Timber-line in the high mountains of the West wakes up the most indifferent visitor. The uppermost limit of tree-growth shows nature in strange, picturesque forms, and is so graphic and impressive that all classes of visitors pause to look in silent wonder. This is the forest frontier.

It appears as old as the hills and as fixed and unchanging as they; but, like every frontier, that of the forest is aggressive, is ever struggling to advance. To-day this bold and definite line is the forest's Far North, its farthest reach up the heights; but this simply marks where the forest is, and not where it was or where it is striving to be. Here is the line of battle between the woods and the weather. The elements are insistent with "thus far and no farther," but the trees do not heed, and the relentless elements batter and defy them in a never-ending battle along the timber-line.

From a commanding promontory the forest-edge appears like a great shore-line, as it sweeps away for miles along the steep and uneven sides of the mountains. For the most part it follows the contour line; here it goes far out round a peninsula-like headland, there it sweeps away to fold back into cove or caÑon and form a forested bay. In Colorado and California this forest-line on the mountains is at an altitude of between eleven and twelve thousand feet. Downward from this line a heavy robe of dark forest drapes the mountains; above it the treeless heights rise cool and apparently barren, piled with old and eroded snowdrifts amid silent moorlands and rocky terraces.

The trees of timber-line are stunted by cold, crushed by snow, and distorted by prolonged and terrific winds. Many stretches appear like growths of coarse bushes and uncouth vines. They maintain a perpetual battle, and, though crippled, bent, dwarfed, and deformed, they are stocky and strong old warriors, determined, no weaklings, no cowards. They are crowded together and tangled, presenting a united front.

Few trees in this forest-front rise to a greater height than twelve feet. The average height is about eight feet, but the length of some of the prostrate ones is not far from the normal height. Wind and other hard conditions give a few trees the uncouth shapes of prehistoric animals. I measured a vine-like ichthyosaurus that was crawling to leeward, flat upon the earth. It was sixty-seven feet long, and close to the roots its body was thirty-eight inches in diameter. One cone-shaped spruce had a base diameter of four feet and came to a point a few inches less than four feet above the earth. Here and there a tough, tall tree manages to stand erect. The high wind either prevents growing or trims off all limbs that do not point to leeward. Some appear as though molded and pressed into shape. A profile of others, with long, streaming-bannered limbs, gives a hopeful view, for they present an unconquerable and conscious appearance, like tattered pennants or torn, triumphant battle-flags of the victorious forest!

The forest is incessantly aggressive and eternally vigilant to hold its territory and to advance. Winds are its most terrible and effective foe. To them is due its weird and picturesque front. Occasionally they rage for days without cessation, blowing constantly from the same quarter and at times with the rending and crushing velocity of more than one hundred miles an hour. These terrific winds frequently flay the trees with cutting blasts of sand. At times the wind rolls down the steeps with the crushing, flattening force of a tidal wave. Many places have the appearance of having been gone over by a terrible harrow or an enormous roller. In some localities all the trees, except the few protected by rocky ledges or closely braced by their encircling fellows, are crippled or overthrown.

Although I have visited timber-line in a number of States, most of my studies have been made on the eastern slope of the Continental Divide in Colorado. This ragged edge, with its ups and downs and curves, I have eagerly followed for hundreds of miles. Exploring this during every month of the year, I have had great days and nights along the timber-line. It was ever good to be with these trees in the clear air, up close to the wide and silent sky. Adventurers they appeared, strangely wrapped and enveloped in the shifting fog of low-drifting clouds. In the twilight they were always groups and forms of friendly figures, while by moonlight they were just a romantic camp of fraternal explorers.

Many a camp-fire I have had in the alpine outskirts of the forest. I remember especially one night, when I camped alone where pioneer trees, rusty cliffs, a wild lake-shore, and a subdued, far-off waterfall furnished sights and sounds as wild as though man had not yet appeared on earth. This night, for a time, a cave man directed my imagination, and it ran riot in primeval fields. After indulging these prehistoric visions, I made a great camp-fire with a monumental pile of tree-trunks and limbs on the shore of the lake, close to the cliff. These slow-grown woods were full of pitch, and the fire was of such blazing proportions that it would have caused consternation anywhere in Europe. The leaping, eager flames threw wavering lights across the lake on the steeply rising heights beyond. These brought the alarm cry of a coyote, with many an answer and echo, and the mocking laughter of a fox.

Even these wild voices in the primeval night were neither so strange nor so eloquent as the storm-made and resolute tree-forms that rose, peered, and vanished where my firelight fell and changed.

At most timber-lines the high winds always blow from one direction. On the eastern slope of the Colorado divide they are westerly, down the mountain. Many of the trees possess a long vertical fringe of limbs to leeward, being limbless and barkless to stormward. Each might serve as an impressive symbolic statue of a windstorm. Permanently their limbs stream to leeward together, with fixed bends and distortions as though changed to metal in the height of a storm.

Whenever a tree dies and remains standing, the sand-blasts speedily erode and carve its unevenly resistant wood into a totem pole which bears many strange embossed pictographs. In time these trees are entirely worn away by the violence of wind-blown ice-pellets and the gnawings of the sand-toothed gales.

