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High and Dried

Christine Chen examines stony deposits called tufas on an ancient lakeshore in the central Andes Mountains, northern Chile. Chen, a graduate student in the MIT-WHOI Joint Program, visited there in 2015 to study the dry lakes, once rain-fed, for clues to the area’s past climate and water balance. The tufas are fossilized remnants of algal reefs that formed concentric “bathtub rings” as the lake shores receded some tens of thousands of years ago. Back in the lab, Chen analyzes the tufas’ composition to determine when the reefs lived and when the lakes, lacking rain, shrank and disappeared. (Photo courtesy of Christine Chen, Woods Hole Oceanographic Institution)