National Geographic : 1921 Sep
246 THE NATIONAL GEOGRAPHIC MAGAZINE Photograph by Frank I. Jones FUMIAROLES IN FRONT OF BAK;1l) MOUNTAIN CAMP\ Photograph by R. E . Ilelt ONE OF TIHE MANY CRATERS IN THIE SAND-FLOW The presence of these craters is evidence that explosions occurred after the general body of the hot sand-flow had come to rest. The whole surface of the east arm of the valley is pitted with craters like this. Many of them are the seats of vigorous fumaroles.