cutting down accompanied it with equal speed. The river, laden with rock débris, was the saw, to use Major Powell's apt illustration, and the formation of the uprising earth's crust was the log, and as fast as the uplifting forces supplied the log the saw cut through it. And these processes continued, until not only the eleven thousand feet of Eocene and Mesozoic strata were washed through, but the saw rasped into the Carboniferous, made sharper and keener by the destruction and removal of the beds of Eocene and Mesozoic which had once covered the Carboniferous.

And had the uplift not ceased, the sawing processes would have continued until many thousand more feet, perhaps, of the Archæan and Plutonic rocks had been exposed, and some of earth's most esoteric transactions revealed.

And this is the theory Newberry, Powell, and Dutton present to us as the only rational explanation of the existence of the various canyons of the Colorado River. It is accepted almost without question by all the great geologists of the world, and by them is believed to be the only theory that satisfactorily accounts for all the existing conditions.

But during all these æons of uplift and subsidence, erosion and corrasion, were there no greater forces at work? Are there no evidences of earthquakes, active volcanoes, and the like, to more satisfactorily account for this stupendous phenomenon? These are questions perpetually asked by those of less geological knowledge.

Complex questions, indeed, yet the geologists are

almost a unit in answering them. Earthquakes, volcanoes, faultings, flexurings? Yes, in great quantity, but as subsidiary, not primary, forces in the production of the Canyon.

Across the Grand Canyon and Plateau regions over fifteen faults of stupendous magnitude are found to exist. Some of these are hundreds of miles in extent, and the displacements vary from a few hundreds to upwards of seven thousand feet. Imagine the process. A great country, of thousands of square miles of area, split in half, one portion remaining on the level, and the other slowly but surely rising seven thousand feet above its original level, or subsiding to that extent.

It is the evidences of these great upheavals that puzzle the local and slightly informed geologists. They contend, and not without some show of reason, that these must have had some important influence in the creation and present appearance of the great Colorado waterway. Undoubtedly they have helped shape its ulterior form, but in a small and insignificant manner as compared with the great law of simultaneous uplift of the region and cutting down of the river's channel before outlined.

And it should not be forgotten here, by way of an important parenthesis, that, comparatively speaking, during all these years of cutting and rasping the river retained about the same level. It neither raised nor lowered. It went on flowing, and cut down its channel as fast as the uplifting forces fed the rock to its saw-like waters.

I have already described, in the chapter on the Mystic Spring Trail, the Wheeler Fold in Trail Can

yon. This is one of the earth's flexurings while the processes of uplift and subsidence and crust crumpling were going on. But I think it is evident that this took place in pre-carboniferous times, and therefore could not have had any influence in determining the course of a waterway that was made through strata deposited at a much later era, and which, as an impervious sheet, covered this and scores of similar folds and wrinkles throughout the region. The Uinkaret Mountains, which are clearly seen from the head of the Mystic Spring Trail, are purely volcanic, and their fiery floods of lava have poured in burning streams over the very edge of the Canyon's precipices, thus demonstrating an activity long after the Canyon was formed.

were once

It is not improbable that the San Francisco Mountains which are all volcanic an area of great depression in the plateau region whose denudation I have attempted to describe, and that, prior to that wholesale denudation, a chimney or rent in the earth's crust had afforded a vent for boiling lava from the molten mass beneath. This lava formed a crust over the area of depression, so that when, subsequently, the region round about was eroded, this lava crust acted as a protecting cap and saved the region from falling a prey to the otherwise irresistible forces. Thus, as the degradation continued, the erewhile depression became a prominence, and ultimately a mountain.

There are many other evidences of faultings, flexurings, and upheaval to be observed in the canyon region, and in the Bibliography published at the end of this volume the interested student will find a list of

those works that will aid him in his studies of these and all other geological phenomena connected with the Grand Canyon.

That the Grand Canyon region presents to the geologist a fascinating and unequalled field there can be no question, and he who seeks to penetrate the mysteries of nature's primitive forces will be wise if, ere he travels farther, he solves the problems here offered for solution.

I

CHAPTER XXXI

BOTANY OF THE GRAND CANYON

SHALL attempt no personal account of the botany of the Canyon, but merely introduce this heading to allow the insertion of two items from the Canyon Hotel Register at the Peach Springs Trail. Professor Asa Gray, of Harvard, America's greatest botanist, and Mrs. Gray, visited the Canyon May 3, 1885, and thus wrote in the register:

"Some conspicuous plants of the Canyon are: