Kitabı oku: «Steep Trails», sayfa 9

XIV. Nevada's Timber Belt¹⁹

The pine woods on the tops of the Nevada mountains are already shining and blooming in winter snow, making a most blessedly refreshing appearance to the weary traveler down on the gray plains. During the fiery days of summer the whole of this vast region seems so perfectly possessed by the sun that the very memories of pine trees and snow are in danger of being burned away, leaving one but little more than dust and metal. But since these first winter blessings have come, the wealth and beauty of the landscapes have come fairly into view, and one is rendered capable of looking and seeing.

The grand nut harvest is over, as far as the Indians are concerned, though perhaps less than one bushel in a thousand of the whole crop has been gathered. But the squirrels and birds are still busily engaged, and by the time that Nature's ends are accomplished, every nut will doubtless have been put to use.

All of the nine Nevada conifers mentioned in my last letter are also found in California, excepting only the Rocky Mountain spruce, which I have not observed westward of the Snake Range. So greatly, however, have they been made to vary by differences of soil and climate, that most of them appear as distinct species. Without seeming in any way dwarfed or repressed in habit, they nowhere develop to anything like California dimensions. A height of fifty feet and diameter of twelve or fourteen inches would probably be found to be above the average size of those cut for lumber. On the margin of the Carson and Humboldt Sink the larger sage bushes are called "heavy timber"; and to the settlers here any tree seems large enough for saw-logs.

Mills have been built in the most accessible canyons of the higher ranges, and sufficient lumber of an inferior kind is made to supply most of the local demand. The principal lumber trees of Nevada are the white pine (Pinus flexilis), foxtail pine, and Douglas spruce, or "red pine," as it is called here. Of these the first named is most generally distributed, being found on all the higher ranges throughout the State. In botanical characters it is nearly allied to the Weymouth, or white, pine of the Eastern States, and to the sugar and mountain pines of the Sierra. In open situations it branches near the ground and tosses out long down-curving limbs all around, often gaining in this way a very strikingly picturesque habit. It is seldom found lower than nine thousand feet above the level of the sea, but from this height it pushes upward over the roughest ledges to the extreme limit of tree growth—about eleven thousand feet.

On the Hot Creek, White Pine, and Golden Gate ranges we find a still hardier and more picturesque species, called the foxtail pine, from its long dense leaf-tassels. About a foot or eighteen inches of the ends of the branches are densely packed with stiff outstanding needles, which radiate all around like an electric fox- or squirrel-tail. The needles are about an inch and a half long, slightly curved, elastic, and glossily polished, so that the sunshine sifting through them makes them burn with a fine silvery luster, while their number and elastic temper tell delightfully in the singing winds.

This tree is pre-eminently picturesque, far surpassing not only its companion species of the mountains in this respect, but also the most noted of the lowland oaks and elms. Some stand firmly erect, feathered with radiant tail tassels down to the ground, forming slender, tapering towers of shining verdure; others with two or three specialized branches pushed out at right angles to the trunk and densely clad with the tasseled sprays, take the form of beautiful ornamental crosses. Again, in the same woods you find trees that are made up of several boles united near the ground, and spreading in easy curves at the sides in a plane parallel to the axis of the mountain, with the elegant tassels hung in charming order between them the whole making a perfect harp, ranged across the main wind-lines just where they may be most effective in the grand storm harmonies. And then there is an infinite variety of arching forms, standing free or in groups, leaning away from or toward each other in curious architectural structures,—innumerable tassels drooping under the arches and radiating above them, the outside glowing in the light, masses of deep shade beneath, giving rise to effects marvelously beautiful,—while on the roughest ledges of crumbling limestone are lowly old giants, five or six feet in diameter, that have braved the storms of more than a thousand years. But, whether old or young, sheltered or exposed to the wildest gales, this tree is ever found to be irrepressibly and extravagantly picturesque, offering a richer and more varied series of forms to the artist than any other species I have yet seen.

One of the most interesting mountain excursions I have made in the State was up through a thick spicy forest of these trees to the top of the highest summit of the Troy Range, about ninety miles to the south of Hamilton. The day was full of perfect Indian-summer sunshine, calm and bracing. Jays and Clarke crows made a pleasant stir in the foothill pines and junipers; grasshoppers danced in the hazy light, and rattled on the wing in pure glee, reviving suddenly from the torpor of a frosty October night to exuberant summer joy. The squirrels were working industriously among the falling nuts; ripe willows and aspens made gorgeous masses of color on the russet hillsides and along the edges of the small streams that threaded the higher ravines; and on the smooth sloping uplands, beneath the foxtail pines and firs, the ground was covered with brown grasses, enriched with sunflowers, columbines, and larkspurs and patches of linosyris, mostly frost-nipped and gone to seed, yet making fine bits of yellow and purple in the general brown.

At a height of about ninety-five hundred feet we passed through a magnificent grove of aspens, about a hundred acres in extent, through which the mellow sunshine sifted in ravishing splendor, showing every leaf to be as beautiful in color as the wing of a butterfly, and making them tell gloriously against the evergreens. These extensive groves of aspen are a marked feature of the Nevada woods. Some of the lower mountains are covered with them, giving rise to remarkably beautiful masses of pale, translucent green in spring and summer, yellow and orange in autumn, while in winter, after every leaf has fallen, the white bark of the boles and branches seen in mass seems like a cloud of mist that has settled close down on the mountain, conforming to all its hollows and ridges like a mantle, yet roughened on the surface with innumerable ascending spires.

Just above the aspens we entered a fine, close growth of foxtail pine, the tallest and most evenly planted I had yet seen. It extended along a waving ridge tending north and south and down both sides with but little interruption for a distance of about five miles. The trees were mostly straight in the bole, and their shade covered the ground in the densest places, leaving only small openings to the sun. A few of the tallest specimens measured over eighty feet, with a diameter of eighteen inches; but many of the younger trees, growing in tufts, were nearly fifty feet high, with a diameter of only five or six inches, while their slender shafts were hidden from top to bottom by a close, fringy growth of tasseled branchlets. A few white pines and balsam firs occur here and there, mostly around the edges of sunny openings, where they enrich the air with their rosiny fragrance, and bring out the peculiar beauties of the predominating foxtails by contrast.

Birds find grateful homes here—grouse, chickadees, and linnets, of which we saw large flocks that had a delightfully enlivening effect. But the woodpeckers are remarkably rare. Thus far I have noticed only one species, the golden-winged; and but few of the streams are large enough or long enough to attract the blessed ousel, so common in the Sierra.

On Wheeler's Peak, the dominating summit of the Snake Mountains, I found all the conifers I had seen on the other ranges of the State, excepting the foxtail pine, which I have not observed further east than the White Pine range, but in its stead the beautiful Rocky Mountain spruce. First, as in the other ranges, we find the juniper and nut pine; then, higher, the white pine and balsam fir; then the Douglas spruce and this new Rocky Mountain spruce, which is common eastward from here, though this range is, as far as I have observed, its western limit. It is one of the largest and most important of Nevada conifers, attaining a height of from sixty to eighty feet and a diameter of nearly two feet, while now and then an exceptional specimen may be found in shady dells a hundred feet high or more.

The foliage is bright yellowish and bluish green, according to exposure and age, growing all around the branchlets, though inclined to turn upward from the undersides, like that of the plushy firs of California, making remarkably handsome fernlike plumes. While yet only mere saplings five or six inches thick at the ground, they measure fifty or sixty feet in height and are beautifully clothed with broad, level, fronded plumes down to the base, preserving a strict arrowy outline, though a few of the larger branches shoot out in free exuberance, relieving the spire from any unpicturesque stiffness of aspect, while the conical summit is crowded with thousands of rich brown cones to complete its beauty.

We made the ascent of the peak just after the first storm had whitened its summit and brightened the atmosphere. The foot-slopes are like those of the Troy range, only more evenly clad with grasses. After tracing a long, rugged ridge of exceedingly hard quartzite, said to be veined here and there with gold, we came to the North Dome, a noble summit rising about a thousand feet above the timberline, its slopes heavily tree-clad all around, but most perfectly on the north. Here the Rocky Mountain spruce forms the bulk of the forest. The cones were ripe; most of them had shed their winged seeds, and the shell-like scales were conspicuously spread, making rich masses of brown from the tops of the fertile trees down halfway to the ground, cone touching cone in lavish clusters. A single branch that might be carried in the hand would be found to bear a hundred or more.

Some portions of the wood were almost impenetrable, but in general we found no difficulty in mazing comfortably on over fallen logs and under the spreading boughs, while here and there we came to an opening sufficiently spacious for standpoints, where the trees around their margins might be seen from top to bottom. The winter sunshine streamed through the clustered spires, glinting and breaking into a fine dust of spangles on the spiky leaves and beads of amber gum, and bringing out the reds and grays and yellows of the lichened boles which had been freshened by the late storm; while the tip of every spire looking up through the shadows was dipped in deepest blue.

The ground was strewn with burs and needles and fallen trees; and, down in the dells, on the north side of the dome, where strips of aspen are imbedded in the spruces, every breeze sent the ripe leaves flying, some lodging in the spruce boughs, making them bloom again, while the fresh snow beneath looked like a fine painting.

Around the dome and well up toward the summit of the main peak, the snow-shed was well marked with tracks of the mule deer and the pretty stitching and embroidery of field mice, squirrels, and grouse; and on the way back to camp I came across a strange track, somewhat like that of a small bear, but more spreading at the toes. It proved to be that of a wolverine. In my conversations with hunters, both Indians and white men assure me that there are no bears in Nevada, notwithstanding the abundance of pine-nuts, of which they are so fond, and the accessibility of these basin ranges from their favorite haunts in the Sierra Nevada and Wahsatch Mountains. The mule deer, antelope, wild sheep, wolverine, and two species of wolves are all of the larger animals that I have seen or heard of in the State.

XV. Glacial Phenomena in Nevada²⁰

The monuments of the Ice Age in the Great Basin have been greatly obscured and broken, many of the more ancient of them having perished altogether, leaving scarce a mark, however faint, of their existence—a condition of things due not alone to the long-continued action of post-glacial agents, but also in great part to the perishable character of the rocks of which they were made. The bottoms of the main valleys, once grooved and planished like the glacier pavements of the Sierra, lie buried beneath sediments and detritus derived from the adjacent mountains, and now form the arid sage plains; characteristic U-shaped canyons have become V-shaped by the deepening of their bottoms and straightening of their sides, and decaying glacier headlands have been undermined and thrown down in loose taluses, while most of the moraines and striae and scratches have been blurred or weathered away. Nevertheless, enough remains of the more recent and the more enduring phenomena to cast a good light well back upon the conditions of the ancient ice sheet that covered this interesting region, and upon the system of distinct glaciers that loaded the tops of the mountains and filled the canyons long after the ice sheet had been broken up.

The first glacial traces that I noticed in the basin are on the Wassuck, Augusta, and Toyabe ranges, consisting of ridges and canyons, whose trends, contours, and general sculpture are in great part specifically glacial, though deeply blurred by subsequent denudation. These discoveries were made during the summer of 1876-77. And again, on the 17th of last August, while making the ascent of Mount Jefferson, the dominating mountain of the Toquima range, I discovered an exceedingly interesting group of moraines, canyons with V-shaped cross sections, wide neve amphitheatres, moutoneed rocks, glacier meadows, and one glacier lake, all as fresh and telling as if the glaciers to which they belonged had scarcely vanished.

The best preserved and most regular of the moraines are two laterals about two hundred feet in height and two miles long, extending from the foot of a magnificent canyon valley on the north side of the mountain and trending first in a northerly direction, then curving around to the west, while a well-characterized terminal moraine, formed by the glacier towards the close of its existence, unites them near their lower extremities at a height of eighty-five hundred feet. Another pair of older lateral moraines, belonging to a glacier of which the one just mentioned was a tributary, extend in a general northwesterly direction nearly to the level of Big Smoky Valley, about fifty-five hundred feet above sea level.

