The Evolution of Worlds

by Percival Lowell

Map showing the glaciated area of North America—
the arrows indicating the direction of ice movement—
Chamberlin and Salisbury.

For it now appears that there was no glacial epoch. Our early ideas inculcated by text-books at school received a rude shock when it appeared that the glacial epoch was not, as we had been led to believe, a polar phenomenon at all, but a local affair which on the face of it had nothing to do with the pole. For investigation has disclosed that instead of emanating from the pole southward, it proceeded from certain centres, descending thence in all directions, north as much as south. Thus there was a centre in Norway in 65° N. lat. and another in Scotland in 56° N. In North America there were three—the Labradorian in latitude 54° N., the Kerwatin to the northwest of Hudson’s Bay in latitude 62° N., and the Cordilleran along the Pacific coast in latitude 58° N. On the other hand, northern Siberia, the coldest region in the world, was not glaciated. That the ice flowed off these centres proves them to have been higher than the sides. But we have further evidence of their then great height from the fact that dead littoral shells have been dredged from 1333 fathoms in the North Atlantic, and the prolongation under water of the fiords of Norway and of land valleys in North America witness to the same subsidence since.

But evidence refuses to stop here. The Alps were then more glaciated than they are now. So was Kilimanjaro and Ruwenzori on the equator; and finally at the same time more ice and snow existed round about the south pole than is the case to-day. Now this is really going too far even for the most ardent believers in the force of eccentricity. For if the astronomic causes postulated were true, they must have produced just the opposite action at the antipodes, to say nothing of the crux of being equally effective at the equator. The theory lies down like the ass between two burdens. Whichever load it chooses to saddle, it must perforce abandon the other.

So it turns out that the Ice Age was not an Ice Age at all but an untoward elevation of certain spots, and is to be relegated to the same limbo of exaggeration of a local incident into a world-wide cataclysm as the deluge. That some geologists will still cling to their former belief I doubt not; for as the philosophic old lady remarked: “There always have been two factions on every subject. Just as there are the suffragists and anti-suffragists now, so there were slaveholders and the anti-slavery people in my time; and even in the days of the deluge, there were the diluvians who were in favor of a flood and the antediluvians who were opposed to it.” A tale which has a peculiarly scientific moral, as in science anti and ante seem often interchangeable terms.

When I began the course of lectures that resulted in this volume, I labored under the apprehension that an account of cosmic physics might prove dull. It soon threatened to prove too startling. I therefore hasten to reassure the timid by saying that we are outgrowing ice ages and probably deluges. Elevations of the Earth’s crust are likely to be less and less pronounced in the future, and meanwhile such as exist are being slowly worn down. Secondly, the Sun is sure to continue of much the same efficiency for many æons to come. And lastly, the essential ingredient of both prodigies, water, is daily becoming more scarce. To this latter point we now turn, and perhaps when it is explained to him the reader may think that he has been rescued from one fate only to fall into the hands of another.

Geology is necessarily limited in its scope to what has happened; planetology is not so circumscribed in its domain. It may indulge in prognostication of the future, and find countenance for its conclusions in the physiognomy of other worlds. Thus one of the things which it foresees is the relative drying up of our abode. To those whose studies have never led them off this earth, the fact that the oceans are slowly evaporating into space may seem as incredible as would, to one marooned on a desert island, the march of mankind in the meantime. We live on an island in space, but can see something of the islands about us, and our conception of what is coming to our limited habitat can be judged most surely by what we note has happened to others more advanced than ourselves. Just as we look at Jupiter to perceive some likeness of what we once were, the real image of which has travelled by this time far into the depths of space beyond possibility of recall, so must we look to the Moon or Mars if we desire to see some faint adumbration of the pass to which we are likely to come. For from their lack of size they should have preceded us on the road we are bound to travel. Now, both these worlds to-day are water-lacking, in whole or part; the Moon practically absolutely so, Mars so far as any oceans or seas are concerned. We should do wisely then to take note. But we have more definite information than simply their present presentments. For both bear upon their faces marks of having held seas once upon a time. They were once, then, more as we are now. We cannot of course be sure, as we are unable to get near enough to scan their surfaces for signs of erosive action. But so far as we can make out, past seas best explain their appearance.