Novel effects are here and there seen in long hedges of wind-trimmed trees. These are aligned by the wind. They precisely parallel the wind-current and have grown to leeward from the shelter of a boulder or other wind-break. Apparently an adventurous tree makes a successful stand behind the boulder; then its seeds or those of other trees proceed to form a crowding line to the leeward in the shelter thus afforded. Some of these hedges are a few hundred feet in length; rarely are they more than a few feet high or wide. At the front the sand-blasts trim this hedge to the height and width of the wind-break. Though there may be in some a slight, gradual increase in height from the front toward the rear, the wind trims off adventurous twigs on the side-lines and keeps the width almost uniform throughout.

During the wildest of winds I sometimes deliberately spent a day or a night in the most exposed places at timber-line, protected in an elkskin sleeping-bag. Wildly, grandly, the surging gusts boomed, ripped, roared, and exploded, as they struck or swept on. The experience was somewhat like lying in a diver's dress on a beach during a storm. At times I was struck almost breathless by an airy breaker, or tumbled and kicked indifferently about by the unbelievable violence of the wind. At other times I was dashed with sand and vigorously pelted with sticks and gravel.

This was always at some distance from tree, boulder, or ledge, for I took no risks of being tossed against trees or rocks. Many times, however, I have lain securely anchored and shielded beneath matted tree-growths, where in safety I heard the tempestuous booms and the wildest of rocket-like swishes of the impassioned and invisible ocean of air. The general sound-effect was a prolonged roar, with an interplay of rippings and tumultuous cheerings. There were explosions and silences. There were hours of Niagara. In the midst of these distant roarings the fearful approach of an advancing gale could be heard before the unseen breaker rolled down on me from the heights.

The most marked result of cold and snow is the extreme shortness of the growing-season which they allow the trees. Many inclined trees are broken off by snow, while others are prostrated. Though the trees are flattened upon the earth with a heavy load for months, the snow cover affords the trees much protection, from both the wracking violence of the winds and their devitalizing dryness. I know of a few instances of the winter snows piling so deeply that the covered trees were not uncovered by the warmth of the following summer. The trees suspended in this enforced hibernating sleep lost a summer's fun and failed to envelop themselves in the telltale ring of annual growth.

Snow and wind combined produce acres of closely matted growth that nowhere rises more than three feet above the earth. This growth is kept well groomed by the gale-flung sand, which clips persistent twigs and keeps it closely trimmed into an enormous bristle brush. In places the surface of this will support a pedestrian, but commonly it is too weak for this; and, as John Muir says, in getting through, over, under, or across growths of this kind, one loses all of his temper and most of his clothing!

Timber-line is largely determined by climatic limitations, by temperature and moisture. In the Rocky Mountains the dry winds are more deadly, and therefore more determining, than the high winds. During droughty winters these dry winds absorb the vital juices of hundreds of timber-line trees, whose withered standing skeletons frequently testify to the widespread depredations of this dry blight. A permanent advance, too, is made from time to time. Here and there is a grove, a permanent settlement ahead of and above the main ranks. In advance of these are a few lone trees, heroes scouting in the lead. In moist, sheltered places are seedlings and promising young trees growing up in front of the battle-scarred old guard. Advances on dry, wind-swept ridges are more difficult and much less frequent; on a few dry ridges these trees have met with a repulse and in some places have lost a little territory, but along most of its front the timber-line is slowly advancing into the heights.

With this environment it would be natural for these trees to evolve more hardiness than the present trees have. This would mean trees better fitted to contend with, and more likely to triumph over, the harsh conditions. Evolutionary development is the triumphing factor at the timber-line.

The highest timber-line in the world is probably on Mount Orizaba, Mexico. Frank M. Chapman says that there are short-leaved pines (Pinus MontezumÆ) from thirty to forty feet high, on the southern exposure of this peak at an altitude of about 13,800 feet. In Switzerland, along the steep and snowy Alps, it is sixty-four hundred; on Mt. Washington, about forty-five hundred feet. In the mountains of Colorado and California it is of approximately equal altitude, between eleven and twelve thousand feet. Advancing northward from California along the timber-line, one enters regions of heavy snow-fall as well as of restricting latitude. Combined, these speedily lower the altitude of timber-line, until on Mt. Rainier it is below eight thousand feet. There is a noticeable dwarfing of the forest as one approaches the Land of the Midnight Sun, and in its more northerly reaches it comes down to sea-level to form the Land of Little Sticks. It frays out at its Farthest North just within the Arctic Circle. Most of the Arctic Ocean's icy waves break on treeless shores.

Everywhere at timber-line the temperature is low, and on Long's Peak the daily average is two degrees below the freezing-point. At timber-line snow may fall any day of the year, and wintry conditions annually prevail from nine to ten months. The hardy trees which maintain this line have adjusted themselves to the extremely short growing-season, and now and then mature and scatter fertile seeds. The trees that do heroic service on all latitudinal and altitudinal timber-lines of the earth are members of the pine, spruce, fir, birch, willow, and aspen families. At timber-line on the Rocky Mountains there are three members each from the deciduous trees and the evergreens. These are the Engelmann spruce, limber pine, alpine fir, arctic willow, black birch, and quaking aspen.

