Grand Teton

Using This Handbook

Grand Teton National Park offers the startling and abrupt scenic grandeur of the Teton Range and the colorful history and natural history of the valley called Jackson Hole. Other major attractions include the Snake River, Jackson Lake, and surprisingly good opportunities for viewing wildlife, including such larger mammals as elk, moose, and pronghorns. This handbook is published in support of the National Park Service’s management policies and interpretive programs at the park. Part 1 introduces the park through the eyes of a beloved, longtime Jackson Hole resident, the nationally known conservationist Margaret E. (Mardy) Murie; Part 2 outlines the natural history, geology, and history of the mountains, valley, and river; and Part 3 presents concise travel guide and reference materials.

National Park Handbooks, compact introductions to the great natural and historic places administered by the National Park Service, are designed to promote understanding and enjoyment of the parks. Each is intended to be informative reading and a useful guide before, during, and after a park visit. More than 100 titles are in print. This is Handbook 122.

Library of Congress Cataloging in Publication Data

Main entry under title:

Grand Teton National Park.

(National Park handbook; 122)

Includes index

Supt. of Docs. no.: I 29.9/5:122

1. Grand Teton National Park (Wyo.)—Guide-books.

I. United States. National Park Service. Division of Publications.

II. Series: Handbook (United States. National Park Service. Division of Publications): 122.

F767.T3G7 1983 917.87’550433 83-600157

ISBN 0-912627-19-0

★GPO:1983—381-611/302 Reprint 1992

Part 1 Welcome to the Tetons 4

What Gratitude We Owe 7

By Margaret E. Murie

Part 2 Teton Country 22

The Mountains 25

The Valley 39

The Snake River 49

Wildlife and Wildflowers 59

Part 3 Guide and Adviser 70

Approaching Grand Teton 72

Map of the Park 74

Visitor Centers and Museum 76

Ranger-led Activities 78

Camping and Accommodations 79

Hiking 81

Backcountry Basics 82

Mountaineering 85

Boating and Floating 86

Fishing 89

Winter Activities 90

Management Concerns and Safety 92

Nearby Attractions 93

Armchair Explorations 94

Index 95

Part 1 Welcome to the Tetons

What Gratitude We Owe
By Margaret E. Murie

A bronze plaque at the doorway of the Maude Noble Cabin on the banks of the Snake River at Moose, Wyoming, recounts a notable meeting in 1923. It was a meeting at which “... Mr. Struthers Burt, Dr. Horace Carncross, Mr. John L. Eynon, Mr. J. R. Jones and Mr. Richard Winger, all residents of Jackson Hole, presented to Mr. Horace Albright, then Superintendent of Yellowstone National Park, a plan for setting aside a portion of Jackson Hole as a National Recreation Area for the use and enjoyment of the people of the United States.”

The plaque commemorates both the beginning and the end of a stormy period—from 1918 on into the 1950s—in Jackson Hole’s history. Those meeting at Miss Noble’s simple log cabin wanted to devise a way to save the valley’s natural beauty from commercial exploitation. They wanted it protected by a public agency. These few people recognized the need for safeguarding a meaningful segment of our country from the uses of commerce. Their idea did not catch on immediately.

In 1926 Horace Albright escorted John D. Rockefeller, Jr., and family into Jackson Hole, and a bright hope for this valley was born. Albright imparted to Rockefeller his vision of the whole valley as a national park. Rockefeller said nothing then but later admitted that Albright’s vision had set his own dreams in motion. A land company was formed to shield Rockefeller’s involvement, and it began to purchase valley parcels. Unaware of this, Congress voted to create a Grand Teton National Park in 1929. The park was only about one-third the size of today’s park, protecting only the immediate mountain range, and very little of the valley floor.

The 150 square miles of mostly mountain land then comprising Grand Teton National Park were not enough to safeguard the complete ecosystem of the valley. Through his agents, Rockefeller quietly purchased ranches and other private lands in upper Jackson Hole, where the soil was not good for ranching and some ranchers were having a hard time. In the avowed purpose of later turning them over to the Federal Government, Rockefeller was carrying out the aims of those who had met at Maude Noble’s cabin. And through all the following stormy years; through the establishment by proclamation of Franklin D. Roosevelt of the Jackson Hole National Monument to contain the Rockefeller-purchased lands; through all the opposition to it; through the eventual negotiated “peace” and the addition of all the monument lands to Grand Teton National Park by Congress in 1950, the Rockefeller family held to its goal of “a complete project.”

So now, after all the years and all the tumult, the cattlemen have their grazing rights on the national forest lands and the right to drift their cattle across national park lands to reach those permits: people still have their homes, dudes still come to the dude ranches. No one, Oldtimer or Newcomer, would now deny that the national park has vitalized the economy of the valley a thousandfold. These material results are quite obvious. Our problem now is not the amount of lands that are under State, private, or Federal jurisdiction, but whether or not we can keep our souls receptive to the message of peace these unspoiled lands offer us.

In my many years living in this valley called Jackson Hole, I have sometimes had half-waking fantasies about how such a very special place came to be. One could almost imagine that 50 or 60 million years ago some great force purposely set about to create a valley as beautiful as any valley could be. A step further into fantasy, one might imagine this great force saying: “Let us start, of course, with mountains. I shall raise up a block of granite from the Earth planet’s interior; over the centuries it will become a magnificent 14,000 feet high; time and the winds and waters will sculpt it. Looking across to it will be other hills and mountains, and glaciers will form the valley and then melt away and there will be waters and streams flowing through. But with only the winds and waters singing, it will be too quiet, it will not be alive, so there must be animals—mammals, birds, fish, frogs, toads, butterflies, and all the rest.”

Fritiof Fryxell, the first ranger naturalist of the park, has described the forming of these peaks: “With continued uplift came a stage when the passing air currents, in surmounting the block, were compelled to rise so high that their moisture condensed. Precipitation over the elevated region was thereby increased. The streams, ever gaining in volume and velocity, now flowed along with the fine enthusiasm and vigor of youth, and like a group of skilled artisans singing at their work, went about their business of sculpturing the range.”

Within this space the Creator must have intended to bring man in humility to his knees. Imagine traveling into the range from either south or north, toward its center. The peaks loom ever higher and steeper and more dramatic until, as Fryxell points out, with the 6.5 kilometers (4 miles) between Avalanche and Cascade, two of the canyons piercing the range, there stand in close ranks the South, Middle, and Grand Teton, Mt. Owen, Teewinot, Nez Perce, Cloudveil Dome, and many spires. These form an overwhelming Gothic assemblage of peaks, a concentrated and unforgettable mountain experience for anyone. And it all goes on, and on, and on, north or south, from there.

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.

Those “other mountains” are the Yellowstone Plateau to the north, the Absaroka, the Washakie, and Gros Ventre, merging southward into the Hoback and Snake River Ranges. It is immediately clear why the first mountain men called this type of valley a hole. As the Snake winds its way south from its source in a high mountain meadow in southern Yellowstone National Park, into and out of Jackson Lake, it is joined by other streams: Pacific Creek, the Buffalo River, the Gros Ventre. All are bordered by cottonwood and aspen and spruce and fir forests. The scene is one of infinite variety, and in summer it is aglow with wildflowers of every hue. When I first entered the valley in mid-July of 1927, I thought surely I was entering a fairyland.

We know that for many hundreds of years the Indians came to this valley to hunt and fish, but not to stay. They left the land nearly untouched. Then in the early 1800s came the mountain men to harvest the beaver. And the valley became the favorite of one David Jackson, for whom it was named by his fur trade partner, William Sublette, in 1829, 100 years before Grand Teton National Park was established.

The first white settlers came to the hole about 1884, settling first in the southern part of the valley. Grass grew there and hay could be raised. Cattle could live there. But it was a demanding environment. The settlers worked hard all summer and battled cold and deep snow in winter, feeding their stock by horse-drawn sleigh or on snowshoes. Much could be written about their survival techniques, but what interests us here in connection with the national park is that the life they led nurtured a bold and independent spirit. They believed in their “first rights” to this part of the world, and resisted anything threatening their independence and proprietary feelings. Most of what is now the national park was part of Teton National Forest in 1929, and cattlemen had grazing rights on the forest. Naturally they were flamingly opposed to anything that might change their privileges. This was the human background for the long drama of saving a good portion of Jackson Hole in its natural state, for the benefit of untold generations of people from all over the world.

Teton country was a part of the West where, thankfully, gold was not an issue. An oldtimer once left this notice on a Snake River gravel bar:

That left cattle as the only “gold,” with their owners ready to fight for what they considered their rights. The puzzling yet invigorating diversity among people is part of the long evolution of the human spirit. Jackson Hole was and still is a fascinating microcosm reflecting these diversities, and they all played roles in the long controversy that colors the history of this great national park.

One of the valley’s most famous residents, author Struthers Burt, once wrote: “I am afraid for my own country unless some help is given it—some wise direction. It is too beautiful and now too famous. Sometimes I dream of it unhappily.” When Burt wrote this there had irrupted at Jenny Lake and nearby, in front of the most impressive view of the main Teton peaks, a gasoline station, tourist cabins, a hot dog stand, a dance hall, and some rusting bodies of automobiles. No wonder he dreamed unhappily. But “some wise direction” did come. All the old blight along the highway has been removed and today there is a small ranger station, a tents-only campground, camper store, a small visitor center, and a small boat dock.

“The American public will not leave Jackson Hole alone; nor can we ask them to,” my husband, Olaus, wrote in 1943. “They will be coming in increasing numbers. In any situation involving large numbers of us, some regulation becomes a necessity, whether we like it or not.... It should be our ambition to assist all agencies to keep intact this one segment of America that we boast of as ‘the last of the Old West.’”

The Indians hunted and fished in this valley for all those hundreds of years and left no mark. The white man has been here less than one hundred and has left many marks. Today we have enlarged Grand Teton National Park, and the staff of the park now copes with a flow of nearly three million visitors each year.

On the edges and outskirts of the park, we still have the cloud of what Robert Righter describes in his history of the park as “the threats of subdivision and mammonism.” Righter bemoans the damper such activities can put on the human spirit otherwise inspired by the mountain range. “It seems important,” he says, “that future generations know that the Park commemorates not only the grandeur of nature but also the spirit of men acting for a noble cause; it is a park not of chance but of man’s design.”

Today, come to this national park with an open mind, open eyes, and an open heart. Leave your conveyance; walk the trails up into the canyons, around the lakes, into the hills, canoe on some of the lakes. Stand quietly at dusk by a beaver pond and you may see a moose or two or three, some ducks, a great blue heron, a pair of trumpeter swans. The list is long of what may be seen. And the list is equally long—or longer—of what may be heard if you stand quietly: the song of the Swainson’s thrush or the ruby-crowned kinglet, the raucous conversation of ravens, the chatter of pine squirrels, the rattling call of sandhill cranes.

Go by foot or canoe or kayak or on a quiet horse or, in winter, on cross-country skis. You will sense the full and busy and yet harmonious life pattern of the wild ones. It will come to mean something very special to you, for it is a balm and a benediction. It is a reminder of your primeval roots. Stand at the edge of some woods at night and hear a great-horned owl hooting; perhaps, if you are lucky, coyotes singing; or, after September 1, some bull elk bugling.

Be glad they are all still here. These quiet adventures will remain with you always. And think then, too, what might have happened in this valley, and what gratitude we owe a few.

Part 2 Teton Country

The Mountains

The tight concentration of tall peaks and pinnacles called the Cathedral Group has been described as “Chartres multiplied by six, a choir of shimmering granite spires soaring high above the nave and transept of the valley below.” Few fail to be impressed by these most scenic of mountains and by their staggering panoramic quality. Theodore Roosevelt, so often given to eloquence, called this “the most beautiful country in the world.” You may find yourself spending an inordinate amount of time just staring at the mountains.

The Tetons, being classic fault-block mountains, were originally mound-like, not jagged and spired. They were formed as the Earth cracked along a north-south line at the base of the mountains. As the Earth’s outer crust faulted under pressures deep within its mantle, the western block tilted upward and the eastern block sank. We speak about this mountain building in the past tense because, for us mortals, mountains symbolize eternity. But the action continues.

The Tetons are the youngest mountains in the Rocky Mountain system, but they are made out of some of the oldest rock in North America. The granitic gneisses and schists north and south of the central, highest peaks are some of the hardest and least porous rocks known. The rock of the Grand Teton is a younger granite. These qualities, and the accessibility of major peaks, attract technical rock climbers. The handholds are secure and the views breathtaking.

The geologic time scale is so vast we cannot imagine it. 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. Further proof that geologic processes continue.

The massive Teton Range contains a miniaturized world on a different time scale. The alpine world is a summer surprise because it offers flowering displays long after the valley show concludes for the season. Bloom time is delayed by ascending altitude: the rule of thumb is about 12 days delay per 1,000 feet. If you miss the yellow buttercups at lower elevations, climb higher and you may overtake their montane flowering in full bloom. Such are the rigors of alpine tundra life that here the flowers largely depend on wind for pollination, or on flies, rather than on bees. Bees cannot withstand the cold temperatures so common at these heights. The alpine insect explosion is brief, but ants, ladybugs and other beetles, and diminutive grasshoppers inhabit the alpine world. They make fast food for alpine-nesting birds, such as pipits, horned larks, white-crowned sparrows, and rosy finches that are desperately trying to nourish their hungry broods between the two edges of winter.

Specialized and severe, the alpine world is sparsely populated. Here eagles and weasels hunt for bird nestlings, marmots, pikas, pocket gophers, deer mice, and voles. The heartbeat of the extremely fragile tundra is slow by necessity. That any plants have adapted to this environment seems incredible. Yet alpine laurel fills rock crevices. Spring beauty blooms in pockets of soil. Mats of moss campion carpet slopes of shattered rock. White columbine nod in the wind shadows of larger rocks. Alpine sunflowers blaze like a galaxy of equal suns, their disproportionately large flowers awkwardly seated on abbreviated stalks.

The process of developing from bare rock to fully developed alpine vegetation might require thousands of years. By contrast, it is estimated that 100 years are required to form one inch of soil on the plains. On alpine heights the rate is many times slower. The first plants to colonize bare mountain rock might be lichens, multi-colored crustose plants adapted to extreme conditions. Lichens are tough. They grow on rocky outcrops near the South and North Poles. They also thrive on desert rocks that are too hot to touch. Lichen plants can first be dried in air and then in a dessicator and then exposed to 514°F for up to seven hours and yet, upon return to room temperatures, they will resume normal metabolism. And lichens regulate, to some extent, water flow at high elevations. On dry days their water content may be from two to ten percent of dry weight. On rainy days that may soar to more than 300 percent. Mats of lichen hold so much moisture that even a rise in barometric pressure may press some water out to resume its tortuous trip toward the Pacific Ocean.

Seven Teton peaks exceed 12,000 feet and one, the Grand Teton, pushes above 13,000 feet to 13,770 feet in elevation. At such heights, conditions support mountain glaciers. The Teton Glacier is one of about a dozen small alpine glaciers cradled in shaded east- or north-facing cirques among the high peaks. Teton Glacier occupies a spectacular cirque that faces east between the north face of the Grand and Mount Owen. It is partially fed by avalanches from the cliffs around it. Some of these cliffs are more than 3,000 feet high. The glacier’s terminus has retreated markedly since 1929, but the rate of loss was less between 1954 and 1963 than it was between 1929 and 1954. The mountain glaciers in today’s Tetons are not left over from the Ice Age. They began forming about 500 to 1,000 years ago, during the so-called Little Ice Age.

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.

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. Today we do not first see the Teton peaks across 160 kilometers (100 miles) of wilderness and then struggle to them afoot, on horseback, or by wagon. This spectacle may break upon us from the window of an airplane, or appear around a bend in the John D. Rockefeller, Jr. Memorial Parkway. The telescoping of time does not lessen the impact however. The range’s nearly even east base (see painting) is the best place from which to grasp its formation. Along this line the valley ends at an abrupt wall, with no foothills at the mountain’s base. These are sure signs of faulting, the elevation of a mountain block along a deep crack in the Earth’s crust. (See diagram.) 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.

Another unusual feature of the Teton Range is its divide, the division line at which water will flow off the mountains either west into the Teton River or east into the Snake. The Teton’s divide lies well below and to the west of the highest elevation. This is because the steeper east face caused water to flow off faster and thereby to cut deeper. These streams carved into the range and captured headwaters from less erosive western streams. Erosion and uplift continue competing in the range, which still rises through periodic earthquake activity.

