Grand Teton A Place Called Jackson Hole A Historic Resource Study of Grand Teton National Park

Over these seemingly changeless mountains, in endless succession, move the ephemeral colors of dawn and sunset and of noon and night, the shadows and sunlight, the garlands of clouds with which storms adorn the peaks, the misty rain-curtains of afternoon showers.

—Fritiof Fryxell, The Tetons: Interpretations of a Mountain Landscape

Teton Range, late summer. Michael Johnson

Fritiof Fryxell, a geologist and the park's first naturalist, not only appreciated the beauty of the Teton Range but also possessed the rare gift of creating vivid pictures with words. Not all appreciate the scenery of the mountains and Jackson Hole. One August morning, I overheard this conversation in the Moose Visitor Center at Grand Teton National Park. Walking past the lobby. I heard a brusque voice demand, "What's there to see in this park?" After the briefest hesitation, the ranger responded, "Well sir, along the Teton Park Road you can enjoy some fine views of the mountains, and ..." "What mountains?" the voice interrupted. Peeking into the lobby from the hall entrance, I saw a middle-aged man staring distrustfully at the nonplussed ranger. Not a cloud marred the deep blue sky; the Tetons were hard to miss. The visitor explained that he had left Yellowstone at sunrise, driving south into Grand Teton National Park. He had driven his recreational vehicle down Teton Park Road, which is situated at the very base of the mountain range. The ranger explained, "Well, sir, the mountains you drove past are the Teton Range." "That was it!" the man exclaimed. He turned abruptly and stalked out of the visitor center, muttering to himself. Obviously, he did not share Fryxell's vision.

Most visitors are awestruck by the remarkable alpine scenery in Jackson Hole, often sharing memories of their first view of the Teton Range from visits 20, 30, and even 40 years past. The Tetons are one of the most recognizable mountain ranges in the United States. So many descriptions of the peaks exist that the English language seems exhausted. "Jagged ridges," "blue-gray pyramids," "shimmering granite spires," "splendid sentinels" become trite, yet accurate, impressionistic images. Relatively small in area, the Teton Range is about 40 miles long and 10 miles wide. It extends from Teton Pass at the south, to the Berry Creek area near Yellowstone National Park. The mountains rise abruptly almost 7,000 feet above Jackson Hole on their eastern front, then slope more gently west into the Teton Basin in Idaho.

Jackson Hole is the other distinctive geographic feature in the area. (Mountain men coined the term "hole" to describe enclosed mountain valleys such as Jackson's.) This flat valley offers a remarkable contrast to the rugged spires of the Teton Range. Consisting of porous, cobbled soils covered with sagebrush, Jackson Hole is an upland valley surrounded by mountains and highlands. It is one of the largest such valleys in the Rocky Mountains, being 8 to 12 miles wide and 40 miles long.

The geographic position of the Teton Range and Jackson Hole is significant. Both are situated in the heart of the Rocky Mountains, the great chain of peaks dividing the North American continent in a north-south direction from Alaska to Mexico. Classified as one of the major natural regions of the continent, the Rocky Mountain cordillera is subdivided into three physiographic provinces. The Teton Range and Jackson Hole are in the Middle Rocky Mountain Province, characterized as "an assortment of different kinds of mountains with differing trends and semiarid intermontane basins." [1] The Jackson Hole area divides two very different geophysic provinces: the Wyoming Basin to the southeast and the Columbia River Plateau to the west.

The Tetons and Jackson Hole were part of the Wyoming Territory, which was established in 1868. In 1890, Wyoming became the 44th state to enter the Union. Wyoming is an Indian word meaning "large plains." Indeed, the state of Wyoming conjures images of stark buttes framed against an endless blue sky, with a shimmering gray-green sea of sagebrush in the foreground. Such landscapes are common, but first-time visitors are surprised to find that mountains dominate much of the state, offering a refreshing contrast of mountain and plain, forest and sage. The Laramie, Medicine Bow, Bighorn, Absaroka, and Wind River Ranges cut Wyoming into semiarid basins. [2] In the northeastern part of the state, mountain ranges such as the Teton, Absaroka, Wind River, Wyoming, Salt River, Snake River, Washakie, Gros Ventre, and Hoback dominate the landscape.

