National Geographic : 1962 Jul
charred trees on the volcano's slopes. These trunks were later buried by lava and pumice. It chanced in 1939 that a Civil ian Conservation Corps road crew unearthed bits of the charred trunks near Crater Lake Park. Mr. Guy R. Moore, a CCC educa tional adviser, was curious about the bits and saved some samples. Nineteen years later, in August, 1958, Mr. Moore read a NATIONAL GEOGRAPHIC article on carbon-14 dating, "How Old Is It?" by Ken neth F. Weaver and myself, de scribing a method developed by Dr. Willard F. Libby for fixing dates from such bits of organic matter. Mr. Moore sent me samples, and I submitted them through the Na tional Park Service to the United States Geological Survey. There Dr. Meyer Rubin and Mrs. Cor rinne Alexander ran painstaking tests. The answer: Mount Maza ma lost its peak between 6,400 and 6,900 years ago. Findings by Dr. Libby himself had already yielded similar dates-6,200 to 6,700 years in the past. The four figures average 6,550 years, placing Crater Lake's be ginnings at about 4600 B.C. In the following article, Mr. Walter Meayers Edwards of the NATION AL GEOGRAPHIC paints a striking portrait of Mazama's offspring as it is today. Lumps of charred wood date Mazama's eruption. At Char coal Point, 32 miles northwest of Crater Lake, Guy R. Moore examines remains of trees felled by fiery avalanches. Scientists, measuring radioactivity of sam ples he collected in the lake area, calculate the time of the eruption as about 4600 B.C . Llaos Hallway, a 200-foot deep gash that Whitehorse Creek cut through pumice, is named for an Indian deity. Glowing avalanches left the pumice. Hikers in the narrow ravine can touch both walls. KODACHROMES(C) N.G .S .