AUSABLE CHASM, a gorge of scenic and scientific inter est situated in the north-eastern part of the State of New York, U.S.A. At this point, which is about midway in its course from the Adirondack mountains to Lake Champlain, the Ausable river has worn in hard sandstone a series of narrow zigzag chasms, the whole about 2m. long and in places 17 5 f t. deep. The rocks forming the precipitous walls are of Potsdam formation and pre sent an instructive display of fault lines and displacements.