Tuesday, February 26, 2013

West to east trending canyons provide

West to east trending canyons provide easier access by foot into the heart of the range as no vehicular roads traverse the range except at Teton Pass, which is south of the park. Carved by a combination of glacier activity as well as by numerous streams, the canyons are at their lowest point along the eastern margin of the range at Jackson Hole.[63] Sony Vaio VGN-NR31MR/S Battery Flowing from higher to lower elevations, the glaciers created more than a dozen U-shaped valleys throughout the range.[64] Cascade Canyon is sandwiched between Mount Owen and Teewinot Mountain to the south and Symmetry Spire to the north and is situated immediately west of Jenny Lake. North to south, Webb, Moran, Paintbrush, Cascade, Death and Granite Canyons slice through Teton Range. Sony Vaio VGN-NR31S/S Battery Jackson Hole is a 55 mi (89 km) long by 6 to 13 mi (9.7 to 21 km) wide graben valley with an average elevation of 6,800 ft (2,100 m), its lowest point is near the southern park boundary at 6,350 ft (1,940 m).[65] The valley sits east of the Teton Range and is vertically displaced downward 30,000 ft (9,100 m), Sony Vaio VGN-NR31SR/S Battery making the Teton Fault and its parallel twin on the east side of the valley normal faults with the Jackson Hole block being the hanging wall and the Teton Mountain block being the footwall.[66] Grand Teton National Park contains the major part of both blocks. Sony Vaio VGN-NR31Z/S Battery Erosion of the range provided sediment in the valley so the topographic relief is only 7,700 ft (2,300 m).[56] Jackson Hole is comparatively flat, with only a modest increase in altitude south to north, however a few isolated buttes such as Blacktail Butte and hills including Signal Mountain dot the valley floor.[62] Sony Vaio VGN-NR31Z/T Battery In addition to a few outcroppings, the Snake River has eroded terraces into Jackson Hole. Southeast of Jackson Lake, glacial depressions known as kettles are numerous. The kettles were formed when ice situated under gravel outwash from ice sheets melted as the glaciers retreated. Sony Vaio VGN-NR31ZR/S Battery Most of the lakes in the park were formed by glaciers and the largest of these lakes are located at the base of the Teton Range.[68] In the northern section of the park lies Jackson Lake, the largest lake in the park at 15 mi (24 km) in length, 5 mi (8.0 km) wide and 438 ft (134 m) deep.[52] Sony Vaio VGN-NR38E/S Battery Though Jackson Lake is natural, the Jackson Lake Dam was constructed at its outlet before the creation of the park and the lake level was raised almost 40 ft (12 m) consequently.[29] East of theJackson Lake Lodge lies Emma Matilda and Two Ocean Lakes. South of Jackson Lake, Leigh, Jenny, Bradley, Sony Vaio VGN-NR38M/S Battery Taggart and Phelps Lakes rest at the outlets of the canyons which lead into the Teton Range. Within the Teton Range, small alpine lakes incirques are common, and there are more than 100 scattered throughout the high country.[69] Lake Solitude, located at an elevation of 9,035 ft (2,754 m), is in a cirque at the head of the North Fork of Cascade Canyon. Sony Vaio VGN-NR38S/S Battery Other high altitude lakes can be found at over 10,000 ft (3,000 m) in elevation and a few, such as Icefloe Lake, remain ice clogged for much of the year.[70] The park is not noted for large waterfalls; however, 100-foot (30 m) high Hidden Falls just west of Jenny Lake is easy to reach after a short hike.[71] Sony Vaio VGN-NR38Z/S Battery From its headwaters on Two Ocean Plateau in Yellowstone National Park, the Snake River flows north to south through the park, entering Jackson Lake near the boundary of Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway.[72] The Snake River then flows through the spillways of the Jackson Lake Dam and from there southward through Jackson Hole, exiting the park just west of the Jackson Hole Airport.[72] Sony Vaio VGN-NR38Z/T Battery The largest lakes in the park all drain either directly or by tributary streams into the Snake River. Major tributaries which flow into the Snake River include Pacific Creek and Buffalo Fork near Moran and the Gros Ventre River at the southern border of the park. Through the comparatively level Jackson Hole valley, Sony Vaio VGN-NR31E/S Battery the Snake River descends an average of 19 ft (5.8 m) per mile (1.6 km), while other streams descending from the mountains to the east and west have higher gradients due to increased slope.[56] The Snake River creates braids and channels in sections where the gradients are lower and in steeper sections, erodes and undercuts the cobblestone terraces once deposited by glaciers. Sony VPCW11S1E/P Battery The major peaks of the Teton Range were carved into their current shapes by long vanished glaciers. Commencing 250,000–150,000 years ago, the Tetons went through several periods of glaciation with some areas of Jackson Hole covered by glaciers 2,000 ft (610 m) thick.[56][73] Sony VPCW11S1E/P Battery This heavy glaciation is unrelated to the uplift of the range itself and is instead part of a period of global cooling known as the Quaternary glaciation.