Teton Range

“ Shatter lines visible in many of the naked rock peaks show that the uplift was no smooth ride. The Tetons are very young mountains composed of very old rock. The range was thrust up about 9 million years ago. Young? Yes, when compared to the main Rocky Mountains, which rose 60 million years ago, and the Great Smoky Mountains, which have been above water more than 200 million years. The Teton Range’s crystalline rock is comparable to the 3-billion-year-old Allegheny Mountains core. This hard, stable rock, more than 300 times older than the mountains it forms, is a boon to climbers. ”

“ In Alaska Basin he can study the gently tilted layers of sandstone, limestone, and shale that once blanketed the entire Teton Range and can search for the fossils that help determine their age and decipher their history. From Hurricane Pass he can see how these even layers of sedimentary rock have been broken and displaced and how the older harder rocks that form the highest Teton peaks have been raised far above them along the Buck Mountain fault.
Of all those who explore the high country, it is the mountaineer who has perhaps the greatest opportunity to appreciate its geologic story. ”

“ As insignificant as these glaciers are compared to the colossal sheets that repeatedly lumbered through the Tetons and Jackson Hole, they slowly exact a toll on this hard rock, continuing to carve, etch, and abrade the range. They host life too: algae of a reddish hue that give rise to the phenomenon called watermelon snow.
28 The Teton Range
Any mountain range is the product of the struggle between uplift and erosion, but in few places are the results as clear as on the crest of the Teton Range. ”

“ This is the Teton Range, but it is not the whole picture. The glaciers that during the Ice Age came through the whole valley left lakes as a row of jewels at the feet of the peaks: Phelps, Taggart, Bradley, Jenny, Leigh, and then finally Jackson lakes, through which the Snake River travels for some 17 miles southward. From the lakes the flat glacial floor extends to meet the river in mid-valley and beyond to all the other beautiful, though not quite so spectacular, mountains and hills that form the north, east, and south walls of the valley known as Jackson Hole. ”

“ The second is the presence of efficient transporting agencies that move out and away from the mountains all rock debris that might otherwise bury the lower slopes.
The rocks making up most of the Teton Range are among the hardest, toughest, and least porous known. Therefore, they resist mechanical disintegration by temperature changes, ice, and water. They consist predominantly of minerals that are subject to very little chemical decay in the cold climate of the Tetons.
Absence of weak layers prevents breaking of the tough rock masses under their own weight. ”

“ To the southward, for fifty miles at least, nothing but igneous rocks can be seen. Toward the Tetons there is a series of high ridges, passing off from the main Teton Range toward the northeast, and varying in height from 9,500 to 10,500 feet above the sea, and from 1,000 to 1,800 feet above the valleys at their base.
The explorers ascended one of the high ridges, (not the highest, however,) and found it to be 1,650 feet above the valley at its foot. The northeast side is steep like a roof, the southwest breaking off abruptly. From the summit of this ridge, the view is grand in the extreme. ”

“ The Tetons are a still different kind—a fault block mountain range carved from a segment of the earth’s crust that has been uplifted along a fault. The Teton fault is approximately at the break in slope where the eastern foot of the range joins the flats at the west edge of Jackson Hole (see map inside back cover) , but in most places is concealed beneath glacial deposits and debris shed from the adjacent steep slopes. ”

“ The last Cretaceous sea still lingered in central Wyoming.
One bit of evidence (there are others) of the first Laramide mountain building west of the Tetons is a tremendous deposit of quartzite boulder debris (several hundred cubic miles in volume) derived from the Targhee uplift (fig. 42) . Nowhere is the uplift now exposed, but from the size, composition, and distribution of rock fragments that came from it, we know that it was north and west of the northern end of the present-day Teton Range. ”

“ Most of us simply refuse to imagine more than a few thousand years: we find anything greater too inhibiting. The Ice Age ended its major glacial action about 10,000 years ago, the beginning of the Holocene or the Recent, as early man wandered the glacial ice margins. But seven-eighths of Earth history are tied up in the Precambrian Period, the period of formation of the Teton Range’s 3.5-billion-year-old rocks. By contrast, just east of Jackson Hole—Thermopolis on your Wyoming highway map—there is now forming the youngest rock in the United States, travertine. ”

