The bristlecone pines of California's White Mountains are some of Earth's oldest living things. The ancient trees -- at least one over 4,700 years old -- live in an otherwise barren environment. Cold and dry conditions limit the growth of bristlecones, and annual variations in temperature and precipitation are recorded in their growth rings. These rings ../Features/Paleoclimatology_CloseUp/ form a record of past climate conditions. Scientists use the rings to reconstruct the climate history of the area. Bristlecone pine tree-ring records, derived from living and dead wood, extend back roughly 8,900 years. This image shows part of Schulman Grove, the location of the oldest bristlecones yet found (with the exception of www.terrain.org/essays/14/cohen.htm one older tree found in Nevada in the early 1960s). It was acquired by Space Imaging's Ikonos satellite on May 25, 2003. The access road and visitor center for the grove are visible in the upper-left hand corner. The Methuselah Walk, named for the grove's oldest inhabitant, begins at the visitor center and winds up and down through the oldest trees at an elevation of about 2,800 meters (9,200 feet). Individual trees, several of them over 4,000 years old, are visible as dark spots in the image. Virtually all of the bristlecones live on beige dolomite soil, which bristlecones prefer to the surrounding brown granite soil. Trees on north-facing slopes grow faster and more densely than those on south-facing slopes due to the longer persistence of snow on the northern slopes. Patches of snow are still visible in this late-spring image.