Stalagmites pinpoint drying of American West
All around the deserts of Utah, Nevada, southern Oregon, and eastern California, ancient shorelines line the hillsides above dry valley floors, like bathtub rings — remnants of the lakes once found throughout the region. Even as the ice sheets retreated at the end of the last ice age, 12,000 years ago, the region remained much wetter than it is today. The earliest settlers of the region are likely to have encountered a verdant landscape of springs and wetlands. So just when and why did today’s desert West dry out? Researchers from MIT and elsewhere have now determined that the western U.S. — a region including Nevada, Utah, Oregon, and parts of California — was a rather damp setting until approximately 8,200 years ago, when the region began to dry out, eventually assuming the arid environments we see today. The team identified this climatic turning point after analyzing stalagmites from a cave in Great...