“ However, a few beds of “edgewise” conglomerate indicate the occurrence of sporadic storms. At this time, the sea covered all of Idaho and Montana and most of Wyoming (fig. 35B) and extended eastward 74 across the Dakotas to connect with shallow seas that covered the eastern United States. Soon after this maximum stage was reached slow uplift caused the sea to retreat gradually westward. The site of the Teton Range emerged above the waves, where, as far as is now known, it may have been exposed to erosion for nearly 70 million years (fig. 35C) . ”

“ The darker layers are rich in hornblende.
Irregular bodies of granite gneiss are interleaved with the layered gneisses in the northern part of the Teton Range. The granite gneiss is relatively coarse grained, streaky gray or pink, and composed principally of quartz, feldspar, biotite, and hornblende. It differs from enclosing layered gneisses in its coarser texture, lack of layering, and more uniform appearance. The dark minerals (biotite and 55 hornblende) are concentrated in thin discontinuous wisps that give the rock its streaky appearance. ”

“ On the west its waters flowed close beneath the great mountains which rose above it, but on the other three sides a belt of forest grew close to the water, and back of this belt, broad meadow lands, with groups of trees and low rounded clumps of willows, looked almost 121 like a park. Further to the eastward bare ridges rose higher and higher, forming the foot-hills of the main range, and still further to the east and southeast were massive mountains, more distant—and so seeming lower—than the Teton Range, but which were the Continental Divide. ”

“ Thus, six wholly distinct routes have been employed on this mountain, though only the traditional route and possibly the southwest ridge can be recommended to any except most expert alpinists.
Within the last decade other peaks in the range have come in for more and more attention. This they richly deserve, since from both a scenic and mountaineering standpoint many of them are worthy peers of the Grand Teton itself. Mount Moran, Mount Owen, Teewinot, Nez Perce, and the Middle Teton comprise a mountain assemblage which, for nobility of form and grandeur, would be difficult to equal anywhere. ”

“ The reason for these strange relations is that the hill is a fault scarp (see fig. 16A for a diagram) and the valley in which the town of Jackson is located was dropped 150 feet or more in the last 15,000 years.
On the skyline directly west of the turnout are horizontal and inclined layers of rocks. These once extended over the tops of the highest peaks but were worn away from some parts as the mountains rose. All along the range, trees grow only up to treeline (also called timberline—a general elevation above which trees do not grow) which here is about 10,500 feet above the sea. ”

“ This is probably because the moraines contain large amounts of clay and silt produced by the grinding action of the glaciers. Material of this type retains water much better and, because of the greater variety of chemical elements, is more fertile than the porous quartzite gravel and sand on the outwash plains.
Modern glaciers
About a dozen small rapidly dwindling glaciers exist today in shaded reentrants high in the Teton Range. They are probably vestiges of ice masses built up since the climatic optimum, during the so-called “Little Ice Age.” ”

“ The more ambitious hiker or mountaineer can seek out the inner recesses of the range and explore other facets of its geology. He can visit the jewel-like mountain lakes—Solitude, Holly, and Amphitheater are just a few—cradled in high remote basins left by the Ice Age glaciers. He can 21 get a closeup view of the Teton Glacier above Amphitheater Lake, or explore the Schoolroom Glacier, the tiny ice body below Hurricane Pass. ”

“ One of the most colorful flight routes into Jackson Hole is from the east, along the north flank of the Gros Ventre Mountains. For 40 miles this mountain range is bounded by broad parallel stripes of bright-red, pink, purple, gray, and brown rocks. Some crop out as cliffs or ridges, and others are badlands (bare unvegetated hills and valleys with steep slopes and abundant dry stream channels) . In places the soft beds have broken loose and flowed down slopes like giant varicolored masses of taffy. ”

