It is difficult for anyone standing on the brink of the Chasm, after having seen the placid flow of the Zambesi above the Falls, to believe that the fissure into which the river is so suddenly precipitated has been formed gradually by the action of the river itself, and not by some great convulsion during which the very crust of the earth was rent. The narrowness of the abyss, the strange zigzags along which the tumultuous waters rush after their first great plunge, the mystery which has long surrounded the further course of the river after it swings away out of sight among its forbidding precipices, and the knowledge that the rocks across which it plunges are of volcanic origin, are all factors that have aided the illusion. Hence it is not surprising to find that the explanation given by David Livingstone half a century ago, that the majestic Zambesi has here been intercepted by a rent due to some earth movement in the solid rocks, has been adopted without question in all the later descriptions of this wonderful spectacle.