[73] Beginning with the Buffalo Glaciation and followed by theBull Lake and then the Pinedale glaciation, which ended roughly 15,000 years ago, the landscape was greatly impacted by glacial activity. Sony VPCW11S1E/T Battery During the Pinedale glaciation, the landscape visible today was created as glaciers from the Yellowstone Plateau flowed south and formed Jackson Lake, while smaller glaciers descending from the Teton Range pushed rock moraines out from the canyons and left behind lakes near the base of the mountains.[73] Sony VPCW11S1E/W Battery The peaks themselves were carved into horns andarĂȘtes and the canyons were transformed from water-eroded V-shapes to glacier-carved U-shaped valleys.[56] Approximately a dozen glaciers currently exist in the park, but they are not ancient as they were all reestablished sometime between 1400 and 1850 AD during the Little Ice Age.[74] Sony VPCW12S1E/P Battery Of these more recent glaciers, the largest is Teton Glacier, which sits below the northeast face of Grand Teton. Teton Glacier is 3,500 ft (1,100 m) long and 1,100 ft (340 m) wide, and nearly surrounded by the tallest summits in the range.[73] Teton Glacier is also the best studied glacier in the range, and researchers concluded in 2005 that the glacier could disappear in 30 to 75 years.[66] Sony VPCW12S1E/T Battery West of the Cathedral Group near Hurricane Pass, Schoolroom Glacier is tiny but has well defined terminal and lateral moraines, a small proglacial lake and other typical glacier features in close proximity to each other. Grand Teton National Park has some of the most ancient rocks found in any U.S. Sony VAIO VGN-NR21E/S Battery National Park. The oldest rocks dated so far are 2,680 ± 12 million years old, though even older rocks are believed to exist in the park.[66] Formed during the Archean Eon (4 to 2.5 billion years ago), these metamorphic rocks include gneiss, schist and amphibolites.[66] Metamorphic rocks are the most common types found in the northern and southern sections of the Teton Range.[76] Sony VAIO VGN-NR21J/S Battery 2,545 million years ago, the metamorphic rocks were intruded by igneous granitic rocks, which are now visible in the central Tetons including Grand Teton and the nearby peaks.[66] The light colored granites of the central Teton Range contrast with the darker metamorphic gneiss found on the flanks of Mount Moran to the north.[76] Sony VAIO VGN-NR21S/S Battery Magma intrusions of diabase rocks 765 million years ago left dikes that can be seen on the east face of Mount Moran and Middle Teton.[66] Granite and pegmatite intrusions also worked their way into fissures in the older gneiss.[76] Precambrian rocks in Jackson Hole are buried deep under comparatively recent Tertiaryvolcanic and sedimentary deposits, as well as Pleistocene glacial deposits.[77] Sony VAIO VGN-NR21S/T Battery By the close of the Precambrian, the region was intermittently submerged under shallow seas, and for 500 million years various types of sedimentary rocks were formed.[76] During the Paleozoic (542 to 251 million years ago) sandstone, shale,limestone and dolomite were deposited.[78] Sony VAIO VGN-NR11Z/T Battery Though most of these sedimentary rocks have since eroded away from the central Teton Range, they are still evident on the northern, southern and western flanks of the range.[79] One notable exception is the sandstone Flathead Formation which continues to cap Mount Moran.[66][78] Sony VAIO VGN-NR11Z/S Battery Sedimentary layering of rocks in Alaska Basin, which is on the western border of Grand Teton National Park, chronicles a 120 million year period of sedimentary deposition.[78] Fossils found in the sedimentary rocks in the park include algae, brachiopods and trilobites.[79] Sedimentary deposition continued during the Mesozoic (250–65 million years ago) Sony VAIO VGN-NR11S/S Battery and the coalseams found in the sedimentary rock strata indicate the region was densely forested during that era.[80] Numerous coal seams of 5 to 10 ft (1.5 to 3.0 m) in thickness are interspersed with siltstone, claystone and other sedimentary rocks. During the late Cretaceous, a volcanic arc west of the region deposited fine grained ash that later formed into bentonite, an important mineral resource.[80] Sony VAIO VGN-NR11M/S Battery From the end of the Mesozoic to present, the region went through a series of uplifts and erosional sequences. Commencing 65 million years ago the Laramide orogeny was a period of mountain-building and erosion in western North America that created the ancestral Rocky Mountains.[80] Sony VAIO VGN-SR11M Battery This cycle of uplift and erosion left behind one of the most complete non-marine Cenozoic rock sequences found in North America.[81] Conglomerate rocks composed of quartzite and interspersed with mudstone and sandstones were deposited during erosion from a now vanished mountain range that existed to the northwest of the current Teton Range. Sony VAIO VGN-SR11MR Battery These deposits also have trace quantities of gold and mercury.[81] During the Eocene and Oligocene, volcanic eruptions from the ancestral Absaroka Range buried the region under various volcanic deposits.[81] Sedimentary basins developed in the region due to drop faulting, creating an ancestral Jackson Hole and by thePliocene (10 million years ago), Sony VAIO VGN-SR19VN Battery an ancestral Jackson Lake known as Teewinot Lake.