By Sid Perkins
A volleyball-sized stalagmite taken from a cave in northern China has given scientists insight about how the region’s precipitation has varied — and possibly influenced the rise and fall of various dynasties — for the past 1,800 years.
Researchers collected the telltale formation about 1 kilometer inside Wanxiang Cave, which lies along the eastern edge of the Tibetan Plateau. In recent years the area has received an average annual precipitation of 48 centimeters, with about 80 percent of that falling during the May-to-September monsoon season.
But rainfall amounts have varied significantly from year to year in recent centuries, says Larry Edwards, a paleoclimatologist at the University of Minnesota in Minneapolis. He and his colleagues analyzed an 11.8-centimeter-long section of the stalagmite and report their results in the Nov. 7 Science.