Inyo National Forest: Methuselah Walk and the Science of Reading Time in Wood

Edmund Schulman was a scientist at the University of Arizona's Laboratory of Tree-Ring Research when he drove to the White Mountains in the late nineteen forties and started taking core samples from bristlecone pines. He was looking for old trees. What he found was a science he had not anticipated.

Dendrochronology, the reading of time from tree rings, had been established as a discipline in the early twentieth century. Each ring represents one year's growth, wider in good years with more moisture, narrower in drought years. But the record only extended as far back as the oldest trees scientists had sampled. The bristlecones in the White Mountains pushed that record back thousands of years, past any living tree previously studied. Because dead bristlecone wood persists in the dry high-altitude environment without rotting for additional thousands of years, researchers found they could build a continuous ring-width record extending back almost nine thousand years, overlapping the rings of living trees with those of long-dead specimens. That record became one of the primary calibration tools for radiocarbon dating, allowing scientists to correct for variations in atmospheric carbon fourteen that otherwise would have introduced errors into dates assigned to ancient materials worldwide.

This means that the oldest trees in the Inyo National Forest are not merely botanical curiosities. They are instruments of precision science. The understanding of ancient climate patterns, the calibration of archaeological dates from Egypt and the Middle East, the reconstruction of drought sequences across the American Southwest, all of these rest partly on samples taken from trees standing in this cold dry air above ten thousand feet.

Schulman published his work in National Geographic in nineteen fifty-eight. He died before the issue was printed.