"Indeed, Congress explicitly stated that ???no Federal lands shall be designated as ???wilderness areas' except as provided for in [the Wilderness Act] or by a subsequent Act.??? Id. ?? 1131(a).The Act defines ???wilderness??? as ???an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain,??? as well as ???an area of undeveloped Fe" . . . .