coloured—buff, gray, red, brown, and chocolate; never lichened, never moss-covered, but bare and often polished.”

The above description by Major J. W. Powell, who has explored the cañons of the Colorado, gives a graphic pen-picture of the lower and more arid plateaus of this region.

Nearly every watercourse, whether the stream be

perennial or not, is a cañon ; a narrow valley, with precipitous walls, often of enormous height. In many cases these cañons are so numerous that they cut the plateau into shreds—a mere skeleton of a country. Of such a section Lieutenant Ives, who explored the course of the lower Colorado, writes : “ The extent and magnitude of the system of cañons in that direction is astounding. The plateau is cut into shreds by these gigantic chasms, and resembles a vast ruin. Belts of country, miles in width, have been swept away, leaving only isolated mountains standing in the gap; fissures so profound that the eye cannot penetrate their depths are separated by walls whose thickness one can almost span; and slender spires, that seem tottering on their base, shoot up a thousand feet from vaults below.”

But few of these cañons contain water throughout the year. Most of them are dry at all times, excepting for a few days in the early spring, or for a few minutes or hours at most after a heavy shower. It is a characteristic of western North America, as of all arid countries, that the streams, away from their sources in the mountains, lose water, rather than gain it, in traversing the lower country. The dry atmosphere and the thirsty soil absorb it, and, in very many cases, large streams entirely disappear in this way.

This is the case to a great extent in the plateau country, and still more so in the Great Basin, where these are the only outlets to the drainage.

A few words will suffice to sketch the manner in which the climate has acted in producing these strange and unique orographic effects. The great degree of aridity of the atmosphere, and the slight rainfall, coupled with its sudden, explosive character, render plant - life very limited in amount. The soil, having little or no protection against the sudden floods, is washed away nearly as fast as it is formed; or, in other words, transportation nearly or quite keeps pace with disintegration. The rains, coming as they always do in floods, run immediately off the bare rock, or over and through the thin sandy soil, sweeping it with them; and, collecting in the little runs with incredible rapidity, rush down them in great body and with great velocity, sweeping everything before them. The waters are turbid and thick with

F

sediment, coarse and sharp-edged from the rapid cutting of the rocks. It is this detritus which Dame Nature uses as her chisel in carving cañons, cliffs, buttes, and the other quaint and curious forms which one meets in this strange land. A clear stream, whatever may be its velocity, has little erosive power; but put these tools in its possession, give it the quantity of coarse sand and gravel which the Colorado and its tributaries always hold in suspension, and its cutting power is enormous. The difference in climatic conditions between the district under discussion and the plains is one of degree only, but it is sufficient to produce very marked differences in orographic forms. Wherever the climatic conditions are such that soil can be formed and be covered with vegetation, there cañons cannot be produced, other than as gaps for the passage of streams through mountain ranges; but, in proportion as the climate becomes more arid, so will the country approach, in its physical features, a cañon land.

The Cañons of the Green and Colorado Rivers

While every stream in this region flows in a cañonand there are thousands of cañons which contain no streams whatever the most remarkable succession of cañons is that on the main stream of the region, the Colorado, and its principal branch, the Green. The cañons of this river were explored in 1869 by Major J. W. Powell. He started from Green River, in southwestern Wyoming, and safely threaded the devious and dangerous path of the river as far as the mouth of the Grand Wash, a distance of 1000 miles. Throughout this distance there are few miles where the river is not deep in the bowels of the earth.

The Green River, on leaving the Wind River Mountains, traverses southward a great plain or valley, known as the Green River Basin, at present an artemisia waste, but capable of being reclaimed, in large part, by irrigation. At the foot of this valley it meets the Uinta Range trending at right angles to its course. This range it traverses by a devious course, cutting gorges of enormous depth.

On emerging from these cañons, it enters another valley, quite similar to that above, but smaller, and known as the Uinta Basin. Traversing this, it gradually enters a cañon in sedimentary rocks. These beds, and the surface of the country with them, incline at a very low angle to the north, so that the stream in its southern progress is constantly getting deeper below the surface, until in a distance of 100 miles the cañon walls have risen to a height of 3300 feet above the river. At this point the walls break off abruptly, in a direction transverse to that of the river, leaving a small valley at the foot of the cliff.

Lower down there follow two similar cañons, but of less height and length. The inclined plateaus, in which these three cañons are cut, which slope to the north and break off abruptly on the south, extend east and west to the bases of the ranges which border this region, i.e. they extend across the plateau country. Of these plateaus Major Powell writes : “ Conceive of three geographic terraces, many hundred feet high, and many miles in width, forming a great stairway, from the Toompin Wunear Tuweap (the land of standing rocks) below, to the Uinta Valley above. The lower step of this stairway, the Orange Cliffs, is more than 1200 feet high, and the step itself is two or three score miles in width. The second step, the Book Cliffs, is 2000 feet high, or more, and a score of miles in width.

The third or upper step is more than 2000 feet high. Passing along this step for two or three score miles, we reach the valley of the Uinta ; but this valley is not 5000 or 6000 feet higher than the Toompin Wunear Tuweap, for the stairway is tipped backward.”

At the foot of the third cañon, another, Stillwater Cañon, immediately commences, and extends below the junction of the Grand and Green Rivers. The meeting of the waters takes place in the gloomy depths of this abyss, 1300 feet below the surface of the land.

A short distance above their junction, the surface of the country begins to rise with a long, gentle slope towards the summit of a fold. Stillwater and Cataract Cañons are cut in this fold. The walls grow gradually higher, but before the river reaches the axis of the fold it seems to become discouraged at the prospect of the difficulties ahead, and, turning nearly at right angles, it runs, diagonally to the axis, and as gradually, out of the fold, at the mouth of the Dirty Devil River. There is here a bit of open valley, and then another, Glen Cañon, succeeds. Its greatest depth is at its foot, at the mouth of the Paria, where it is 1600 feet.

Again the river runs into cañon, as if afraid of the sunlight. There is here another inclined plateau, sloping toward the north, and in it the river burrows deeper and deeper, until, at the mouth of the Colorado Chiquito, or Little Colorado, it is 3800 feet below the surface. This is Marble Cañon. The river has turned toward the west, and at the foot of this cañon or- for this is continuous with the Grand Cañon—at the foot of this portion, the general course of the river is west. At this point it is crossed by the Paria fold, in which the throw is to the west, thus suddenly increasing the depth of the canon by adding to the elevation of the country.