 1. Mount Wister

 2. Shadow Peak

 3. South Teton

 4. Cloudveil Dome

 5. Nez Perce Peak

 6. Middle Teton

 7. Mount Owen

 8. Teewinot Mountain

 9. Rockchuck Peak

10. Mount St. John

11. The Jaw

12. Mount Woodring

13. Maidenform Peak

14. Mount Moran

15. Window Peak

16. Bivouac Peak

Forming and Shaping the Mountains

Uplift, erosion, and glaciation formed and shaped the Teton Range. Ice Age glaciers profoundly sculpted the horn-shaped peaks and gouged out the U-shaped valleys (photo and diagram). The present mountain glaciers were formed only 500 to 1,000 years ago.

The Teton Range is a textbook example of fault-block mountain building. The Teton Fault is about 40 miles long. Total vertical displacement was about 30,000 feet. Erosion has removed some 3,000 feet of material from Mount Moran, whose peak now stands about 6,600 feet above the valley floor. Most of the displacement took place with the dropping of the eastern block. The Range’s steep east face eroded faster than the western slope, which still carries some capping sedimentary layers.

Upthrown fault block

Gentle western slope

Teton Fault

Steep eastern face (Horn-shaped peaks and U-shaped valleys)

Valley floor filled with sediments

Down-dropped fault block

As massive Ice Age glaciers flowed through the Teton Range (below), moving ice changed the steep, V-shaped, water-cut valleys (above) into the distinctive U-shaped canyons seen today.

Teton Range today.

Teton Country Lakes

Tarn.

Jackson Lake.

With only a brief itinerary in the park you might leave Jackson Hole with a memory of the high peaks and just one lake, much the impression that postcards give. But there are dozens of lakes. Most must be sought off the highway behind fringes of trees or up a short reach of trail. Some nestle in the alpine heights. A checklist of park lakes based on how they were formed includes surprising variety. A few are oxbow lakes, cut off meanders of the Snake River. Two are real oldtimers, Emma Matilda and Two Ocean Lakes, formed about 30,000 years ago as the glaciers melted back. But most are new glistening souvenirs of the latest glacial advance that ended 8,000 years ago. This newest crop is readily identified by the morainal dams that back up each lake. Most easily recognized is the morainal dam of Jenny Lake. Unlike Jackson (large photo), Jenny, Bradley, Taggart, Leigh, and Phelps Lakes mark surfaces gouged by mountain glaciers. The many small ponds dotting the sagebrush flats, such as The Potholes, are not gouge scars, but pits. Here glacial outwash materials surrounded and buried small ice masses that later melted. The technical term for these depression ponds is kettle ponds, but The Potholes were named by a rancher, not a geologist. The Tetons’ highest lakes are called tarns (small photo). Bearing names such as Surprise, Grizzly Bear, Bear-paw, and Rimrock, these are diminutive versions of the glacial lakes at the foot of major canyons. They originate in ice-scoured pockets and are still forming under the small glaciers at the heads of highcountry canyons. The largest and most heavily fished lake is Jackson Lake. Cutthroat trout are native, but lake trout (Mackinaw) were introduced in the 19th century. The lake is 130 meters (425 feet) deep and 26 kilometers (16 miles) long. Jackson, a natural lake, was dammed before the park was established to store more water and control the Snake River for irrigation in Idaho. The Teton country’s lake and pond environment has benefited moose and ducks the most, but nearly all park denizens—vacationing Homo sapiens included—appreciate this aquatic resource. One species, the beaver, extends its appreciation by creating more ponds. Once nearly exterminated during the trapper’s era, beaver are now abundant here.

Mountain Climbing

Mountain climber.

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. Atop the 4,200-meter (13,770-foot) summit of the Grand Teton you stand taller than anything nearby. (A climbing permit is required. See “Mountaineering” in Part 3.)

This print, adapted from Leigh Ortenburger’s 1956 A Climber’s Guide to the Teton Range, shows the Grand Teton from the northeast. The four climbing routes indicated, and their first-ascent dates, are: 1 East Ridge (1929), 2 Northeast Couloir (1939), 3 North Face (1936), and 4 North Ridge (1931).

First climbed (officially) in 1898, the Grand was not climbed again until 1923. Since then, however, it has been one of the country’s most popular peaks.