Four other canyons, extending down the eastern slopes of this grand old mountain into Monito Valley, are hardly less rich in glacial records, while the effects of the mountain shadows in controlling and directing the movements of the residual glaciers to which all these phenomena belonged are everywhere delightfully apparent in the trends of the canyons and ridges, and in the massive sculpture of the neve wombs at their heads. This is a very marked and imposing mountain, attracting the eye from a great distance. It presents a smooth and gently curved outline against the sky, as observed from the plains, and is whitened with patches of enduring snow. The summit is made up of irregular volcanic tables, the most extensive of which is about two and a half miles long, and like the smaller ones is broken abruptly down on the edges by the action of the ice. Its height is approximately eleven thousand three hundred feet above the sea.

A few days after making these interesting discoveries, I found other well-preserved glacial traces on Arc Dome, the culminating summit of the Toyabe Range. On its northeastern slopes there are two small glacier lakes, and the basins of two others which have recently been filled with down-washed detritus. One small residual glacier lingered until quite recently beneath the coolest shadows of the dome, the moraines and neve-fountains of which are still as fresh and unwasted as many of those lying at the same elevation on the Sierra—ten thousand feet—while older and more wasted specimens may be traced on all the adjacent mountains. The sculpture, too, of all the ridges and summits of this section of the range is recognized at once as glacial, some of the larger characters being still easily readable from the plains at a distance of fifteen or twenty miles.

The Hot Creek Mountains, lying to the east of the Toquima and Monito ranges, reach the culminating point on a deeply serrate ridge at a height of ten thousand feet above the sea. This ridge is found to be made up of a series of imposing towers and pinnacles which have been eroded from the solid mass of the mountain by a group of small residual glaciers that lingered in their shadows long after the larger ice rivers had vanished. On its western declivities are found a group of well-characterized moraines, canyons, and roches moutonnees, all of which are unmistakably fresh and telling. The moraines in particular could hardly fail to attract the eye of any observer. Some of the short laterals of the glaciers that drew their fountain snows from the jagged recesses of the summit are from one to two hundred feet in height, and scarce at all wasted as yet, notwithstanding the countless storms that have fallen upon them, while cool rills flow between them, watering charming gardens of arctic plants—saxifrages, larkspurs, dwarf birch, ribes, and parnassia, etc.—beautiful memories of the Ice Age, representing a once greatly extended flora.

In the course of explorations made to the eastward of here, between the 38th and 40th parallels, I observed glacial phenomena equally fresh and demonstrative on all the higher mountains of the White Pine, Golden Gate, and Snake ranges, varying from those already described only as determined by differences of elevation, relations to the snow-bearing winds, and the physical characteristics of the rock formations.

On the Jeff Davis group of the Snake Range, the dominating summit of which is nearly thirteen thousand feet in elevation, and the highest ground in the basin, every marked feature is a glacier monument—peaks, valleys, ridges, meadows, and lakes. And because here the snow-fountains lay at a greater height, while the rock, an exceedingly hard quartzite, offered superior resistance to post-glacial agents, the ice-characters are on a larger scale, and are more sharply defined than any we have noticed elsewhere, and it is probably here that the last lingering glacier of the basin was located. The summits and connecting ridges are mere blades and points, ground sharp by the glaciers that descended on both sides to the main valleys. From one standpoint I counted nine of these glacial channels with their moraines sweeping grandly out to the plains to deep sheer-walled neve-fountains at their heads, making a most vivid picture of the last days of the Ice Period.

