The Western United States | Page 6

time. The little springs issue from the sandstone, and their limited supply of water is soon drunk up by the thirsty sands.
As far as the water flows it forms a little oasis upon the barren slope. Along the course of the streams are little patches of green grass, flowers, and bushes. Birds flit about, and there are tracks of small animals in the mud. Evidently the water is as great an attraction to them as it is to us. If a well were dug in the plateau above, we can understand now how deep it would have to be in order to reach water. A well three-fourths of a mile deep would be a difficult one to pump.
We are now in the bottom of the main ca?on, but deeper still is the last and inner gorge, through which the Colorado is flowing. For thousands of centuries the river has been sawing its way down into the earth. The precipitous cliffs which we have passed are formed of hard sandstone or limestone. The more gentle slopes consist of softer shales. Now the river has cut through them all and has reached the very heart of the earth, the solid granite.
[Illustration: FIG. 6.--THE INNER GORGE OF THE GRAND CA?ON OF THE COLORADO]
This inner gorge has almost vertical walls twelve hundred to fifteen hundred feet high. We can sit upon the brink under a ledge of rock which protects us from the hot sun, and watch the river as we eat our luncheon. Far below, almost directly under us, it rushes along. The roar of the current rises but faintly to our ears. The water is very muddy and not at all like the clear mountain streams, far away upon the continental divide, which unite to form the river. It seems as if the water, ashamed of its soiled appearance, wanted to hide from the sight of men. If so, it has succeeded well, for it can be seen only at rare intervals from the top of the ca?on walls, and even at the bottom of the main ca?on the river itself is not visible unless one stands upon the very brink of the granite gorge.
The work of the river is not yet done. It will go on until the great cliffs have crumbled and have been replaced by gentle slopes. It will not stop until, at some far distant time, a broad valley has been worn out of the rocky strata.
The ca?on appears much wider when viewed from the bottom than from the top, and the great cliffs far back along the trail seem less precipitous, but only because they are so far away. A weary climb of several miles awaits us. We must rest and take breath frequently or we shall not reach the top.
As night approaches and the shadows begin to fall, every turret and pinnacle stands out in bold relief. The bands of yellow and red shade into purple, and everything, save the long winding trail, begins to have a weird and mystical look.

HOW THE COLUMBIA PLATEAU WAS MADE
Years ago people disputed as to the way in which the earth was made. Those who lived where all the rocks had, like lava, the appearance of having once been melted, believed that fire had done all the work. Those who lived where the rocks appeared to be formed of hardened mud, sand, and lime, substances such as we find accumulating under water, said that water alone had been the means. But in later years the earth's surface has been more widely explored, and now it is known that both opinions were partly right. Water and fire have both been concerned in the making of the earth.
In the great valleys fire-formed rocks are rare, but they are more or less abundant in all mountainous regions, for where mountains are, there the crust of the earth is weakest. There are many reasons for believing that the interior of the earth is very hot. We know that the surface is settling in some places and rising in others, and that where the strain of the upheaval is too great the rocks are broken. These convulsions sometimes cause earthquakes and sometimes volcanic eruptions, when enormous quantities of molten rock are poured out over the surface. In all the long history of our earth probably no greater flood of lava than that which made the Columbia plateau was ever spread over the surface of any region. Travel where you will over the plains of southern Idaho, central Washington, or Oregon, and examine the rocks which here and there rise above the soil or are exposed in the ca?ons, and you will find that they all appear to have been formed by fire.
[Illustration: FIG. 7.--SNAKE RIVER AT IDAHO FALLS
Just beginning to cut a ca?on in the