Jim Bridger's Tall Tales
The other two authentic Bridger stories referring to the Yellowstone region are those concerning the stream-heated-by-friction and Hell-close-below. The former was recorded by Raynolds, while we are indebted to Ware for the latter. Several other tall tales concerned with the use of an echo as an alarm clock, the convenient suspension of gravity, and the shrinking ability of certain waters, have no traceable antecedents in fur trade days, and probably are of more recent origin.
from the National Park Service Links to the Past Site