The Rocky Mountains appear to be an impassable barrier to travel from east to west. In fact, numerous passes penetrate the mountainous walls. Some provide relatively easy passage. Others are difficult routes. The Marias, Lolo, Lemhi, Union, and Teton Passes are significant breaches in the Rockies from Wyoming through Montana. However, none is more important than South Pass. Located approximately 100 miles southeast of Jackson Hole in the Wyoming Basin, South Pass provided an easy way through the Rocky Mountain barrier to lands west of the Continental Divide. The Oregon Trail crossed South Pass and, just another 50 miles away, the first transcontinental railroad linked the nation in 1869.

Watercourses also served as transportation routes to the western interior. The headwaters of several major river systems originate within a 100-mile radius of the Teton Range. The fabled Three Forks of the Missouri River are northwest of Jackson Hole in Montana. The Yellowstone River begins in the Teton Wilderness northeast of Jackson Hole, just east of the Continental Divide. The river feeds water into Yellowstone Lake, then exits Yellowstone National Park, after passing through the spectacular Grand Canyon of the Yellowstone. The Wind River has its source near Togwotee Pass. It flows southeast into the Wind River Valley where, at its confluence with the Popo-Agie (pronounced Papa-sha) River, it turns north abruptly and becomes the Bighorn River. The Bighorn empties eventually into the Yellowstone which, in turn, joins the Missouri River on the high plains. Across the Continental Divide, the headwaters of the Green River are nestled in the Wind River Mountains from whence it runs south to join the mighty Colorado River. The Snake River, named for the Shoshone or Snake Indians, flows through Jackson Hole. The waters of the Snake join the Columbia River, then empty into the Pacific Ocean. [3] Jackson Hole appears to be a serene valley anchored by the Teton Range, seemingly immovable and unyielding to the human eye. In terms of geologic time, however, the landscape is dynamic, ever changing. The Tetons are made of some of the oldest and hardest rocks on the earth, consisting of gneiss, schist, and granite. The mountains wage endless war against fierce weathering processes. Hard rocks resist forces such as extreme temperatures, and water and ice, but eventually submit. [4]

Comprehending geology lends understanding of the topography, hydrology, soils, vegetation, wildlife, and human history of Jackson Hole. Two geologic forces shaped the present topography of Jackson Hole and the Tetons: mountain building and glaciation. The Tetons are a classic fault block mountain range, created by the concurrent uplift and down-drop of blocks in the earth's crust. They rise along a series of faults that run in a north-south direction at the base of the range. On the east side of the Teton fault, another block of the earth's crust, Jackson Hole, dropped as the Tetons rose. J. D. Love and John D. Reed offer the best descriptions of the process comparing the vertical movements of the earth along the fault to the movements of giant trap doors:

They are both tilted blocks of the earth's crust that behaved like two adjoining giant trap doors hinged so that they would swing in opposite directions. The block on the west, which forms the Teton range, was hinged along the Idaho-Wyoming State line; the eastern edge was uplifted along a fault (a fracture along which displacement has occurred). This is why the highest peaks and steepest faces are near the east margin of the range. The hinge line of the eastern block, which forms Jackson Hole, was in the highlands to the east. The western edge of the block is down-dropped along the fault at the base of the Teton Range. As a consequence, the floor of Jackson Hole tilts westward toward the Tetons. [5]

Several points are worth noting about the Teton Range. Five to ten million years old, the Tetons are the youngest mountain range in the Rocky Mountains. In contrast, the great chain of the Rockies is 50 to 60 million years old. More important for people today, the Teton fault zone is active and, as a result, the range is still rising while the valley is sinking. Hence, the area is an active earthquake zone. Last, this dramatic rise of mountains explains, in part, the rugged beauty of the mountains today.

Glaciation is the other geologic force that molded the topography of Jackson Hole. Glaciers develop from tremendous accumulations of snow and are nothing more than large bodies of ice, snow, and earth that move by their own weight and gravitational pull. Ten different periods of glaciation have occurred in Jackson Hole over the last million years. Only two have left abundant evidence of their existence. The older of the two, called the Munger Glaciation, entered the valley 140,000 to 160,000 years ago. In this period, a huge glacier filled Jackson Hole with ice up to 4,000 feet thick. The more recent Pinedale Glaciation, which occurred in three phases, began 40,000 to 70,000 years ago and ended 12,000 to 15,000 years ago. [6]

