RAIN AND RIVERS. CHAPTER I. LYELL'S FOUR CONTRADICTORY THEORIES OF FORMING VALLEYS. LYELL HAS RETROGRADED FROM SOUND TO UNSOUND DOCTRINES. 6 trograded from sound doc LYELL writes of Werner: When sound opinions Lyell has rehad thus for twenty years (fifty centuries) prevailed sound to unin Europe (the world), . . . Werner (Lyell), by trines. his simple dictum, caused a retrograde movement, and not only overturned the true theory but substituted for it one of the most unphilosophical that can be well imagined.' B Lyell's own particular theory of the formation of valleys. In reference to the theory that valleys are formed by rain and rivers,' these words of Lyell are true of himself as I have altered them. There is, perhaps, no creed of man which, like this, can be traced up to the most remote antiquity, and traced down from the most remote antiquity to the present day. Lyell has himself quoted Pythagoras for it, through the medium of Ovid: Eluvie mons est deductus in æquor. Quodque fuit campus vallem decursus aquarum But Pythagoras only enunciates the doctrine of Eastern antiquity; that is, of the Egyptians, the Chaldæans, and the Hindoos. But since Pythagoras introduced this doctrine in the West, if it has ever slumbered, it has been perpetually reoriginated. Lyell shows that among the Greeks it was taught by Aristotle; among the Romans by Strabo; among the Saracens by Avicenna; in Italy by Moro, Generelli, and Targioni; and in England by Ray, Hutton, and Playfair. In contradiction, however, to these authorities, ancient and modern,—in contradiction, as I think, to common sense, and in contradiction to three other theories which he himself uses,-Lyell has started a theory of his own in reference to the formation of valleys. He conceives, that as land has been slowly raised through the sea and above it by subterranean heat, the waves and currents of the sea have formed the valleys. 6 In the second edition of the Tree-lifter,' I answered, That the action of waves on land slowly emerging from the deep should have a tendency to wash away soft parts and to leave hard parts, I can conceive; but to attribute the formation of our valleys to this cause, is to suppose that the materials of all the valleys running from the tops of all the heights on the globe were originally softer than the materials of the intervening ridges; but in almost all cases we can see that this is not so, by the corresponding strata on the opposite sides of valleys. In regard to currents: a current might decapitate a continent as it rose, supposing equal softness of materials, or it might scoop a horizontal groove of any size or depth, or (granting lines of hard intervening ridges) many grooves. But they must all be horizontal, and in one direction. No marine current could make a single channel sloping from a height to the sea; still less the myriads on myriads of dry upper valleys which ramify in all directions, from all river valleys, through and to all sides of the tops of all elevations, whether high or low. The sea ends every valley, but it never yet Origin of allubegan one. That is, when the river has done its vial plains. utmost, it is the sea which prevents the farther deepening of the valley. But as the denudation. and deepening of the inclined upper parts continue, the lower part of the valley becomes horizontal. The passage of the detritus of the upper parts is then checked in this horizontal part, and soil accumulates there backward up the valley. This is the origin of alluvial plains, which I have never seen an attempt to account for. They seem, by common consent, to be omitted in all theories of the formation of valleys. Alluvial plains are, however, frequent features over the globe, and most important features. Yet neither the formation of any of them nor the present and perpetual daily growth of each of them, can be accounted for except by the principles which I advocate. And instead of the sea forming valleys in the land, valleys often form land in the sea, that is, deltas; and, as the sea by checking the longitudinal rush of rivers allows this deposit of land forward in it, the sea may thus be said to assist in prolonging valleys. 6 Bottle off the sea' and all estuaries, and their valleys will be deepened; for the tidal part of each river will be a torrent on the brow of a mountain. In this case deltas and alluviums would disappear; but they would not go with a run,' or by the direct action of rivers. Rivers would only cut |