The Romance of the Colorado River. Frederick Samuel DellenbaughЧитать онлайн книгу.
A side canyon is formed, draining a certain area. Another is formed elsewhere, and another, and so on till all drainage is through these tributaries and away from the brink, by more or less circuitous channels to the main stream. This backward drainage leaves the immediate brink, or "rim," till the last, in its work of erosion and corrasion, and the rim consequently is left higher than the region away from it. This effect of a backward drainage is very plain on both sides of the Grand Canyon, though it is somewhat assisted, on the north at least, by the backward dip of the strata. It may be modified by other conditions, so that it would not always be the case.
The basin of the Colorado, excepting that part below the mouth of the Virgen and a portion among the "parks" of the western slope of the Rocky Mountain range, is almost entirely a plateau region. Some of the plateaus are very dry; others rise above the arid zone and are well watered. The latter are called the "High Plateaus." They reach an altitude of eleven thousand feet above the sea. They are east of the Great Basin, and with the other plateaus form an area called by Powell "The Plateau Province." Eastward still the plateaus merge into the "parks." The High Plateaus, as a topographical feature, are a southern continuation of the Wasatch Mountains. They terminate on the south in the Markagunt, the Paunsagunt, and the Aquarius Plateaus. The extreme southern extremities of the two former are composed of mighty precipices of columnarly eroded limestone called the Pink Cliffs. Here is the beginning of the Terrace Plateaus, likewise bounded by vertical, barren cliffs. Between the High Plateaus and the parks, the plateaus may be called, for convenience, Mesa Plateaus, as they are generally outlined by vertical cliffs. This is the case also south of the end of the High Plateaus where, stepping down the great terraces, we arrive at the region immediately adjacent to the Grand Canyon, composed of four plateaus, three of them of mesa character, the Shewits, Uinkaret, Kanab, and Kaibab; and up at the head of Marble Canyon a fifth, the Paria, while still farther to the north-eastward is the Kaiparowitz. The edges of these Mesa Plateaus, precipitous cliffs, stretch for many miles across the arid land like mountain ranges split asunder. This region, lying between the High Plateaus, the Grand Wash, the Henry Mountains, and the Colorado, is perhaps the most fascinating of all the basin. The relief map at page 41 gives the larger part of it. In the basin there are also great mountain masses, the fountainheads of the waters which have carved the canyons. These are Uinta, Zuni, San Francisco, Henry, Pine Valley, Uinkaret, Beaver Dam, Virgen, Navajo, La Sal, and others, some reaching an altitude of more than twelve thousand feet. The highest peaks of these, and of course those of the Continental Divide on the east, which furnish a large proportion of the water of the Colorado, and the Wind River Mountains on the extreme north, have snow-banks throughout the summer. To show how dependent the Colorado is on the high peaks for its flood-waters, I will mention that it is not till the snows of these high altitudes are fiercely attacked by the sun in May and June that the river has its annual great rise. It would take only a slight lowering of the mean annual temperature now to furnish these peaks with ice caps. The rainfall in the lower arid regions is from three to ten inches, increasing northward to fifteen and twenty-five. On the peaks, of course, it is much greater. Almost any climate can be had, from the hot arid to the wet frigid. On the lower stretches, from Mohave down, the thermometer in summer stands around 112 degrees F. a great deal of the time, and reaches 118 degrees F. Yet Dr. Coues said he felt it no more than he did the summer heat of New York or Washington.* In winter the temperature at the bottom of the Grand Canyon is very mild, and flowers bloom most of the time. One November I descended from the snow-covered top of the Kaibab to the Grand Canyon at the mouth of the Kanab, where I was able to bathe in the open air with entire comfort.
* I was at the Needles one summer for a brief time, and the air
seemed very oppressive to me.
