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Petroglyphs


This week volunteers who want to help the BLM protect ancient native American rock art gathered in St George Utah. One of the presentations was by a Nevadan who has discovered an innovative way to date the art. Ky Plaskon reports.

PLASKON: Farryl Lytle grew up 200 miles north of Las Vegas outside of Pioche in Eagle Valley. He had always known about petroglyphs, but not much about the two dimensional figures that appeared to be no more than scribbling in the rock. Then he went off to be a scientist and for decades he worked as a Boeing materials engineer in Seattle. When he returned to Eagle Valley 12 years ago to retire he still had the same questions about the mysterious petroglyph.

LYTLE: How old are they, who made them?

PLASKON: All scientists know is the Anasazi and Freemont Native Americans lived in this area until about 700 years ago, and then they disappeared from the acheological record in the midst of a drought. One of the most well known remnants of the culture are the petroglyphs. But the rock art's age could range in the tens of thousands of years. Lytle thought he might be able to apply his materials engineering knowledge to determine their age by studying what's called the desert varnish.

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LYTLE: The native American pecked away the desert varnish to make their designs visible and when they did that they cleared off the old desert varnish and so the clock started then.

PLASKON: The desert varnish slowly grows back over the petroglyph after the Native American chipped it away. By measuring the amount of varnish currently on the rock and calculating the rate the desert varnish grows, Lytle says he can estimate how old these petroglyphs are.

LYTLE: It's a thousand, plus or minus 200 years.

KAFFMAN: That's impressive, wow I am not sure.

PLASKON: Viki Kaffman Assistant professor of Anthropology at UNLV says scientific methods to date including carbon dating and weathering haven't been that accurate. Anthropologists have looked at the desert varnish, but not the way Lytle has. The brownish varnish on the rock is left by microbes that eat dust. By using a 30-thousand dollar Niton Portable X-ray Fluorescence Machine he bought himself he can measure manganese and iron deposits the microbes leave behind over thousands of years. Lytles discovery may be useful to tell scientists about life beyond even earth.

KELLIHER: We contacted him because one of the hottest things to determinie is an instrument to determine if there has ever been life on Mars.

PLASKON: Warran Kelliher is a senior researcher with NASA and was in charge of the determining components of soil samples on Mars during the Viking Mission to that planet.

KELLIHER: There has been or may be continuing life on mars if we find the same sort of desert varnish on the rocks that we see on mars and from preliminary indications there are some increased manganese deposits on these rocks on Mars.

PLASKON: So Kelliher, Lytle and the University of Texas teamed up to present a three-quarter million dollar proposal for Lytle to study the deposits in Nevada for three years. The idea is to use the study to compare rocks in Nevada with rocks on Mars, looking for signs of the microbes dead or alive. Kelliher says it usually takes 6 months to get an answer from headquarters but the proposal was submitted to NASA more than a year ago. Kelliher thinks burocracy may be getting in the way of the project but he remains optimistic.

Ky Plaskon, News 88-9 KNPR

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