The glaciers' handiwork is apparent in the mountains and valley today. The deep, U-shaped canyons and natural amphitheaters at the heads of canyons, called cirques, resulted from glaciers. Sapphire-colored lakes often form in these bowl-like basins called, logically, cirque lakes. Today, several small glaciers cling to the shaded recesses of the Tetons. These are reentrant glaciers, approximately 1,000 years old. Grinding out of the canyons of the Tetons glaciers created the prominent terminal and lateral moraines that form the basins and sides of the spectacular piedmont lakes—Jenny, Leigh, Bradley, Taggart, Phelps—along the base of the range. Other prominent moraines, such as Burned Ridge and Timbered Island, were created by glaciers in the valley. These forested ridges contrast sharply against the surrounding sagebrush flats, denoting the different composition of morainal soils. Northeast of Burned Ridge is an area known as the Potholes, a sage-covered plain riddled with crater-like depressions called kettles. These depressions were formed by chunks of ice left by receding glaciers and buried under the soil. The kettles appeared as the ice melted slowly over time. More important, as the glaciers melted and receded, torrents of water carried millions of quartzite cobbles from other nearby mountain ranges into the valley floor. Today. the sagebrush plant community dominates these glacial outwash plains.

The snow-covered Teton range as seen from Signal Mountain. Signal Mountain offers one of the finest vistas of the entire valley and surrounding mountains and highlands. National Park Service

People enjoy spectacular views of the Tetons from almost any location in the valley, but Signal Mountain offers one of the finest vistas of the entire valley and surrounding mountains and highlands. To the south, the Gros Ventre and Snake River Ranges enclose the southern end of the valley. Jackson Peak and Sheep Mountain, summits in the Gros Ventre Range, pierce the horizon. The Mount Leidy Highlands enclose the valley to the east. The Washakie Range and Pinyon Peak Highlands form the remainder of the eastern and northeastern boundary of the valley. From another vantage point, the Pitchstone Plateau, one can see beyond Jackson Lake to the north. The Teton Range to the west completes the encirclement of Jackson Hole.

Jackson Point Overlook is situated less than a mile below the summit of Signal Mountain. At this overlook, a panorama of alpine peaks unfolds before you. Here in 1878, the renowned pioneer photographer, William Henry Jackson, first photographed the Tetons from Jackson Hole. Unfortunately. he took few photographs of the valley or range "because of a smoky haziness that filled the air." Forest fires were responsible for the smoke, and the haze is apparent in his photographs. [7]

Far to the south, Buck Mountain stands out as one of the highest peaks at 11,938 feet. A sharp peak, visitors sometimes mistake it for the Grand Teton. The next peaks are Nez Perce—once called Howling Dog Peak—then Cloudveil Dome and the South Teton. The Grand Teton, Teewinot, and Mount Owen stand out on the horizon. At an elevation of 13,770 feet, the Grand Teton pierces the sky, a sharp alpine peak that anchors the range. From Signal Mountain, Teewinot Mountain and Mount Owen flank either side of the Grand Teton like courtiers. Teewinot is derived from a Shoshone word meaning "many pinnacles." To the right of the Grand Teton, Mount Owen is named for William O. "Billy" Owen, who made the first documented ascent of the Grand Teton in 1898. Mount Owen is the second highest peak in the Teton Range at 12,928 feet and offers one of the most difficult challenges for climbers. [8]

North of this splendid arrangement of peaks is Cascade Canyon, a deep U-shaped gorge yawning over Jenny Lake. A well-developed trail provides access into one of the most popular and beautiful canyons in the park, where a short (2.5 miles) hike rewards visitors with a view of Hidden Falls, a roaring torrent of water spilling over a cliff. Another steep half mile brings hikers to Inspiration Point, which affords a superb view of Jenny Lake and Jackson Hole. From here, sturdy hikers may forge ahead another six miles to Lake Solitude, a serene cirque lake located at the head of Cascade Canyon.

The north wall of Cascade Canyon is the southern side of Mount St. John, named for a geologist employed by the Hayden Surveys. Adjacent is Rockchuck Peak, named for yellow-bellied marmots, common residents of the rocky mountainsides and canyons. At Photographer's Point, Indian Paintbrush Canyon opens between rugged peaks, a textbook example of a glacial canyon. The mouth of Indian Paintbrush merges with Leigh Canyon, which is named for Beaver Dick Leigh, a late-nineteenth-century hunter and trapper who frequented the area. The canyons are separated by a smaller peak called Mount Woodring, named for the first superintendent of Grand Teton National Park.

