ash 6655.9o Louis J. Sheehan, Esquire

Louis J. Sheehan, Esquire. Scientists now have geochemical clues about the composition of volcanic ash used in Maya pottery between the 7th and 10th centuries, though the ash’s source is still a mystery. Results of a new study definitively discount one Mexican volcano, long thought to be the likely supplier of the ash.http://Louis2J2Sheehan2Esquire.US

Researchers have long known that Maya of the Late Classic period, an archeological interval that stretched approximately from 600 to 900, used a mixture of volcanic ash and clay to make pottery. http://Louis2J2Sheehan2Esquire.US Microscopic analyses of broken potsherds show that the ash particles are sharp-edged, indicating they were freshly erupted when the pots were made, says Brianne Catlin, a geoarchaeologist now at Hess Corp. in Houston. While at the University of California, Santa Barbara, she and her colleagues analyzed pottery fragments found at El Pilar, a Maya site near the Belize-Guatemala border, in an attempt to find the source of the pottery’s ash.

Very little soil covers the carbonate bedrock at El Pilar, and all of the ash layers found there are too old and chemically degraded to have supplied the ash used in the pottery, Catlin reported Monday in Houston at the annual meeting of the Geological Society of America. Because the Maya pottery typically is both heavy and fragile, it’s unlikely that such items were imported. Instead, she speculates, ash was hauled in for local potters from other areas at great effort — especially considering the Maya had no roads, no pack animals and would have needed to import several tons of the material each year to produce enough everyday dishes and pottery for the site’s thousands of residents.

To see how various combinations of temperature and heating times affected the chemical composition of ash in pottery, Catlin and her colleagues fired pots using a 50-50 mixture of clay from the El Pilar site and volcanic ash of known chemical composition from California. In the tests, for example, the longer the pottery was fired, the more sodium was driven from the material. The hotter the firing temperature, the higher the calcium concentration became. Finally, the firing process didn’t affect the silica content of the pottery at all, Catlin notes.

The ash in the potsherds found at El Pilar is about 78 percent silica, the researchers found. That’s distinctly different than the composition of ash from El Chichón volcano, which lies about 375 kilometers west of El Pilar and spews ash that’s about 58 percent silica. Some archaeologists have suggested that material lofted from El Chichón was used in the Maya pottery, because an ash plume from a 1982 eruption wafted eastward and fell on El Pilar, but the new results don’t support that notion, says Catlin.

She and her colleagues are now analyzing ash from several volcanoes that lie between 350 and 400 kilometers southwest of El Pilar, to see if material spewed from those peaks has a chemical composition that matches the ash used in the Maya pottery. Besides being about 78 percent silica, that ash probably had a 0.4 percent concentration of calcium, the team’s tests suggest.Louis J. Sheehan, Esquire

mammals 8833.43.9 Louis J. Sheehan, Esquire

Louis J. Sheehan, Esquire. Between a fifth and a generous third of the world’s mammal species now face the threat of extinction, according to the first comprehensive review since 1996. http://louis-j-sheehan.biz

Now 1,139 species rank in the most imperiled categories, the conservation monitoring organization IUCN reported October 6 at its World Conservation Congress in Barcelona, Spain. http://louis-j-sheehan.biz

Data from more than 1,700 experts went into this five-year review of the conservation status of all known wild mammals for the IUCN Red List of Threatened Species, the main global scorecard for extinction risk. http://louis-j-sheehan.biz

“All in all, a major event,” says Don Wilson, a mammal curator at the Smithsonian Institution in Washington, D.C. He has read a summary of the IUCN results to be published in Science October 10, and calls the study “by far the most extensive” analysis of mammal status so far.

IUCN reviewed mammals in 1996, but the world has changed since then, says one of the leaders of the effort, conservation ecologist Jan Schipper, who works with IUCN and Conservation International. Tasmanian devils, for example, have shifted from the category of least concern into the endangered category. Their population shrank some 60 percent during the last decade as a lethal, infectious face cancer spread through the species. And shrinking wetlands in Asia pushed the fishing cat out of a vulnerable ranking and into the endangered category.

Assessment methods have changed too. Taxonomy based on DNA has split some of the species listed in 1996 and lumped together others. Category definitions have changed too, but IUCN is working on a comparison between the new and the old reports, Schipper says.

“One of the things that surprised me the most was that there are still 836 species that are data-deficient,” Schipper says. Biologists may know mammals relatively well compared to other animal groups, but hundreds of mammals still remain so mysterious that the IUCN group couldn’t assess their conservation status.

If those mystery species are doing just fine, a situation Schipper considers improbable, then 21 percent of the currently known 5,487 mammal species face a serious threat of extinction. If all the little-known species turn out to be faltering, then that’s 36 percent of known mammals in trouble.

“We don’t want to say, ‘the sky is falling,’” Schipper says. The IUCN sets out quantitative criteria for the tally’s three worrisome categories of animals threatened with extinction: critically endangered, endangered and vulnerable. Even the least threatened among these, the vulnerable species, meet one of several thresholds, such as losing more than a third of their population during either a decade or over three generations.

In the new review, habitat loss or degradation ranks as the most widespread threat, grinding down the populations of some 40 percent of species studied. Hunting for food or medicinal use affects 17 percent of mammal species, the researchers say.

Mammals in the seas face a particularly troubled time, with about a third of the status-known species at risk of extinction. Their biggest problem is accidental death, such as dying in fishing gear set for other species or colliding with boats.

Not all the news is bad. Since the last assessment, reintroduction programs have moved black-footed ferrets from “extinct in the wild” to critically endangered — a step in the right direction.

“We have all known for a long time that things were not going well for threatened and endangered species,” Wilson says. But it’s “sobering indeed” to have such a massive effort document that more than a thousand species could disappear unless trends change.

Another Smithsonian mammal curator, Richard Thorington, says, “I am not greatly surprised, although the figures are higher than I had expected.”

Schipper says he hopes the report will inspire people to reduce their ecological footprints in their everyday lives, from grocery shopping to transportation, and to “just go out and get some face time with animals.”

This was only a report on wild species, he adds. Homo sapiens isn’t included, but IUCN does rank it — in the least threatened category. Louis J. Sheehan, Esquire