school of geology repudiate, nay, try as far as possible to 'shut their eyes to the frequent occurrence of such dislocations. Let us now, however, test the erosion theory by an examination of the phenomena attending the two greatest cataracts in the world. In them, beyond doubt, we see the power of running water exercised to its fullest extent. The first, NIAGARA, is appealed to triumphantly as an undoubted proof of the effects of running water. "We have here," Sir Charles Lyell assures us, a river which has been eating its way backwards through the rocks for a distance of 7 miles." Fortunately he himself furnishes the explanation of this: "The St. Lawrence flows over a bed of limestone 90 feet thick, beneath which lie soft shales of equal thickness, continually undermined by the action of the spray. driven violently by gusts of wind against the base of the precipice. In consequence of this action, and that of the frost, the shale disintegrates and crumbles away, and portions of the incumbent rock overhang 40 feet, and often when unsupported tumble down." Is it not singular that the author should not have perceived that this explanation refutes his own theory? The hard limestone bed, 90 feet thick, of the St. Lawrence, is not eaten back by the current flowing over it. It suffers no detriment from the passing river, but breaks away by its own weight,1 because its natural support is removed, not by the running stream above but by the splash of the spray wafted up from below the Falls, which dissolves the soft shale. To use the words of Professor Tyndall, “the most violent whirling of the shattered liquid (!)" and "the most powerful eddies recoiling against the shale." But for the accident of the occurrence of this shale the Falls would not have altered their position. So far from the limestone bed being eroded, it is by its resistance to the river alone that the shale has not all been removed long ago, and the cataract demolished. The retrocession of Niagara Falls, therefore, is not the result of river erosion; it is not even caused by contact with running water, but by the fortuitous concurrence of a soft stratum soluble in water, whether still or in motion, at a considerable depth below the bed of the river. The great cataract of the Zambesi, in Central Africa, called by its discoverer, Livingstone, the Vic 1 The famous Table Rock at Niagara, a part of the 90 feet limestone, projected, it is stated, 70 feet beyond the face of the cliff before it broke by its own weight; but for many years before that event occurred the river had ceased to flow over it. F toria Falls, redresses the balance of glory for the Old World in possessing a larger and grander waterfall than any in the New. in the New. But besides that, it furnishes an undoubted example, on the largest scale, of a river-bed made for the river and not by it. This commanding stream having attained a width of more than a mile, flowing from N. to S. along an undulating plain bounded by distant hills, on a sudden drops down into a crack stretching directly across its course, forming a trough 350 feet deep, but not more than 80 feet wide, into which the whole body of water is discharged. The Fall is twice as high and twice as wide as Niagara, but differs from it in that, immediately opposite to the Fall, rise three successive natural walls of rock of the same height as that over which the river leaps, separated from one another by narrow rifts. These triple barriers consist of wedge-shaped promontories of rock with vertical sides, projecting alternately from the right bank and from the leftlike side-scenes in a theatre, but entirely overlapping one another. Out of the first deep trough the river, after its descent, is compelled to find its way through a gap only 80 yards wide in the first opposing rock wall. A second wall here confronts it, by which the stream is turned at an acute angle to the right. It is next forced round the second promontory, then |