When originally laid down all these layers must have been nearly horizontal, just as they are deposited today in bodies of standing water all over the world. Then came a time when the sea slowly but permanently withdrew from the area by an uplift of the land, which since that time has been continuously above sea level. This uplift, one of the greatest in the history of the region, marks the beginning of a long period of erosion which has carved the mountains of Glacier National Park.
The geologist observes that the rock layers are no longer in the horizontal position in which they were laid down. There are folds in the rocks and many breaks or faults cutting across the layers.
Furthermore, the oldest rocks in the region are found to be resting on the younger rocks of the adjacent plains. One of the best examples of this is to be seen at Chief Mountain where the ancient limestone rests directly on the young shale below (fig. 1). The same relationship is visible in Cutbank, St. Mary, and Swiftcurrent Valleys. In these areas, however, the exact contact is not always so easy to locate princ.i.p.ally because of the debris of weathered rocks that have buried them. What has happened? How did this peculiar relationship come about? The answers to these questions unravel one of the grandest stories in earth history. Forces deep in the earth slowly gathered energy until finally the stress became so great that the rocky crust began to move.
The probable results of the movement in the crust of the earth are shown in the diagram (fig. 2). Section A represents a cross section of the Glacier Park region, as it most likely appeared, immediately following the long period of sedimentation. The rock strata are horizontal. Section B shows the same region after the rock layers have been slightly wrinkled due to the forces from the southwest, which, although slightly relieved by the bending, still persisted and the folds were greatly enlarged as shown in section C. At this stage the folds reached their breaking limit, and the strata broke in a number of places as indicated by dotted lines in the diagram. As a result of this fracturing, the rocks on the west side of the folds were pushed upward and over the rocks on the east, as shown in section D. The mountain rocks (represented by patterns of cross lines) were shoved over the rocks of the plains (represented in white), producing what is known as an "overthrust fault." It has been estimated that the rocks have moved a distance of at least 15 miles.
As the rocks were thrust northeastward and upward they made a greatly elevated region, but did not, however, at any time project into the air, as indicated in section D, because as the rocky ma.s.s was being uplifted, streams were wearing it away and cutting deep canyons in its upland portion. The rocks of the mountains, owing to their resistant character, are not worn away as rapidly as the plains formations with the result that great thicknesses of limestone and argillite tower above the plains. Where the older, more ma.s.sive strata overlie the soft rocks the mountains are terminated by precipitous walls as shown in section E. This explains the absence of foothills that is so conspicuous a feature of this mountain front and one in which it differs from most other ranges.
While the region now known as "Glacier National Park" was being uplifted and faulted, the streams were continually at work. The sand and other abrasive material being swept along on the beds of the streams slowly wore away much of the rock. The uplifting gave the streams life and they consequently cut deep valleys into the mountain area. They cut farther and farther back into the mountain ma.s.s until they dissected it, leaving instead of an upland plateau a region of ridges and sharp peaks. This erosional process which has carved the mountains of Glacier Park has produced most of the mountains of the world.
Following their early erosional history, there came a period of much colder climate during which time heavy snows fell and large ice fields were formed throughout the mountain region. At the same time huge continental ice sheets formed in Canada and also in northern Europe.
This period, during which glaciers, sometimes over a mile thick, covered many parts of the world including all of Canada and New England and much of North Central United States, is known as the "Ice Age."
Such a tremendous covering of ice had an enduring and p.r.o.nounced effect upon the relief of the country.
[Ill.u.s.tration: Figure 1.--_Sketch showing structure of Chief Mountain.