The first ascent by a Jackson Hole woman, Geraldine Lucas, aged 59, is shown here in her triumphant moment in 1924.

Officially, the first party to climb the Grand Teton was the W. O. Owen party in 1898, although Hayden Survey members James Stevenson and Nathaniel Langford said they climbed it in 1872. Owen carried on a 30-year war to have history rewritten his way. He finally won—by act of the Wyoming legislature in 1929. Even a member of Owen’s party thought Stevenson and Langford had climbed it. And among Owen’s papers at his death was an 1899 letter, with route map, from a man who evidently climbed the Grand in 1893 with two soldiers. The man was not interested in particular credit for it.

The Mountain World

Above the tree limit and around snowfields and glaciers lies the alpine tundra. This fragile ecosystem challenges plant and animal survival with temperature extremes, high winds, a short growing season, frequent drought, and poor soil. Basic plant survival adaptations include dwarfism, oversize root systems, matting growth, succulent leaves or stems, and warmth-producing red pigments. Some high mountain plants are almost brown, not green, but perfectly alive. Dwarfism and matting keep plants snugged low to the ground where conditions are less severe than just a few centimeters higher. Animals tend to adapt to subalpine and alpine rigors by modifying their behavior rather than their structure. Exceptions include flightless grasshoppers and the pika’s fur-covered feet.

The summer alpine tundra provides insects, seeds, leaf crops, lichens, and fungi as wildlife food. For this short season animals are well supplied and may become conspicuous. Birds, with their advantage of flight, can cover vast areas quickly in the search for food. They can also readily change ecozones. A bird flying from alpine tundra down to a forested slope makes a journey between ecozones equivalent to migrating from above the Arctic Circle to northern Maine. Hawks and eagles, in a regular search for pikas or mice, can cover all of the Teton high peaks in 2 hours or less.

 1 Prairie falcon

 2 Pika

 3 Yellow-bellied marmot

 4 Cushion buckwheat

 5 Whitebark pine

 6 Subalpine fir krummholz

 7 Dwarf willow

 8 Pixie-cup lichen

 9 Black rosy finch

10 Alpine forget-me-not

11 Moss campion

12 Haircap moss

The Valley

With the Louisiana Purchase treaty signed, President Thomas Jefferson wanted to know what he had bought, so he sent the Lewis and Clark Expedition overland to the Pacific in 1803 to find out. On the return trip John Colter left the expedition along the Yellowstone River to stay in the West and join a trapping venture. He is considered the first white person to discover what is now Jackson Hole. Colter supposedly wandered through this high, mountain-encircled valley—trappers called such valleys holes—in the winter of 1807-1808. Colter was soon followed by other trappers, and 40 years later the trappers were followed by homesteaders. Several homesteaders became dude ranchers, and their dudes were followed by vacationers, who now number nearly three million each year.

The flatness of Jackson Hole comes as a surprise, considering that the Teton Range was formed by a fault-block process. You would expect a deep valley, but it has been filled repeatedly by rock debris transported by glaciers and their meltwaters. The Snake River does little cutting into the valley floor today. The flat areas above the river, called benches, were carved out when the river had the torrential force of glacial meltwater. The river’s north-south flow shows that the valley slopes southward. The valley also tilts westward, toward the fault that gave rise to the Teton Range. For reasons not fully known, the valley has sunk more than the mountains have risen. We know this because a sedimentary cap of rock atop Mount Moran—nearly 6,000 feet above the valley floor—was once connected to the same rock layer that now lies an estimated 24,000 feet below the valley surface.

The glacial material that fills the valley is largely quartzite rock rounded by tumbling in running water into softball- to basketball-sized cobbles, supplemented by gravel, sand, and silt. This rock came from long-vanished mountains to the northwest. The depth of the valleys cobble material is estimated at perhaps about 2,000 feet. This cobble material has been washed by glacial runoff so often that it lacks the clay content that is essential for the ground to retain water. Melting snow and rain rapidly percolate through, so that only grasses and other plants adapted to arid conditions can thrive in the valley’s coarse-textured soil. This is why sagebrush dominates the valley floor, except where streams and ponds provide enough water for willow bushes, spruce, and cottonwood trees. Lodgepole pines grow atop the recent glacial moraines that contain sufficient nutrients and clay, such as the one surrounding Jenny Lake.