Perhaps the most distinctive peak except for the Grand Teton, Mount Moran towers over Jackson Lake. The flat-topped mountain was named for Thomas Moran, the prominent landscape artist of the American West who participated in the Hayden Surveys. Skillet Glacier hangs on the east face of the mountain. Moran Canyon, north of the mountain, ends the central portion of the Teton Range. The mountains extend north for another 15 miles, where they merge with the ancient lava hills of Yellowstone. These peaks are less spectacular and, therefore, less well known. Yet, these hills and canyons are prime wilderness, unmarred by developed trails between Leigh and Webb Canyons.

From the summit of Signal Mountain, the Snake River can also be seen winding its way through Jackson Hole, coursing down a cottonwood and spruce-lined channel. Directly east of Signal Mountain is an abandoned channel of the Snake, a mute reminder that the landscape of Jackson Hole is dynamic. The Snake River is the valley's only drainage. It begins as a trickle in the Teton Wilderness, flows north into Yellowstone before looping south into the John D. Rockefeller Jr. Memorial Parkway. Enlarged by the Lewis River, the Snake flows into Jackson Lake. The river empties out of the lake at the Jackson Lake Dam and travels southwest, cutting the valley in half. It races out of Jackson Hole through the Snake River Canyon and enters the state of Idaho.

Looking at a map, three important tributaries feed the river from the east: Pacific Creek, Buffalo Fork, and the Gros Ventre River. Ditch Creek and the sprawling Spread Creek also enter from the east. Cottonwood Creek flows from Jenny Lake in the west, emptying into the Snake above Moose, Wyoming. South of the park, Flat Creek and Fish Creek are important tributaries, and the Hoback River joins the Snake just before it enters the Snake River Canyon.

Topographic maps show Jackson Hole's other distinctive features, such as Emma Matilda and Two Ocean Lakes, tucked in the hills between Buffalo Fork and Pacific Creek. Several buttes, possible remnants of ancient mountains scoured by glaciers, protrude from the valley floor—including Signal Mountain adjacent to Jackson Lake, Blacktail Butte in the central part of the valley, and East Gros Ventre and West Gros Ventre Buttes in the southern portion of the valley. In the park, Timbered Island and Burned Ridge stand out as prominent stands of lodgepole forest surrounded by gray-green sagebrush flats. The sagebrush flats in the valley seem inconspicuous, yet they are a distinct topographic element. The sage plain east of the Snake and north of Blacktail Butte is Antelope Flats. Baseline Flat is the plain located between the Teton Range and the Snake River. And, of course, the Potholes are situated northeast of Burned Ridge and west of the river.

The piedmont lakes at the base of the Teton Range offer some of the finest scenery in the region. These lakes formed inside the perimeters of glacial moraines. The lakes from south to north are Phelps, Taggart, Bradley, Jenny, String, Leigh, and Jackson. Located at the north end of the valley, Jackson Lake has been made a reservoir. The old Reclamation Service first constructed a log crib dam at the lake's outlet in 1906-1907. After it failed in 1910, the service built the present concrete dam, and added an earthen dike. By 1916, the project was complete. The dam raised the water level 39 feet, and increased the area of the lake from 17,100 to 25,540 acres. Its purpose was to provide irrigation water for farms in Idaho. Jackson Lake was added to the park in 1950.

Looking across the head of Cascade Canyon. Hiking the narrow Teton Range provides a quick transition from valley floor to treeless alpine zones. National Park Service

The soils of Jackson Hole and the Teton Range are divided into four primary groups: soils of mountains and foothills; soils of foothills, buttes, and glacial moraines; soils of terraces and alluvial fans; and soils of the floodplains. These four broad classifications can be further broken down into 11 types. In turn, surveyors identified 71 specific soils that are based on "the suitability and potential of a soil for specific uses." [9]

The soils of the mountains and foothills comprise 40 percent of the land surveyed in the 1970s by the Soil Conservation Service. Located at elevations between 6,000 and 13,000 feet, this terrain varies from rolling hills to steep mountains and is characterized by well-drained soils and rubble and rock outcrops. These soils are found in the Teton Range, the northeast portion of the park near Emma Matilda and Two Ocean Lakes, and Mount Reid near Jackson Lake.

