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When we see a mound of earth or a bank of clay worn into miniature mountain-chains and canons and gulches by the rains of a season, we do not doubt our eyes; we know the rains did it. But when we see the same thing copied in a broad landscape, or on the face of a state or a continent, we find it hard to believe the evidence of our own senses. The scale upon which it is done, and the time involved, put it so far beyond the sphere of our experience that something in us, probably the practical, everyday man, refuses to be convinced.

The lay mind can hardly have any adequate conception of the part erosion, the simple weathering of the rocks, has played in shaping our landscapes, and in preparing the earth for the abode of man. The changes in the surface of the land in one’s lifetime, or even in the historic period, are so slight that the tales the geologists tell us are incredible.

When, during a recent trip through the great Southwest, I saw the earth laid open by erosion as I had never before dreamed of, especially when I visited those halls of the gods, the Grand Canon and Yosemite Valley, I found my capacity to believe in the erosive power of water and the weather quite overtaxed. It must be true, I said, what the geologists tell us, that water and air did all this; but while you look and wait, and while generations before you have looked and waited, all is as quiet and passive as if the slumber of ages wrapped hill and vale. Invisible giants have wrought and delved here of whom we never catch a glimpse, nor shall we, wait and watch we never so long. No sound of their hammers or picks or shovels or of the dynamite ever breaks the stillness of the air.

I have to believe that the valleys and mountains of my native Catskills were carved out of a great elevated plain or plateau; there is no other explanation of them. Here lie the level strata, without any bending or folding, or sign of convulsion and upheavals, horizontal as the surface of the sea or lake in which their sediments were originally laid down; and here are these deep, wide valleys cut down through these many sheets of stratified rock; and here are these long, high, broad-backed mountains, made up of the rock that the forces of air and water have left, and with no forces of erosion at work that would appreciably alter a line of the landscape in ten thousand years; and yet we know, if we know anything about the physical history of the earth, that erosion has done this work, carved out these mountains and valleys, from the Devonian strata, as literally as the sculptor carves his statue from the block of marble.

Above my lodge on the home farm the vast layers of the gray, thin-sheeted Catskill rock crop out and look across the valley to their fellows two or more miles away where they crop out in a similar manner on the opposite slope of the mountain. With the eye of faith I see the great sheets restored, and follow them across on the line which they made aeons ago, till they are joined again to their fellows as they were before the agents of erosion had so widely severed them.

These physical forces have worked as slowly and silently in sculpturing the landscapes as the biological laws have worked in evolving man from the lower animals, or the vertebrates from the invertebrates. The rains, the dews, the snows, the winds–how could these soft, gently careering agents have demolished these rocks and dug these valleys? One would almost as soon expect the wings and feet of the birds to wear away the forests they flit through. The wings of time are feathered also, and as they brush against the granite or the flinty sandstone no visible particle is removed while you watch and wait. Come back in a thousand years, and you note no change, save in the covering of trees and verdure. Return in ten thousand, and you would probably find the hills carrying their heads as high and as proudly as ever. Here and there the face of the cliff may have given way, or a talus slid into the valley, or a stream or river changed its course, or sawed deeper into the rock, and a lake been turned into a marsh, or the delta of a river broadened–minor changes, such as a shingle from your roof or a brick from your chimney, while your house stands as before. In one hundred thousand years what changes should we probably find? Here in the Catskills, where I write, the weathering of the hills and mountains would probably have been but slight. It must be fifty thousand years or more since the great ice-sheet left us. Where protected by a thin coat of soil, its scratches and grooves upon the surface rock are about as fresh and distinct as you may see them made in Alaska at the present time. Where the rock is exposed, they have weathered out, one eighth of an inch probably having been worn away. The drifting of the withered leaves of autumn, or of the snows of winter over them, it really seems, would have done as much in that stretch of time. Then try to fancy the eternity it has taken the subaerial elements to cut thousands of feet through this hard Catskill sandstone! No, the evolution of the landscape, the evolution of the animal and vegetable kingdoms, the evolution of the suns and planets, involve a process so slow, and on such a scale, that it is quite unthinkable. How long it took evolution to bridge the chasm between the vertebrate and the invertebrate, between the fish and the frog, between the frog and the reptile, between the reptile and the mammal, or between the lowest mammal and the highest, who can guess?

But the gulf has been passed, and here we are in this teeming world of life and beauty, with a terrible past behind us, but a brighter and brighter future before us.