Scientists at the New Mexico Office of Archaeological Studies use a Low Energy Plasma Radiocarbon Sampling device on a sample of gelatin at its lab near Santa Fe.
The machine is used to date artifacts by doing minimal damage to the sample. — The contraption he built looks a little like something you might see from “The Nutty Professor.”But Marvin Rowe is no nut.
Most of them that I’ve encountered are inorganic pigments and that’s where the importance of the small sample comes in.”Blinman adds that, under the best of circumstances, standard radiocarbon dating requires 30 milligrams of carbon.
Rock art pigments don’t have that much carbon in them.
Carbon-14 is also passed onto the animals that eat those plants.
After death the amount of carbon-14 in the organic specimen decreases very regularly as the molecules decay.
Radiocarbon decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food.
Radiocarbon present in molecules of atmospheric carbon dioxide enters the biological carbon cycle: it is absorbed from the air by green plants and then passed on to animals through the food chain.
(Eddie Moore/Albuquerque Journal)Marvin Rowe, a scientist at the New Mexico Office of Archaeological Studies, adjusts the Low Energy Plasma Radiocarbon Sampling device he built to date artifacts with minimal damage. That machine he built, and what it’s used for, helped Rowe win the prestigious Fryxell Award for Interdisciplinary Research from the Society of American Archeology two years ago.“We call the process Low Energy Plasma Radiocarbon Sampling,” said New Mexico’s state archeologist Eric Blinman, who credits Rowe with inventing the process.
“But a lot of people just refer to this as ‘Marvin’s Machine.'”The process is important because, unlike other methods of radiocarbon dating that destroy the sample being tested, LEPRS preserves it.
“But we now have the ability to date incredibly small amounts of carbon – 40-100 millionths of a gram – and that is the real revolutionary aspect of this.
And the ancillary part of that is it’s non-destructive.”That’s important to Nancy Akins, a research associate with the Office of Archaeological Studies, who in February was having a bison tooth and sheep bone tested by “Marvin’s Machine.” The items were excavated from the site of a rock shelter in Coyote Canyon north of Mora.“It could be 500 years old or it could be 5,000 years old,” she said of the bison tooth, the result allowing her to complete her report of the site that she’s determined to have been used by humans as a hunting outpost starting 1,700 years ago.“I’m just waiting on the dates, because it’ll change everything if we get dates where I can actually say, ‘OK, that’s what the sheep bones date to and that’s what the bison dates to.’ It tells us an awful lot about how they were using the land on the east side of the Sangre de Cristos.”Because a lot of that part of New Mexico is private property or under land grants, such finds as the one in Coyote Canyon are rare, she said.“Unless there’s a road or something, we don’t have any information at all.
Carbon-14 has a half-life of 5,730 ± 40 years—, half the amount of the radioisotope present at any given time will undergo spontaneous disintegration during the succeeding 5,730 years.