The ancient limestone above is not appreciably altered, but the lower part is broken up by many oblique thrust faults. The entire mountain is composed of ancient rocks and rests on shale of a very much younger age. After Bailey Willis._]
[Ill.u.s.tration: Figure 2.--_The Lewis overthrust. Diagram ill.u.s.trating how pressure from the northwest affected the rocks of the Glacier Park region._]
[Ill.u.s.tration: Figure 3.--_A, An irregular V-shaped valley produced by stream erosion; B, the same valley after it has been occupied by a glacier. Note the smooth topography and U-shaped form._]
In Glacier National Park some of the ice still remains in the higher portions of the valleys and a study of these ice fields helps in interpreting the history of the park during the Ice Age. It is evident that ice did not cover the entire range, but that the higher peaks stood out above the ice, which probably never reached a thickness of over 3,000 feet in this region. The V-shaped valleys which had been produced by stream erosion were filled with glaciers which moved slowly down the valleys. The ice froze onto all loose rock material and carried it forward, using it as abrasive to gouge out the rock, the valley bottoms, and sides. Gradually the valleys were molded until they had acquired a smooth U-shaped character (fig. 3). There are excellent examples of this work of ice in the park, among which are Two Medicine, Cut Bank, St. Mary, Swiftcurrent, and Belly River Valleys.
In addition to smoothing the valley down which they moved, the glaciers produced many rock basins called cirques. These are the result of ice plucking in the regions where the glaciers formed. Alternate freezing and thawing cause the rock to break and the resulting fragments are carried away by the moving ice ma.s.s. In the majority of cases the cirques have lakes on their floors. The park is dotted with these beautiful little lakes scattered throughout the high mountain country.
The valley lakes are usually larger than the cirque lakes and have a different origin. As the glaciers melted they deposited huge loads of sand, mud, and boulders in the valley bottoms called moraines. Debris of this nature has helped to hold in the waters of St. Mary, Lower Two Medicine, McDonald, Bowman, and numerous other lakes in the park.
FLORA AND FAUNA
Glacier National Park is exceptionally rich in many kinds of wildlife.
Its rugged wilderness character, enhanced by numerous lakes and almost unlimited natural alpine gardens, combine to offer an unexcelled opportunity to enjoy and study nature.
Glacier is noted for its brilliant floral display which is most striking in early July. Above timber line hardy plants such as mosses and lichens, together with the delicately colored alpine flowers, are found. Lower on the mountains are heather, gentians, wild heliotrope, and stunted trees of alpine fir, white-barked pine, and alpine larch.
The valleys on the east bear Engelmann spruce, alpine fir, lodgepole pine, Douglas fir, and limber pine.
The valleys of the west side are within an entirely different plant life zone, typified by dense climax forests. For the most part these forests consist of red cedar and hemlock, with intermediate forests of larch, fir, spruce, and white pine. There are also younger stands of larch and lodgepole pine. Some of the white pines in McDonald Valley have reached huge dimensions. The deficiency of wild flowers found there is in part made up by the presence of sphagnum bogs with a typical fauna and flora of their own.
On the east, at lower elevations, representatives of the Great Plains flora are found, such as the pa.s.sion flower, carpet pink, shooting star, scarlet paintbrush, red and white geraniums, bronze agoseris, the gaillardia, wild hollyhock, asters, and many other composites. The bear gra.s.s is one of the most characteristic plants of Glacier.
Of equal interest is the abundant animal life, including both the larger and smaller forms. Bighorn, mountain goats, moose, wapiti, grizzly and black bear, and western white-tailed and Rocky Mountain mule deer exist in as natural a condition as is possible in an area also utilized by man. Mountain caribou are occasional visitors to the park. Mountain lions, bobcats, and coyotes are present, although the first have been reduced greatly from their original numbers. The beaver, marmot, otter, marten, cony, and a host of smaller mammals are interesting and important members of the fauna. Among the birds, those that attract the greatest interest are the osprey, water ouzel, ptarmigan, Clark nutcracker, thrushes, and sparrows.
