Planet Earth

Conference Report: Breaking News From the World of Geology

By Kathy A SvitilNov 13, 2003 6:00 AM


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Last week, thousands of geoscientists from around the world converged on Seattle, Washington, for the 115th annual meeting of the Geological Society of America. The conference featured the requisite sessions on sediments and seismology, but it wasn’t just a rock fest—session topics included the geology of salmon, high-tech ocean observatories, the origin of life, and the peopling of the New World. Among the highlights:

Soils make the god: Geologist Gregory Retallack of the University of Oregon studied the soils around 40 ancient temple sites and concluded that the classical Greek gods and goddesses arose, quite literally, from the earth. He found a striking correspondence between the type of soil where a particular deity was worshipped and the personality or attributes of that god. For example, the temples of Aphrodite and Poseidon, deities associated with the sea, were built on dry desert soils. Because such soil was unsuitable for farming, the local inhabitants would have looked to the sea for sustenance. On the other hand, the temples of Demeter, the goddess of the harvest, and Dionysus, the god of vineyards, were associated with a fertile grassland soil called xeralf. Sites sacred to Hades and Persephone, the god and goddess of the underworld, had bare, inhospitable rock at the surface. In contrast, the temples of Athena (the chief god of the city of Athens) and Zeus (“the big boss,” Retallack says) were built on land that had been thoroughly reworked by its inhabitants. “It had a lot of human junk, which indicates a long human occupation. It was city soil,” Retallack says. “This research supports the idea that religion is a form of multiculturalism, with fishermen, for example, having a different religious system from the agriculturalists.”

Global warming is good for the grapes: Gregory Jones of Southern Oregon University and his colleagues looked at the climate and vintage-quality records of the world’s top 27 wine-growing regions—including the United States, Europe, Australia, South Africa, and Chile—and compared them with wine ratings from the Sotheby’s vintage-quality scale. The result: Although average temperatures in those regions have risen by four degrees over the past 50 years, so, too, have vintage ratings. Better winemaking techniques have played a large role in raising wine quality, but warmer weather and more consistent temperatures in traditionally cool regions might also be beneficial to grapes and other crops. Still, Jones cautions that future warming—another 4 degree increase is predicted for wine-growing regions over the next 50 years—might not have a such positive effect. It could improve fruit ripening in cool growing regions, but vineyards in areas that are already warm could face water stress, overripe fruit, and more pests and disease.

Mars’s massive ripples: Thirty years ago, images of Mars from NASA’s Viking probes revealed the presence of sand dunes and sand ripples, long parallel lines that form when grains are pushed by water or wind. Data from the workhorse Mars Global Surveyor, currently orbiting Mars, show that the dunes can rise up to 300 feet above the surrounding surface, twice as tall as their terrestrial counterparts. The ripples atop the dunes are just as impressive—20 feet high or more—reports Kevin Williams of the Smithsonian National Air and Space Museum, who used high-resolution stereo images from the Global Surveyor’s Mars Orbiter Camera to survey the sand structures. Researchers have not yet determined exactly how the dunes and ripples are sculptured. They suspect the impressive height of these features is due to the Red Planet’s low gravity, one-third that of Earth, which allows dust and sand grains to stack up into much higher piles before their weight sends them crashing down.

Hardy Midwestern microbes: The world’s most alkaline life-forms have been discovered living in an iron-slag dump in southeastern Chicago. George Roadcap of the University of Illinois and his colleagues uncovered the microorganisms while studying groundwater in the Lake Calumet region, which has been contaminated by more than 100 years of iron-slag dumping from steel mills. Genetic studies revealed 140 unique types of microbe, including cousins of bacteria previously found in the highly alkaline waters of Mono Lake, California, and deep gold mines in South Africa. The water at the dump site had an alkalinity of pH 12.8, about the same as that of a common floor-stripping chemical. Roadcap hopes to learn whether the microbes were somehow imported to the site or whether they are local populations that adapted over the past century to the increasingly toxic conditions.

Feathers reveal the secret life of birds: Scientists know far more about what birds do while nesting, when the animals are easy to spot and observe, than when they are in the air on long-distance migrations. Satellite tracking of birds is expensive; banding them is cheap, but the banded animals rarely turn up, so it takes years to accumulate accurate data about their dispersal patterns. Jason Duxbury of the University of Alberta described a cheaper and more efficient method: looking at the chemical composition of feathers. Depending on environmental factors such as rainfall and temperature, the water, soil, and plants in different parts of the country have varying concentrations of the isotopes of carbon, oxygen, hydrogen, and nitrogen. Because birds, like all organisms, are built from these elements, the ratios of these isotopes get imprinted in their feathers, leaving behind a chemical printout of where the animal has been. Duxbury took advantage of this isotopic record to monitor the movements of peregrine falcons and burrowing owls, birds that are rarely recaptured in banding studies but regularly leave discarded feathers in their wake. The isotope analysis traced peregrine falcons wintering in Texas back to nesting grounds in Canada and showed that burrowing owls that breed in Canada also spend their winters in southern Texas and central Mexico.

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