gravels, and sands, still lying undisturbed ill the ancient beds; 2. The system of profound canons from 2,000 to 5,000 feet deep, which score the flanks of the great mountain-chains, and form such a fascinating object of study, and not less of wonder, because the gorges were altogether carved out since the beginning of the glacial period; 3. The modern rivers, mere echoes of their parent streams of the early quaternary age. As between these three the early quaternary rivers stand out as vastly the most powerful and extensive. The present rivers are utterly incapable, with infinite time, to perform the work of glacial torrents. So, too, the Pliocene streams, although of very great volume, were powerless to wear their way down into solid rocks thousands of feet at the rapid rate of the early quaternary floods. Between these three systems of rivers is all the difference which separates a modern (uniformitarian) stream and a terrible catastrophic engine, the expression of a climate in which struggle for existence must have been something absolutely inconceivable when considered from the water precipitations, floods, torrents, and erosions, of to-day. "Uniformitarians are fond of saying that give our present rivers time, plenty of time, and they can perform the feats of the past. It is mere nonsense in the case of the cañons of the Cordilleras. They could never have been carved by the pygmy rivers of this climate to the end of infinite time. And, as if the sections and profiles of the canons were not enough to convince the most skeptical student, there are left hundreds of dry river-beds, within whose broad valleys, flanked by old steep banks, and eloquent with proofs of once-powerful streams, there is not water enough to quench the thirst even of a uniformitarian. Those extinct rivers, dead of drought, in connection with the great canon system, present perfectly overwhelming evidence that the general deposition of aërial water, the consequent floods and torrents, forming, as they all do, the distinct expression of a sharply-defined cycle of climate, as compared either with the water phenomena of the immediately preceding Pliocene age, or with our own succeeding condition, constitute an age of water-catastrophe whose destructive power we only now begin distantly to suspect."