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.
The Snake River meanders through the surprisingly flat valley called Jackson Hole.
Jackson Hole was settled around the turn of the century, initially by homesteaders.
John D. Rockefeller, Jr., donated more than 32,000 acres of valley land, which were added to Grand Teton National Park in 1950.
Local residents were divided over the park issue. Two local park proponents, Mardy and the late Olaus J. Murie, are shown at a 1949 annual council meeting of the Wilderness Society. The Muries advocated park enlargement.
Geologic forces have not always been subtle influences in the valley. Melting snow and heavy rains in June 1925 saturated a layer of clay sandwiched between sedimentary rock layers that form the north end of Sheep Mountain, near Kelly. An earthquake, probably, triggered an enormous landslide, and thousands of tons of debris raced down into the river, damming it and backing up a lake 5 miles long and 200 feet deep. Two years later the top 50 feet of the dam broke off and a wall of water rushed down through Kelly, leveling all buildings except the church and school. Six lives were lost, despite ample warning. The landslide scar on Sheep Mountain’s north end is more than 5,000 feet long and 2,500 feet wide. Geologists say that more of Sheep Mountain is perched to slide, given similar spring rainfall and an earthquake trigger.
The rise of the Teton Range and the corresponding sinking of Jackson Hole continues, although not at an even rate. The action continues by irregular crustal movements known as earthquakes. Geologist John D. Love, longtime interpreter of the dynamics of the Teton Range, feels that a major earthquake movement along the Teton fault, of as much as 20 feet, could happen at any time. The impact would be many more times severe than the landslide and ensuing flood at Kelly. But such things are not given to easy and precise prediction.
The Elk Herd
The Jackson Hole elk herd is free ranging and migratory. About half of its 15,000 elk winter on the National Elk Refuge. By midsummer, many graze on bunchgrass in high meadows near the Continental Divide, more than 110 kilometers (70 miles) to the north. Moving north in spring, the elk feed on succulent new growth of grasses and forbs in the sagebrush flats. Cow elk, pregnant since last fall, separate from the main herds to linger on calving grounds. Newborn elk hide in sagebrush or aspen cover while the cows feed. Elk tend to feed in the open in morning and evening, retreating to forest shade during the day. All summer they gain weight in preparation for winter. Full grown cows often exceed 230 kilograms (500 pounds). Bulls may stand 1.5 meters (5 feet) at the shoulder and weigh 405 kilograms (900 pounds). After their antlers drop off in March, bulls begin growing a new annual set. Antlers, furry nubbins in May, become velvet covered branches by July. By late August the velvet, which supplied blood and nutrients for rapid antler growth, hangs in tattered shreds as bull elk rub their antlers against flexible saplings. In September, mature bulls polish the velvet from their antlers and join the cows on their summer ranges. Then the dominant bull elk gather harems of 6 to 20 cows. These bulls establish and maintain dominance by displaying massive branched antlers, impressive bugling, chasing off less aggressive bulls, and occasional combat with other males. Fall migratory herds sometimes number 200 or more. Migration begins when the snow reaches a critical depth. It is a special experience to witness this exodus of elk streaming down the valley. Many elk return to winter on the National Elk Refuge and in the Gros Ventre drainage. Supplemental feeding is provided on the refuge to maintain the Jackson Hole herd because some two-thirds of its traditional winter range has been lost to development. The remaining habitat, and the elk hunt permitted by the law that added Jackson Hole to the national park, is cooperatively managed by the National Park Service and other Federal and State agencies to perpetuate and protect the majestic elk of this great herd.
Settling the Valley
Shoshone, Crow, Blackfeet, Gros Ventre, and other Native Americans hunted and picked berries in the valley in summer, but winter was unbearable. During the early 1800s, solitary mountain men trapped valley beaver, sometimes wintering through intense and deep snow. After the fur trade collapsed in 1840, occasional trappers and prospectors ventured into Jackson Hole. Well-known pioneers built temporary cabins. Jackson Hole was settled late in the frontier era, when limited technology, supply routes, and food storage made winter bearable. The first permanent settlers, John Holland and John Carnes, homesteaded north of the town of Jackson in 1884. Significant settlement came after 1900 as schools, post offices, and churches were built. Jackson, Wilson, Moran, and Kelly became the dominant communities. Getting supplies and mail into Jackson Hole was always difficult. Most supplies came from Idaho over rugged Teton Pass. Pack horses and supply wagons then faced the Snake River, often dangerous or impossible to cross. Menor’s Ferry, built at Moose in 1894 by William D. Menor, was a major crossing until replaced by a bridge in 1927. Ferries, and later bridges, at Wilson also improved valley transportation. Most valley homesteaders became cattle ranchers, grazing their herds on the public range and cultivating enough hay for winter feed. But the harsh climate and porous soils made ranching risky. When some ranchers recognized the value of scenery and wildlife, they began operating dude ranches and hunting lodges. In 1903, Ben Sheffield catered to wealthy hunters from his headquarters at Moran. In 1907, Louis Joy operated the first dude ranch in Jackson Hole, the JY. The age of tourism had begun.
A rodeo at the Elbo Ranch, which was located near Cottonwood Creek.
The Snake River cuts through moraines and exposes a vast rubble of glacial cobbles. An evening float trip offers an opportunity to view wildlife, a part of the river’s biotic richness.