The inland lake.
No one knows how many days, how many years, elapsed before the decrease of the water became noticeable. Doubtless the lake shrunk away slowly from the white face of the sand-dunes and the red walls of the mountains. The river-mouths that opened into the lake narrowed themselves to small stream-beds. The shelving beaches where the waves had fallen lazily year after year, pushing themselves over the sand in beautiful water-mirrors, shone bare and dry in the sunlight. The ragged reefs, over which the chop sea had tumbled and tossed so long, lifted their black hulks out of the water and with their hosts of barnacles and sea-life became a part of the land.
The first fall.
Springs and wells in the sea-bed.
The New River.
The waters of the great inland lake fell perhaps a hundred feet and then they made a pause. The exposed shores dried out. They baked hard in the sun, and were slowly ground down to sand and powdered silt by the action of the winds. The waters made a long pause. They were receiving reinforcements from some source. Possibly there was more rainfall in those days than now, and the streams entering the lake from the mountains were much larger. Again there may have been underground springs. There are flowing wells to-day in this old sea-bed—wells that cast up water salter than the sea itself. No one knows their fountain-head. Perhaps by underground channels the water creeps through from the Gulf, or comes from mountain reservoirs and turns saline by passing through beds of salt. These are the might-bes; but it is far more probable that the Colorado River at high water had made a breach of some kind in the dam of its own construction and had poured overflow water into the lake by way of a dry channel called the New River. The bed of this river runs northward from below the boundary-line of Lower California; and in 1893, during a rise in the Colorado, the waters rushed in and flooded the whole of what is called the Salton Basin. When the Colorado receded, the basin soon dried out again.
New beaches.
It was undoubtedly some accident of this kind that called the halt in the original recession. During the interim the lake had time to form new shores where the waves pounded and washed on the gravel as before until miles upon miles of new beach—pebbled, shelled, and sloping downward with great uniformity—came into existence. This secondary beach is intact to-day and looks precisely like the primary except that it is not quite so large. Across the basin, along the southern mountains, the second water-tracery is almost as apparent as the first. The rocks are eaten in long lines by wave-action, and are honeycombed by the ceaseless energies of the zoöphite.
The second fall.
Nor was the change in beach and rock alone. New bays and harbors were cut out from where the sea had been, new river-channels were opened down to the shrunken lake, new lagoons were spread over the flat places. Nature evidently made a great effort to repair the damage and adapt the lake to its new conditions. And the Indians, too, accepted the change. There are many indications in broken pottery, arrow-heads, and mortars that the aboriginal tribes moved down to the new beach and built wickiups by the diminished waters. And the old fishing-foraging-fighting life was probably resumed.