Scientists have discovered a site containing the most extensive evidence seen so far in Mexico for the Clovis culture. The find extends the range of America’s oldest identifiable culture, which roamed North America about 13,000 years ago. Read the full story on Nature News here.

A newly discovered crater on Mercury may have been geologically active as recently as a billion years ago. Read the full story on Nature News here.

Posted on behalf of Rex Dalton

The oldest dwelling structure in Utah — dated to 3,000 years ago — was reported this week, offering a glimpse of ancient life in the Great Salt Lake Basin.

The pit house structure was located near a river bed in the highly developed Salt Lake City region after a team of scientists persevered for years to study the location without project funding. Some now fear the potentially important site may be lost to development, with but a plaque to mark the location.

In a lecture at the annual meeting of the Geological Society of America, Kathleen Nicoll of the University of Utah in Salt Lake described enlisting students from local elementary and high schools to help survey the site’s rich artifacts. "It is easier to get on the Oprah Winfrey Show than to get funding for this type of work,” says Nicoll.

Such dwellings across the United States are drawing scrutiny as researchers employ more widely available sophisticated techniques to test pollen, bones and artifacts to answer questions about paleoenvironments and inhabitants. “This is a very important time for understanding the transition to agriculture in the Southwest, when people became more sedentary,” says Nicoll.

The location is between the Jordan River and a Denver & Rio Grande Railroad right-of-way, which is now eyed as a route for a light-rail transit system.

In the 1990s, the pit house was identified during an environmental survey for construction of a prison. When that plan faded, the site — across the river from a golf course — was also eyed as a possible housing development. And some residents want a park. What becomes of the location will be determined by this three-way debate.

Nicoll said radiocarbon dates from within the pit house and adjacent sediments found repeated occupations from 1,500 to 3,000 years ago.

Remnants of the pit house were found just a few centimeters below the surface, after surveys of the terrace identified 30,000 artifacts within an area of nearly 40 hectares. “I found that sixth grade students are very good at counting artifacts,” says Nicoll.

In the future, the team plans to study plant or artifact samples to learn more about the diet of the people of the time.

Some of the oldest dwellings in the West have been located in valleys east of the Sierra Nevada Mountains in California and in Colorado.

Mark Stiger of Western State College in Gunnison, Colorado, and David Meltzer of Southern Methodist University in Dallas have studies underway on multiple dwellings. One mountain camp site may date to the age of the Folsom people, about 10,400 years ago, Stiger noted

Nicoll’s study is under peer review at the journal Catena.

Posted on behalf of Rex Dalton

The fast-sinking idea that a comet struck North America 13,000 years ago, killing off the Clovis Paleo-Indians and triggering the Younger Dryas cold snap, was again undermined by geochemical tests released this week.

A US-Belgium team has reported that it can find no evidence of a comet impact at seven sites and in sediments in two ocean cores corresponding to when the object reportedly exploded over the North American ice sheet. Francois Paquay, a doctoral student at the University of Hawaii in Honolulu, reported the team’s results at the annual meeting of the Geological Society of America in Portland, Oregon.

There was no rise in iridium at the Clovis sites, no change in other platinum group element levels that would be altered by an impact, and no concurrent iridium rise in cores from the Guaymas Basin in the Gulf of California and the Caribbean Sea south of Tortuga, he said.

“There is nothing; there was no impact,” says Paquay, whose co-authors are Philip Claeys, a prominent researcher on impacts at the Free University of Brussels, and Greg Ravizza of Hawaii.

Findings from the study are at the heart of an article now under peer review at the Proceedings of the National Academy of Sciences.

Earlier this month, PNAS published a study by researchers led by Todd Surovell of the University of Wyoming at Laramie; they were unable to find the abundant levels of magnetic spherules purported to be remnants of the explosion.

Proponents of the comet theory insist their idea has validity. One author of the original theory, Richard Firestone of the Lawrence Berkeley Laboratory in California, wrote in an email: “The authors of the recent papers that found nothing have an agenda to disprove our work and to keep anyone else from publishing positive results. This and the previous paper are examples of sloppy research.”

But among those who study extraterrestrial impacts, there is little support for the theory. The GSA report is likely to only accelerate the level of criticism.

For instance, Paquay found in examining the ratios of isotopes of osmium, a platinum group element, there was no change at the studied sites. And there was no change in the examined levels of the cores, drilled years ago as part of the Integrated Ocean Drilling Program. All the study results were confirmed in two independent laboratories, Paquay added.