“ The Tetons offer the adventurous some of North America’s most superb mountain climbing. The rock is very hard and mostly free of slides. Cracks and ledges abound for hand and foot holds. The mountains, rising sharply from the valley floor, are unusually accessible. No expedition is required just to reach the peak. All Teton peaks and spires have already been climbed. Many have been climbed by several routes. Together they offer an exceptional range of climbing difficulty, from a stiff uphill walk with little hand and foot work to technical climbs that challenge most experienced alpinists. ”

“ In traversing this loop one completely encircles the three Tetons and adjacent high peaks, viewing them from all sides, and learns to know them with an intimacy impossible to the visitor who contents himself with distant views.
MOUNTAIN CLIMBING
Among American climbers no range enjoys higher rank than the Tetons, and its growing fame abroad is evidenced by increasingly large numbers of foreign mountaineers who come here to climb. Leading mountaineers unhesitatingly rank many of the Teton climbs with the best in the Alps and other world-famous climbing centers. ”

“ The Three Tetons are the most noted historic peaks in the Rocky Mountains. The topography of the country is such that the highest peak, Grand Teton (13,691 feet) can be seen from a great distance and has long served as a landmark to trappers and pioneers. Unlike the mountains of that region, the Tetons are not hemmed in by foothills, but rise in bold relief from the surrounding plateau—the Grand Teton towering seven thousand feet above Jackson Lake, at its base. The range is but sixty miles long and lies some twenty-five miles south-west of Yellowstone Lake. ”

“ In several respects the flora of the Tetons is unique. The high mountains have constituted a barrier to plant migration which many forms could not cross; hence the range limit of a number of plants is found here. Representatives from north, south, east, and west are found in this general region, this being the limit, in many instances, of their distribution. There are many plants typical of the central Rockies, and a few known only to this range. Five life zones are recognized within the park, all occurring in a distance of less than 15 miles. ”

“ Wherever the loess occurs, it is marked by abundant modern coyote dens and badger burrows.
Figure 60. Air oblique view west toward the Teton Range, showing effects of Pinedale Glaciation on the landscape. Mt. Moran is at top left; the mountain front is broken by U-shaped valleys from which ice emerged into the area now occupied by Jackson Lake. The timbered area bordering Jackson Lake is the Jackson Lake moraine. One of the braided outlet channels breaching the Jackson Lake moraine can be seen crossing the outwash plain at the left center. ”

“ Other lakes formed in response to similar crustal movements in nearby places. One such lake, Grand Valley Lake (fig. 49) , formed about 25 miles southwest of Teewinot Lake; both contained sediments with nearly the same thickness, composition, appearance, age, and fossils. Although these two lakes are on opposite sides of the Snake River Range, the ancestral Snake River apparently flowed through a canyon previously cut across the range and provided a direct connection between them.
Development of mammals
The Cenozoic Era is known as the “Age of Mammals.” ”

“ The spectacular banded cliffs of the Wiggins Formation on both sides of Togwotee Pass (fig. 52) and farther north in the Absaroka Range are remnants of Oligocene volcanic conglomerate and tuff that once spread as a blanket 100 several thousand feet thick across eastern Jackson Hole and partially or completely buried the nearby older folded mountain ranges.
Figure 54. Obsidian, a volcanic glass less than 10 million years old, especially prized by Indians who used it for spear and arrow points and for tools. ”

“ Generations of sheep will occupy the same range. The Teton population, numbering between 100 and 125 animals, is wary because the sheep are hunted in fall on adjacent national forest lands. Hikers and climbers occasionally see them on the range’s east side, but you will not see bighorn sheep from your car except sometimes in the winter when they may move down into Jackson Hole. ”

“ At first glance the floor of Jackson Hole south of Signal Mountain seems flat, smooth, and featureless, except for the Snake River that cuts diagonally across it. Nevertheless, even the flats show a variety of land forms. The broad sage-covered areas, low isolated hills, and hummocky tree-studded ridges that form the foreground are all parts of the Teton landscape, and give us clues to the natural processes that shaped it. A critical look to the south discloses more strange things. We take for granted the fact that the sides of normal valleys slope inward toward a central major stream. ”