I have thus far directed attention only to the most recent and appreciable of the phenomena; but it must be borne in mind that less recent and less obvious traces of glacial action abound on ALL the ranges throughout the entire basin, where the fine striae and grooves have been obliterated, and most of the moraines have been washed away, or so modified as to be no longer recognizable, and even the lakes and meadows, so characteristic of glacial regions, have almost entirely vanished. For there are other monuments, far more enduring than these, remaining tens of thousands of years after the more perishable records are lost. Such are the canyons, ridges, and peaks themselves, the glacial peculiarities of whose trends and contours cannot be hid from the eye of the skilled observer until changes have been wrought upon them far more destructive than those to which these basin ranges have yet been subjected.

It appears, therefore, that the last of the basin glaciers have but recently vanished, and that the almost innumerable ranges trending north and south between the Sierra and the Wahsatch Mountains were loaded with glaciers that descended to the adjacent valleys during the last glacial period, and that it is to this mighty host of ice streams that all the more characteristic of the present features of these mountain ranges are due.

But grand as is this vision delineated in these old records, this is not all; for there is not wanting evidence of a still grander glaciation extending over all the valleys now forming the sage plains as well as the mountains. The basins of the main valleys alternating with the mountain ranges, and which contained lakes during at least the closing portion of the Ice Period, were eroded wholly, or in part, from a general elevated tableland, by immense glaciers that flowed north and south to the ocean. The mountains as well as the valleys present abundant evidence of this grand origin.

The flanks of all the interior ranges are seen to have been heavily abraded and ground away by the ice acting in a direction parallel with their axes. This action is most strikingly shown upon projecting portions where the pressure has been greatest. These are shorn off in smooth planes and bossy outswelling curves, like the outstanding portions of canyon walls. Moreover, the extremities of the ranges taper out like those of dividing ridges which have been ground away by dividing and confluent glaciers. Furthermore, the horizontal sections of separate mountains, standing isolated in the great valleys, are lens-shaped like those of mere rocks that rise in the channels of ordinary canyon glaciers, and which have been overflowed or pastflowed, while in many of the smaller valleys roches moutonnees occur in great abundance.

Again, the mineralogical and physical characters of the two ranges bounding the sides of many of the valleys indicate that the valleys were formed simply by the removal of the material between the ranges. And again, the rim of the general basin, where it is elevated, as for example on the southwestern portion, instead of being a ridge sculptured on the sides like a mountain range, is found to be composed of many short ranges, parallel to one another, and to the interior ranges, and so modeled as to resemble a row of convex lenses set on edge and half buried beneath a general surface, without manifesting any dependence upon synclinal or anticlinal axes—a series of forms and relations that could have resulted only from the outflow of vast basin glaciers on their courses to the ocean.

I cannot, however, present all the evidence here bearing upon these interesting questions, much less discuss it in all its relations. I will, therefore, close this letter with a few of the more important generalizations that have grown up out of the facts that I have observed. First, at the beginning of the glacial period the region now known as the Great Basin was an elevated tableland, not furrowed as at present with mountains and valleys, but comparatively bald and featureless.

Second, this tableland, bounded on the east and west by lofty mountain ranges, but comparatively open on the north and south, was loaded with ice, which was discharged to the ocean northward and southward, and in its flow brought most, if not all, the present interior ranges and valleys into relief by erosion.

Third, as the glacial winter drew near its close the ice vanished from the lower portions of the basin, which then became lakes, into which separate glaciers descended from the mountains. Then these mountain glaciers vanished in turn, after sculpturing the ranges into their present condition.

Fourth, the few immense lakes extending over the lowlands, in the midst of which many of the interior ranges stood as islands, became shallow as the ice vanished from the mountains, and separated into many distinct lakes, whose waters no longer reached the ocean. Most of these have disappeared by the filling of their basins with detritus from the mountains, and now form sage plains and "alkali flats."

The transition from one to the other of these various conditions was gradual and orderly: first, a nearly simple tableland; then a grand mer de glace shedding its crawling silver currents to the sea, and becoming gradually more wrinkled as unequal erosion roughened its bed, and brought the highest peaks and ridges above the surface; then a land of lakes, an almost continuous sheet of water stretching from the Sierra to the Wahsatch, adorned with innumerable island mountains; then a slow desiccation and decay to present conditions of sage and sand.