Skip to comments.Volcanic destruction? Not always
Posted on 12/05/2011 7:31:04 AM PST by SunkenCiv
Archaeologists long believed the volcano changed Sinagua culture. Yet because the date of the eruption remained elusive, they could not tell how fast those changes occurred.
Ort, however, had a geological clock that let him make a better estimate. The Earth's magnetic north pole constantly drifts. Researchers have records of drift going back thousands of years made by measuring how certain minerals are magnetized to align with the magnetic poles as they settle in lake sediments.
What Ort needed was a way to link these paleomagnetic measurements to the age of artifacts found in villages abandoned after the eruption. Ort chose minerals in hearths because they become demagnetized when they heat up and realign when they cool. They would provide the date of their last use. By matching their alignment with known magnetic fields, Ort narrowed the time of the eruption to 1050-1100 A.D.
Researchers further narrowed the date by studying tree rings for strontium, an element trees absorb from the fallen debris of an eruption. The trees near Sunset Crater showed a strontium spike in year 1085.
Pinning the date of the eruption showed that changes happened quickly after the volcano erupted. The most visible change occurred in agricultural practices. The volcano deposited a layer of ash and small cinders over a large area. They acted as a mulch to keep rainfall from evaporating.
"The Sinagua might have seen that lots of plants -- big plants -- were growing in areas with mulch, and moved there," Elson said. They soon learned to manage the cinders to farm flat lands that were previously too dry to grow crops.
(Excerpt) Read more at physorg.com ...
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
To all -- please ping me to other topics which are appropriate for the GGG list.
Hence the expression, “Go with the flow.”
Love that area . . . my BA degree stomping grounds.
But but but but central planning is always better!
but Othuga and the globalist oligarchy are addcited to central planning!
That physorg.com website is really neat. I found a bunch of articles on subjects I like.
Question: Any problems creating an account if you're not already a 'scientist' or student?
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