A few timber-line trees live a thousand years, but half this time is a ripe old age for most timber-line veterans. The age of these trees cannot be judged by their size, nor by general appearance. There may be centuries of difference in the ages of two arm-in-arm trees of similar size. I examined two trees that were growing within a few yards of each other in the shelter of a crag. One was fourteen feet high and sixteen inches in diameter, and had three hundred and thirty-seven annual rings. The other was seven feet high and five inches in diameter, and had lived four hundred and ninety-two years!

One autumn a grizzly I was following—to learn his bill-of-fare—tore up a number of dwarfed trees at timber-line while digging out a woodchuck and some chipmunks. A number of the smaller trees I carried home for careful examination. One of these was a black birch with a trunk nine-tenths of an inch in diameter, a height of fifteen inches, and a limb-spread of twenty-two. It had thirty-four annual rings. Another was truly a veteran pine, though his trunk was but six-tenths of an inch in diameter, his height twenty-three inches, and his limb-spread thirty-one. His age was sixty-seven years. A midget that I carried home in my vest pocket was two inches high, had a limb-spread of about four inches, and was twenty-eight years of age.

A limber pine I examined was full of annual rings and experiences. A number of its rings were less than one hundredth of an inch in thickness. At the height of four feet its trunk took on an acute angle and extended nine feet to leeward, then rose vertically for three feet. Its top and limbs merged into a tangled mass about one foot thick, which spread out eight feet horizontally. It was four hundred and nine years old. It grew rapidly during its first thirty-eight years; then followed eighteen years during which it almost ceased growing; after this it grew evenly though slowly.

One day by the sunny and sheltered side of a boulder I found a tiny seed-bearer at an altitude of eleven thousand eight hundred feet. How splendidly unconscious it was of its size and its utterly wild surroundings! This brave pine bore a dainty cone, yet a drinking-glass would have completely housed both the tree and its fruit.

Many kinds of life are found at timber-line. One April I put on snowshoes and went up to watch the trees emerge from their months-old covering of snow. While standing upon a matted, snow-covered thicket, I saw a swelling of the snow produced by something moving beneath. "Plainly this is not a tree pulling itself free!" I thought, and stood still in astonishment. A moment later a bear burst up through the snow within a few yards of me and paused, blinking in the glare of light. No plan for immediate action occurred to me; so I froze. Presently the bear scented me and turned back for a look. After winking a few times as though half blinded, he galloped off easily across the compacted snow. The black bear and the grizzly occasionally hibernate beneath these low, matted tree-growths.

The mountain lion may prowl here during any month. Deer frequent the region in summer. Mountain sheep often take refuge beneath the clustered growths during the autumn storms. Of course the audacious pine squirrel comes to claim the very forest-edge and from a point of safety to scold all trespassers; and here, too, lives the cheery chipmunk.

This is the nursery, or summer residence, of many kinds of birds. The "camp-bird," the Rocky Mountain jay, is a resident. Here in spring the white-crowned sparrow sings and sings. During early summer the solitaire, the most eloquent songster I have ever heard, comes up from his nest just down the slope to pay a tribute of divine melody to the listening, time-worn trees. In autumn the Clarke crow appears and, with wild and half-weird calls of merriment, devours the fat nuts in the cones of the limber pine. During this nutting, magpies are present with less business than at any other time and apparently without a plan for deviltry. Possibly they are attracted and entertained by the boisterousness of the crows.

Lovely wild-flower gardens occupy many of the openings in this torn and bristling edge of the forest. In places acres are crowded so closely with thrifty, brilliant bloom that one hesitates to walk through and trample the flowers. Here the columbine, the paintbrush, the monument-plant, and scores of other bright blossoms cheer the wild frontier.

Rarely are strangers in the mountains thoroughly aroused. They need time or explanation in order to comprehend or appreciate the larger scenes, though they do, of course, have periodic outbursts in adjectives. But at timber-line the monumental scene at once has the attention, and no explanation is needed. Timber-line tells its own stirring story of frontier experience by a forest of powerful and eloquent tree statues and bold, battered, and far-extending figures in relief.

Only a few of the many young people whom I have guided to timber-line have failed to feel the significance of the scene, but upon one party fresh from college the eloquent pioneer spirit of the place made no impression, and they talked glibly and cynically of these faithful trees with such expressions as "A DorÉ garden!" "Ill-shapen fiends!" "How foolish to live here!" and "Criminal classes!" More appreciative was the little eight-year-old girl whose ascent of Long's Peak I have told of in "Wild Life on the Rockies." She paid the trees at timber-line as simple and as worthy a tribute as I have ever heard them receive: "What brave little trees to stay up here where they have to stand all the time with their feet in the snow!"

The powerful impressions received at timber-line lead many visitors to return for a better acquaintance, and from each visit the visitor goes away more deeply impressed: for timber-line is not only novel and strange, it is touched with pathos and poetry and has a life-story that is heroic. Its scenes are among the most primeval, interesting, and thought-compelling to be found upon the globe.

The Chinook Wind