People have known for a long time that you can date the age of a tree by its rings. A tree grows one ring a year and they vary in size according to how suitable for growth the climate was that year. Between 1939-1953 a dendrologist named Dr. Schulman focused on aging conifers in the lower forest zones, such as piñon and Douglas Fir. He did not include the longer records of the Giant Sequoia because of the semi-humid region they grow in where floods and seepage can skew their ring records. Then he learned that certain species of trees in the upper-forest zones, growing under stressful conditions, showed sensitive records of drought in their growth-ring sequences. The short, distorted and dwarfed trees of the upper tree lines were now his focus. He discovered a Douglas Fir 600 years old in Mesa Verde National Park, Colorado, an 800 year old bristlecone on Mt. Evans in Nevada, and a 975 year old piñon pine in Utah. With all this data, a picture of past climatic events began to emerge.
In 1953, Schulman found a limber pine in Sun Valley, Idaho, with 1,700 growth rings. Then he made a detour to map the White Mountains acting on a rumor that old trees existed there. Here he found a multiple-stemmed bristlecone 36 feet in circumference that had been named "Patriarch" by a local ranger. After taking samples, he found it to be only 1500 years old with typical ring growth of the upper tree line. But at this point he knew that the bristlecones were better recorders of drought conditions than the limber pines. Even more exciting were the old trees found nearby on even drier sites.
These trees showed large areas of deadwood and thin strips of living bark. Most trees need bark around their whole trunk, but these trees make do with little bits here and there. The trees growing in the most extreme conditions, with little soil and moisture, seemed to be the oldest. Several trees in the 3,000 to 4,000+ year range were discovered in this area. In 1957 "Methuselah" was found to be 4,723 years old and remains today the world's oldest known living tree.
A tried-and-true method to calculate the age of carbon based matter was with carbon dating. But scientists began to suspect that their measurements were off and the data that Dr. Schulman had recorded with his trees verified this error, adding 1,000 years to the date of the construction of Stonehenge, for example. It also disrupted the theory anthropologists had regarding the beginnings of man. The theory that Mesopotamia was the cradle of civilization and all mankind wandered off from this central location, was disproved when varied sites where early humans had lived were dated as equally old. The wooden effects Native Americans left behind contained rings which could be matched to the rings of verified trees and that's how we know when these sites were occupied. The ring comparison charts reminded me of the way scientists look for DNA matches with the spacing between the dark lines.
Today we drove into the White Mountains to see the old bristle cones. Ken loves to photograph gnarly trees and these were the best. It was astonishing to see a dead looking tree with a thin piece of bark remaining that was nourishing a vibrant, living branch. We studied the trees carefully, trying to figure out whether they were dead or alive. In many cases, both appeared to be true. Those that still had lots of sap oozing over their cones, displayed the sharp bristles that give these trees their name. In this area the trees grow thickest in the calcium-rich dolomite soil, not because the trees prefer it, but because other plants can't grow there and compete for light and water. Location, location, location.
The drive to the mountain top was challenging. It was full of switch backs and paved until about 10,000' where the visitor center and Schulman Grove were located. The drive to the Patriarch Grove was twelve miles farther on unpaved, unimproved road . If you want to know if this drive was worth the hour it took each way, you will get a different answer depending on which of us you ask. Near the top on an especially steep and narrow stretch, we encountered a large car going the other way. There was absolutely nowhere to pull off to the side. I don't know how Ken was able to see out of our back window because the car was covered with a thick layer of dust, but somehow he reversed our course much to the gratitude of the other car and his white-knuckled wife.