Scientific American: Toward the end of World War II, the U.S. Navy began mapping an area of northern Alaska extending south from the Arctic Sea across the North Slope and down to the forested valleys south of the Brooks Range. In an effort lasting a number of years, surveyors flew low in a small plane, snapping thousands of photographs with a large-format K-18 camera pointed out the craft’s open door. About 10 years ago, Matthew Sturm of the U.S. Army Corps of Engineers and his colleagues obtained the …