[Aztlan] Sun ended Chinese dynasties, Mayan classic?

[ECOLING at aol.com]

The current issue of _Science_ (vol.322, 2008 Nov. 7)
has a lead article on p.837 titled

"Chinese Cave Speaks of a Fickle Sun Brining Down Ancient Dynasties"

"A 1.2-meter-long chunk of stalagmite from a cave in northern China
recorded the waning of Asian monsoon rains that helped bring down 
the Tang dynasty in 907 C.E."

The key was an "a really, really clean sample" --
a stalagmite with relatively high amounts of uranium and exceptionally
low clay-borne thorium, so they dcould do uranium-thorium
radiometric dating of layered deposits to within an average of just 2.5 years 
...

and

"Comparing their rain record with Chinese historical records,
Zhang and colleagues found that three of the five
multicentury dynasties during that time -- the Tang, the Yuan, and the Ming 
-- 
ended after several decades of abruptly weaker and drier summer monsoons, 
possibly poor rice harvests, and social turmoil."

The article mentioned the "collapse of Maya civilization" and
the advance of glaciers in the Alps.

The method is explained in a longer technical article on pp.940-942

"A Test of Climate, Sun, and Culture Relationships 
from an 1810-year Chinese Cave Record"

Best wishes,

Lloyd Anderson
Ecological Linguistics
PO Box 15156
Washington DC 20003
ecoling at aol.com
202-547-7683



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