Foothills, buttes, and glacial moraines are more limited in elevation, existing between 6,000 and 7,500 feet. These soils comprise 23 percent of the survey area. In the park, they are found in the benches at the base of the Teton Range, on buttes such as Blacktail and Signal Mountain, on glacial moraines such as Timbered Island, and on highlands in the northeast part of the park.

Alluvial fans and terraces comprise another general soil type and make up 21 percent of the survey area. Found at elevations between 6,000 and 7,000 feet, the terrain is both level and sloping. This zone is identified readily by its plant cover, consisting mostly of grass and sagebrush.

Soils of the floodplain occupy low terraces along major river drainages at elevations between 6,000 and 7,000 feet. The terrain is generally flat and the soils tend to be deep and poorly drained. This grouping comprises about 16 percent of the surveyed area. [10]

To a large degree, soils determine the distribution and variety of vegetation and wildlife, and are no less significant to humans. Today, ecologists recognize a surprising number of distinct zones in the Teton country, where distinct groupings of plants and wildlife can be identified. Known as biotic communities, they are defined as "any organized assemblage of populations of living organisms inhabiting a specific area or physical habitat." [11] In other words, a biotic community is a definable area where specific plants, insects, birds, and mammals will be found with some predictability subject to seasons and the time of day. For example, during the spring and fall, elk can be observed browsing in the sagebrush flats near Timbered Island, especially in the mornings and evenings.

Many biotic communities exist in Jackson Hole and the Teton Range. Most people do not think of lakes, rivers, streams, and ponds as habitat, but these areas make up the aquatic community, a rich mosaic of algae, aquatic plants, insects, fish, birds, and mammals. Bald eagles and ospreys depend on the fish in rivers and lakes for their food, while water is critical for the beaver's survival. The aquatic community comprises ten percent of the park.

The sagebrush community appears stark and barren, yet its look is deceiving. It is the largest biotic community in the park and hosts the most diverse plant communities. No less than 100 species of plants have been inventoried on the sagebrush flats. Meadow communities are dominated by sedges and grasses. Sedge meadows are usually found in low-lying areas, and often flood during the spring. Sedge-grass meadows are situated at higher elevations and are, therefore, drier. A high water table characterizes the shrub-swamp community. Shrubs such as willow, serviceberry, silverberry, and buffaloberry are typical species and important food sources for birds and mammals. Along watercourses, the dominant trees are cottonwood and blue spruce. The willow community is similar to the shrub-swamp, in that both grow where the water table is high and soil drainage poor. The best example of this habitat is Willow Flats, located near the Jackson Lake Dam. Moose are likely to be seen in these areas, since willow is a favorite food source and critical in winter. Groves of aspen cluster on dry hillsides and relatively flat areas, often between grasslands and coniferous forests. In the Rocky Mountains, aspen reproduce through shoots that sprout from the roots of trees.

Coniferous forests comprise three distinct biotic communities: lodgepole pine, Douglas fir, and spruce fir. Lodgepole pine is the most common evergreen in Jackson Hole, growing on the lower mountain slopes in the valley. Many of the lodgepole stands are estimated to be 80 to 100 years old. Mature trees become vulnerable to insect infestations and, predictably, the mountain pine bark beetle has attacked mature lodgepole forests, killing many trees in recent years. Other coniferous trees are limber pine, white bark pine, Colorado blue spruce, Engelmann spruce, subalpine fir, and Douglas fir.

Few visitors see the alpine tundra, a biotic community that begins at elevations of 9,500 to 10,000 feet and extends to the very summits of peaks. Vegetation is sparse or non-existent. Dwarfed plants cling to the ground in the most extreme climatic conditions. Yet, life exists here, for this is the home of dazzling wildflowers such as moss campion and the alpine forget-me-not, and birds and mammals use this zone during the summer, either migrating or hibernating in winter.

