Not all areas of the Tibetan Plateau rose at the same time, according to researchers who are determining the past elevation of plateau locations by studying the remains of terrestrial plants that once grew there.
"The Tibetan Plateau is responsible for the monsoons in India," says Dr. Pratigya J. Polissar, postdoctoral fellow in geosciences, Penn State. "People have documented ecological changes around the edge of the plateau that may indicate when it was high, but we do not really know when the plateau rose and so we do not know when the monsoon circulation began."