely than we used to think. The press release for this paper quotes coauthor John Armbruster: "Today, with so many more buildings and people, a magnitude 5 centered below the city would be extremely attention-getting. We'd see billions in damage, with some brick buildings falling. People would probably be killed." One prime quake target: the Indian Point nuclear power complex in Peekskill.