Popular Science Monthly/Volume 68/April 1906/Making Geography While You Wait
|MAKING GEOGRAPHY WHILE YOU WAIT|
By THOMAS H. MACBRIDE,
UNIVERSITY OF IOWA
THOSE who read the daily newspaper, and the number of such is confessedly great, have no doubt been more than once of late mildly excited by certain sensational despatches from California, despatches intimating that certain large portions of that much-advertised commonwealth are actually rapidly disappearing from the sight and touch of men. It is reported that a large valley in the southernmost portion of the state is vanishing; has been assaulted by the sea; volcanoes are breaking up the solid ground beneath and the gray ocean is coming in to cover up the universal ruin.
Now something might be said in apology for the real-estate men of California who let go their holding in presence of assaults like these; and if it can be shown that any considerable bit of realty is actually disappearing and escaping, the violence of the natural agency responsible becomes a matter of probability, at least.
But it must be admitted that for the sensational stories referred to there is a certain basis of fact. In the Salton desert of southern California, where less than two years ago the traveler on the Southern Pacific railway saw only a wide vista of drifting sand, he now may skim along for miles beside a spreading sea, a sea that deepens from day to day and widens every moment. Within less than two years over many square miles, the whole face of the country has been changed. Railroads have been whelmed, stations and houses and factories lost in one encroaching flood; gulls and cranes run along a level beach where but a few months since the sage-hen nested, or the wild rabbits hid in sandy burrows. Surely, whether Neptune and Vulcan are busy or not, something has happened, and the passing traveler would like to know.
If we consult a map of the region in question and at the same time study the levels of the country, even as cited in the railway folder, though these are inexact, we shall speedily discover that the old Salton desert is indeed a basin, a basin of remarkable depth for its expanse, and wonderful in many ways. To make the case as simple as possible, the altitudes of points on the accompanying map are indicated. It appears, for instance, that the altitude of the station at Yuma, just east of the basin, is one hundred and thirty-seven feet. While the height of Salton station, about the middle of the valley, now whelmed, is actually two hundred and sixty-two feet below the level of the sea, say at the head of the Gulf of Lower California, about a hundred miles away! Indio, another railway station about one hundred and twenty-five miles west of Yuma and about twenty-five west of Salton, is almost at sea-level, so that it is evident that we have here a great depression not only below the Colorado which passes Yuma, but actually away below the
level of the sea. The extent of country actually below sea-level is included by the dotted lines upon our map. Now it is evident that if the volcanoes should once conclude to open up a way for oceanic waters, the sea might easily take possession of the Salton basin as the newspapers say; but have they done it?
It has been noted that the Colorado River at Yuma is far above the bottom of our basin, and it skirts along our southeast border to the gulf all the way, of course, far above the valley. In fact, with respect to the basin and its sloping sides, the river occupies exactly the position of a great irrigating main carried along some hillside above waiting fields. Some years ago enterprising men who saw the situation, realizing that large areas of the basin were not sand at all, but the finest sort of fertile alluvial soil, began to use this great natural main by constructing a secondary, carrying the waters of the Colorado out to the south part of our basin, near the Mexican boundary, where it was easy to bring under water some 100,000 acres of beautiful land. This artificial channel should bring part of the water of the river to certain old river channels emptying, or rather opening, into the lower part of the Salton basin. Recently, for the sake of wider service, new intakes from the Colorado have been opened. All went well until some eighteen months since, when the Colorado, flushed with flood, rose suddenly twenty feet or more above its usual tide and forthwith, instead of hurrying its waters southward to the gulf, began to pour them down the old abandoned river channels into the Salton sink. The fall to the gulf is only one hundred and thirty-seven feet, while the fall to the basin is, as we have seen, nearly four hundred and the distance not much greater! So there you are; and no earthquakes, volcanoes or sea-water needed in the least!
The whole situation and topography are interesting in the extreme. The geologist will tell you that all the region hereabouts is slowly rising; that once upon a time the head of the Gulf of California was farther north, away north of Yuma, in fact, and received the Colorado there, perhaps where the United States government is now building the new dam; and more, an arm of the gulf extended away west nearly to where now is Indio; and in those days the mud of the stream was deposited farther and farther out in the sea, forming an estuarine deposit, filling up the sea, while, upon the rising bottom, channels of the river ran carrying the mud farther and farther until finally the part of the sea toward Indio was cut off entirely from what now is called the Gulf. The part of the ocean thus isolated presently dried up and left the Salton basin, a salt desert by reason of the evaporated sea-water; and now again, though filled with the fresh water of the river, the wide-forming lake is salt once more in memory of its old-time history.
The botanist too finds curious confirmation of our story. All about the Salton valley, as near Indio and the Palm springs farther west are curious isolated groves of palms, palms of peculiar sort, the Washingtonia, in fact, now commonly planted in south California cities. But Washingtonia should stand by the sea, as the palms of Florida do, run down the shores of the California Gulf—and so these isolated groves are but the remnant of a tropic flora, once rich no doubt, that all but perished with the drying of the old Salton Sea of which geology tells. The old sea was a fact. Part of this beach is yet to be discovered, as is shown upon our map, and no doubt its course might be traced more widely still; its sands along the old-time eastern shore are still blowing about in dunes.
The waters of the Colorado, if allowed their present course, will no doubt bring back conditions of climate long gone by. Already railroad men declare the air too moist. If so, would the palms again extend their sway along the shores and would tropic verdure once more make the bordering mountains green? Who knows?