[Ill.u.s.tration: _Hileman photo._ BEARGRa.s.s]
IDEAL PLACE TO SEE AMERICAN INDIANS
With the exception of the Kootenais, few Indians ventured into the fastness of the park mountains before the coming of the white men. Yet so frequently did a large number of tribes use its trails for hunting and warfare, or camp in midsummer along its lakes and streams on the edge of the plains, that the park has an Indian story intertwined with its own that is unsurpa.s.sed in interest. Except for a few plateau Indians who had strong plains" characteristics because they once lived on the plains, all tribes were of that most interesting of Indian types, the plains Indian.
The earliest peoples inhabiting the northern Montana plains of which we have any record were apparently Snake Indians of Shoshonean stock.
Later Nez Perces, Flatheads, and Kootenais pushed eastward through pa.s.ses from the headwaters of the Columbia River system. Then came horses and firearms, and the whites themselves to set up an entirely different state of affairs in their hitherto relatively peaceful existence. First, a growing and expounding Siouan race, pressed forward also by an expanding irresistible Algonkian stock, occupied the high plains and pushed back its peoples behind the wall of mountains. These were the Crows from the south, the a.s.siniboins to the east. Lastly, armed with strategy and Hudson"s Bay Co. firearms, and given speed and range with horses, the dauntless Blackfeet came forth from their forests to become the terror of the north. They grew strong on the abundance of food and game on the Great Plains, and pushed the Crows beyond the Yellowstone River, until met by the forces of white soldiery and the tide of civilization.
Today the Blackfeet on the reservation adjoining the park on the east remain a pitiful but picturesque remnant of their former pride and glory. They have laid aside their former intense hostility to the whites and have reconciled themselves to the fate of irrepressible civilization. Dressed in colorful native costume, a few families of braves greet the park visitor at Glacier Park Station and Hotel. Here they sing, dance, and tell stories of their former greatness. In these are reflected in a measure the dignity, the n.o.bility, the haughtiness, and the savagery of one of the highest and most interesting of aboriginal American peoples.
REFERENCES
ALBRIGHT, HORACE M., and TAYLOR, FRANK J. Oh, Ranger! About the national parks.
BOWMAN, I. Forest Physiography. New York, 1911. Ill.u.s.trated; maps.
EATON, WALTER PRITCHARD. Boy Scouts in Glacier Park. 1918. 336 pages.
---- Sky-line Camps. 1922. 268 pp., ill.u.s.trated. A record of wanderings in the Northwestern Mountains from Glacier National Park to Crater Lake National Park in Oregon.
ELROD, Dr. MORTON J. Complete Guide to Glacier National Park. 1924.
208 pp.
FARIS, JOHN T. Roaming the Rockies. 1930. 333 pp., ill.u.s.trated. Farrar & Rinehart, New York City, Glacier National Park on pp. 42 to 80.
HOLTZ, MATHILDE EDITH, and BEMIS, KATHERINE ISABEL. Glacier National Park, Its Trails and Treasures. 1917. 262 pp., ill.u.s.trated.
JEFFERS, Le ROY. The Call of the Mountains. 1922. 282 pp., ill.u.s.trated.
Dodd, Mead & Co. Glacier National Park on pp. 35-39.
JOHNSON, C. Highways of Rocky Mountains. Mountains and Valleys in Montana, pp. 194-215. Ill.u.s.trated.
KANE, J. F. Picturesque America. 1935. 256 pp., ill.u.s.trated. Frederick Gumbrecht, Brooklyn, N. Y. Glacier National Park on pp. 147-169.
LAUT, AGNES C. The Blazed Trail of the Old Frontier. Robt. M. McBride & Co., New York, 1926.
---- Enchanted Trails of Glacier Park. Robt. M. McBride & Co., New York. 1926.
MARSHALL, L. Seeing America. Philadelphia, 1916. Ill.u.s.trated. Map.
Chapter XXIII, Among the American Alps, Glacier National Park, pp. 193-200.
McCLINTOCK, W. The Old North Trail. 539 pp., ill.u.s.trated, maps.
Macmillan Co. 1920.
---- Old Indian Trails, Houghton Mifflin Co. 1923.