Historically, fire has had a significant impact on the biotic communities in the park. Over the last two decades, research has demonstrated conclusively that fires are an important element in forest succession, influence forest insect populations, and maintain diverse habitats. [12]

The diversity of plant communities explains the rich variety of wildlife in the Teton country. Today. 55 species of mammals inhabit parklands all or part of the year. Three hundred species of birds have been sighted in Jackson Hole. This is remarkable when one considers the impact of 100 years of settlement and development. For example, settlers, particularly cattlemen, exterminated the gray wolf in Jackson Hole after 1900. There were no bison left in Jackson Hole when the first homesteaders came in 1884, but they were reintroduced in the 1940s at the now defunct Jackson Hole Wildlife Park. In 1968, the herd of 15 animals broke through the fences and, since that time, the herd has been allowed to range freely. More recently, the grizzly bear has returned to historic ranges in the Jackson Hole. [13]

Climate is the final significant element of the environment of Jackson Hole. There are several variations of an old saying that there are two seasons in Jackson Hole—nine months of winter and three months of company. Indeed, the winters are long. The climate of Jackson Hole is classified as "cold-snowy-forest with humid winters." Although it varies from year to year, snowfall covers the ground in the valley from November through April. Most precipitation falls as snow. Moose, Wyoming, averages 23 inches of precipitation annually. During the winter, a mantle of snow 20 to 40 inches deep covers the valley floor. However, precipitation is extremely variable throughout the valley because of elevation and the rain shadow caused by the Teton Range. For example, between 1931 and 1960, Jackson recorded an annual mean snowfall of 76 inches compared to 154 inches at Moose from 1961 to 1981.

Winter is the dominant season. Spring and fall are short seasons, times of transition. Summers are short, with around 60 frost-free days per year. Although temperatures can break 90°F, summer highs seldom exceed the 80s. Summer evenings are cool and crisp, ranging in the 30s and 40s. Although the average minimum temperature at Moose in January and February is 4°F, sub-zero temperatures are common. Thermometers at Moose often dip to -20°F or -30°F. [14]

Jackson Hole represents a mosaic of biotic or plant communities shaped by geography. geologic forces, climate, and fire. The history of Jackson Hole is really the story of human interaction with the environment. That setting was probably much the same approximately 11,000 years ago, when the first humans entered Jackson Hole.

1. Charles Butler Hunt, Natural Regions of the United States and Canada (San Francisco: W.H. Freeman, 1974), p. 6.

2. Fritiof M. Fryxell, The Tetons, Interpretations of a Mountain Landscape (Berkeley: University of California Press, 1938), pp. 1-3.

3. Merrill J. Mattes, "Jackson Hole, Crossroads of the Western Fur Trade, 1807-1829," Pacific Northwest Quarterly 37 (1946): 88-89; and Ray Allen Billington, Westward Expansion: A History of the American Frontier, with the collaboration of James Blaine Hedges, 4th ed., rev. (New York: MacMillan, 1974), pp. 335-349.

4. Linda L. Olson and Tim Bywater, A Guide to Exploring Grand Teton National Park (Salt Lake City: RNM Press, 1991), pp. 24-30.

5. John David Love and John C. Reed Jr., Creation of the Teton Landscape; The Geologic Story of Grand Teton National Park, 1st ed., rev. (Moose, WY: Grand Teton Natural History Assn., 1971), p. 9.

6. Ibid., pp. 105-112; and Olson and Bywater, pp. 11-13.

7. Clarence S. Jackson, Picture Maker of the Old West: William H. Jackson (New York: Charles Scribner's Sons, 1947), p. 296.

8. Fryxell, Interpretations of a Mountain Landscape, pp. 11-12.

9. Jack F. Young, Soil Survey of Teton County, Wyoming, Grand Teton National Park Area (U.S. Department of Agriculture: Soil Conservation Service, 1982), pp. 3-11.

10. Ibid.

11. Tim W. Clark, Ecology of Jackson Hole Wyoming, A Primer (Salt Lake City, UT: Paragon Press, 1981), p. 40.

12. Ibid., pp. 40-73.

13. Bert and Meg Raynes, Birds of Jackson Hole, A Checklist (Moose WY: Grand Teton Natural History Assn., n.d.); Wildlife of Grand Teton (Moose, WY: Grand Teton Natural History Assn., n.d.); and William J. Barmore, et al., Natural Resources Management Plan, Grand Teton National Park (Moose, WY: National Park Service, 1986), pp. 111-121.

14. Richard A. Dirks and Brooks E. Martner, The Climate of Yellowstone and Grand Teton National Parks (U.S. Dept. of the Interior, National Park Service, Occasional Paper No. 6).