There are six chief topographical features, canyons, cliffs, valleys, mesa plateaus, high plateaus, mountains. There are two grand divisions: the lowland or desert, below the Virgen, and the plateau, but the topography of the immediate river course separates itself into four parts, the Green River Valley, the canyon, the valley-canyon, and the alluvial. The canyon part is the longest, occupying about two-thirds of the whole, or about 1200 miles. It is cut mainly through the plateaus. The last of these southward is the Colorado, a vast upheaval reaching from the lower end of the Grand Canyon south-east to about where the 34th parallel crosses the western line of New Mexico. Lieutenant Wheeler several times claims the honour of naming it (1868–71), but the name occurs on Lieutenant Ives's map of 1858. This plateau breaks sharply along its south-west line to the lowland district, and on its north-westerly edge slopes to the Little Colorado. It bears a noble pine forest, and from its summit rise to over 12,000 feet the volcanic peaks of the San Francisco Mountains. Its northern edge is the Grand Canyon, which separates it from its kindred on the other side. These and the Colorado Plateau rise to from 6000 to 8000 feet above sea-level, and it is through this huge mass that the river has ground out the Grand Canyon, by corrading its bed down tremendously, the bottom at the end being only 840 feet above the sea, whereas the start at the mouth of the Little Colorado is 2690. Yet here it is already 3500 feet below the surface at the end of Marble Canyon, which, separated only by the deep canyon of the Little Colorado, is practically a northward continuation of the Grand Canyon itself. As the river runs, the Grand Canyon is 217½ miles long. To this may be added the 65½ miles of Marble, giving a continuous chasm of 283 miles, the longest, deepest, and most difficult of passage in every direction of any canyon in the world. The depth begins with a couple of hundred feet at Lee's Ferry (mouth of the Paria), the head of Marble Canyon, and steadily deepens to some 3500 feet near the Little Colorado, where the sudden uplift of the Kaibab lends about 2000 feet more to the already magnificent gorge. Along the end of the Kaibab the walls, for a long distance, reach their greatest height, about 6000 feet, but the other side is considerably lower than the north all the way through. At the mouth of the Kanab the altitude of the river-bed is 1800 feet above the sea, showing a fall in the interval of 890 feet. The greatest declivity is about 210 feet in 10 miles, in what is termed the Kaibab division, extending from a point 10 miles below the Little Colorado to a point 58 miles farther down. Here the smooth stretches of river are long, the rapids short and violent. Here, also, is the "granite," making the walls sombre, as the colour is slaty to black. At the mouth of Diamond Creek the river is still 1300 feet higher than the sea, giving a fall of 500 feet from the Kanab. There is another descent of 460 feet to the Grand Wash, and then 149 to the mouth of the Virgen. Next to the Kaibab division of the Grand Canyon, the greatest declivity occurs in the Uinta region, in the Canyon of Lodore. The profile of the river in these two districts is approximately given on page 57. The average depth of the Grand Canyon is about 4000 feet. Its width at the top varies from 4½ to 12 miles. This is the extreme outer cliff-line. The inner gorge is much narrower, at the Toroweap being only about 3500 feet. The river varies in width from 500 or 600 feet to 75 or 100. In this canyon is water-power enough to run the machinery of the world, and there is as much more in the canyons above.
Joining Marble Canyon on the north is Glen, 149 miles long, from the Paria to Fremont River. It has but one rapid of consequence. At high water, with the exception of this rapid, the tide sweeps smoothly and swiftly down with a majestic flow. The walls are homogeneous sandstone, in places absolutely perpendicular for about a thousand feet. I have stood on the brink and dropped a stone into the river. The highest walls are 1600 feet. Next is Narrow Canyon, about 9 miles long, 1300 feet deep, and no rapids. It is hardly more than the finish of Cataract, a superb gorge about 40 miles long with a depth of 2700 feet, often nearly vertical. The rapids here are many and violent, the total fall being about 450 feet. At its head is the mouth of the Grand River. The altitude of the junction is 3860 feet.* Following up the Green, we have first Stillwater, then Labyrinth Canyon, much alike, the first 42¾ and the second 62½ miles in length. The walls of sandstone are 1300 feet. Their names well describe them, though the stillwater of the first is very swift and straight. There are no rapids in either. All these canyon names, from Green River Valley to the Grand Wash, were applied by Powell. Between Labyrinth and the next canyon, Gray, so called from the colour of its walls, 2000 feet high, is Gunnison Valley, where the river may first be easily crossed. Here the unfortunate Captain Gunnison, in 1853, passed over on his way to his doom, and here, too, the Old Spanish Trail led the traveller in former days toward Los Angeles. The Denver and Rio Grande Western Railway has taken advantage of the same place to cross. The 36 miles of Gray are hardly more than a continuation of the Canyon of Desolation's 97 miles. Desolation is a fine chasm, whose walls are 2400