Triassic Haunting
The ancient geological and celestial past speaks to us in strange and unanticipated ways.There's a generally-accepted theory that the age of dinosaurs became ancient history as a result of a giant meteorite shower, or one vast meteor hitting earth and whose impact on the surface of the earth threw up a dense curtain of debris into the atmosphere where the sun's rays were unable to penetrate and life on earth degraded, then disappeared, until the dense debris cloud finally dissipated.
Now comes a new study into the earth's geological past, led by Matt Leybourne, an New Zealand geoscientist and two colleagues at the Geological Survey of Canada, claiming that shocked, fractured and melted rocks around an ancient impact site in central Manitoba caused by the crash of another, much earlier meteororite, allowed the mineral fluoride to leach into the area's groundwater.
"It's a smoking gun that's been smoking for a long time", said Jan Peter, one of the study's co-authors. Elevated levels of fluoride represent a major health issue to humans, exposed to them, having the potential to cause damage to teeth, softening of bones, calcified tendons and ligaments, and neurological damage, according to the study.
The North American practise of adding fluoride in discrete amounts to municipal drinking water has long been hailed as an antidote to the prevalence of tooth decay particularly among vulnerable children whose diet is often compromised by the too-frequent consumption of sugary drinks and candies. With its introduction decades ago, the incidence of tooth decay in the general population fell substantially.
Most producers of toothpaste routinely add fluoride to their products to ensure additional tooth-enamel protection. Yet a space rock that hurtled through the upper atmosphere - to breach our earthly atmosphere and finally smash into our globe - landing in Canada over 200-million years ago, unleashed fluoride into groundwater now imperilling the health of several communities in Manitoba.
The research group studied the quality of the groundwater around the ancient Lake St.Martin meteorite crater, north of Winnipeg. Finding greatly elevated levels of fluoride and other chemicals in the area's groundwater, and linking that to the shattering of subsurface granite represented a first in associating a meteorite impact to the disturbing of the earth's crust, leading to groundwater contamination.
The wonder of it: An extraterrestrial object of gigantic dimensions upsetting the stability of earth's geology, a quarter of a billion years ago in time and space. Well before the tentative stirrings of primitive life-forms on this planet.
The resulting 24-kilometre-wide crater is evidence of that truly earth-shattering event. And there are other identified sites similar in creation and ancient lineage to this one. In fact possibly creations of a similar celestial body, fragmenting on entering earth's atmosphere. Craters in France, Quebec, North Dakota and Russia, created within hours of one another when huge fragments of a meteor struck earth.
All this came to light because Canadian scientists have been grappling for years with the issue of poor water quality in the town of Gypsumville (named after gypsum deposits found there). Along with two closely co-located First Nations communities around Lake St. Martin, where it was well known that inordinately elevated levels of fluoride existed, polluting the water table, and forcing residents to look for alternate, safe water sources.
Now, at last, and at the very least, the mystery has been solved.
Labels: Canada, Environment, Science
posted by Pieface @ Tuesday, January 29, 2008
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