[77] During the Quaternary, landslides, erosion and glacial activity deposited soils and rock debris throughout the Snake River valley of Jackson Hole and left behind terminal moraines which impound the current lakes. Sony  VGP-BPS13 Battery The most recent example of rapid alteration to the landscape occurred in 1925 just east of the park, when the Gros Ventre landslide was triggered by spring melt from a heavy snowpack as well as heavy rain. Grand Teton National Park and the surrounding region host over 1000 species of vascular plants.[83] Sony  VAIO VGP-BPS13A/B Battery With an altitude variance of over 7,000 ft (2,100 m), the park has a number of different ecological zones including alpine tundra, the Rocky Mountains subalpine zone where spruce-fir forests are dominant, and the valley floor, where a mixed conifer and deciduous forest zone occupies regions with better soils intermixed with sagebrush plains atop alluvial deposits.[84] Sony  VAIO VGP-BPS13B/B Battery Additionally, wetlands near some lakes and in the valley floor adjacent to rivers and streams cover large expanses, especially along the Snake River near Oxbow Bend near Moran and Willow Flats near the Jackson Lake Lodge.[85] Altitude, available soils, wildfire incidence,avalanches and human activities have a direct impact on the types of plant species in an immediate area.[86] Where these various niches overlap is known as an ecotone.[87] Sony  VAIO VGP-BPS13/S Battery The range of altitude in Grand Teton National Park impacts the types of plant species found at various elevations. In the alpine zone above the tree line, which in Grand Teton National Park is at approximately 10,000 ft (3,000 m), tundra conditions prevail.[88] In this treeless region, hundreds of species of grass, wildflower, moss and lichen are found.[89][90] Sony  VAIO VGP-BPS13A/S Battery In the subalpine region from the tree line to the base of the mountains, whitebark pine, limber pine, subalpine fir, andEngelmann spruce are dominant.[87] In the valley floor, lodgepole pine is most common but Rocky Mountain Douglas-fir, andblue spruce inhabit drier areas, while aspen, cottonwood, alder, and willow are more commonly found around lakes, streams and wetlands.[87] Sony  VAIO VGP-BPS13B/S Battery However, the tablelands above the Snake River channel are mostly sagebrush plains and in terms of acreage is the most widespread habitat in the park.[91] The sagebrush plains or flats have 100 species of grasses and wildflowers. Slightly more elevated sections of the plains of the northern sections of Jackson Hole form forest islands with one such obvious example being Timbered Island. Sony  VAIO VGP-BPS13/Q Battery In this ecotone, forested islands surrounded by sagebrush expanses provide shelter for various animal species during the day and nearby grasses for night time foraging. While the flora of Grand Teton National Park is generally healthy, the whitebark pine, and to a lesser degree the lodgepole pine, are considered at risk. In the case of the whitebark pine, Sony  VAIO VGP-BPS13A/Q Battery an invasive species of fungus known as white pine blister rust weakens the tree, making it more susceptible to destruction from endemic mountain pine beetles.[92] Whitebark pines generally thrive at elevations above 8,000 ft (2,400 m) and produce large seeds that are high in fat content and an important food source for various species such as the grizzly bear, red squirrel and Clark's nutcracker.[93] Sony  VAIO VGP-BPS13B/Q Battery The species is considered to be a keystone and a foundation species; keystone in that its "ecological role (is) disproportionately large relative to its abundance"[94] and foundation in that it has a paramount role that "defines ecosystem structure, function, and process".[94] Sony  VGP-BPS21 Battery Whitebark pine has generally had a lower incidence of blister rust infection throughout the Greater Yellowstone Ecosystem than in other regions such as Glacier National Park and the Cascade Range. The incidence of blister rust on whitebark pines in Yellowstone National Park is slightly lower than in Grand Teton.[93] Sony  VGP-BPS21A Battery Though blister rust is not in itself the cause of increased mortality, its weakening effect on trees allows native pine beetles to more easily infest the trees, increasing mortality. While general practice in National Parks is to allow nature to take its course, the alarming trend of increased disease and mortality of the vital whitebark pine trees has sparked a collaborative effort amongst various government entities to intervene to protect the species. Sony  VGP-BPS21B Battery Sixty-one species of mammals have been recorded in Grand Teton National Park.[91] This includes the gray wolf, which had been extirpated from the region by the early 1900s but migrated into the Grand Teton National Park from adjacent Yellowstone National Park after the species had been reintroduced there.[95] Sony  VGP-BPS21/S Battery The re-establishment of the wolves has ensured that every indigenous mammal species now exists in the park.[96] In addition to gray wolves, another 17 species of carnivores reside within Grand Teton National Park including grizzlies and the more commonly seen American black bear. Sony  VGP-BPS21A/b Battery Relatively common sightings of coyote, river otter, marten and badger and occasional sightings of mountain lion, lynx and wolverine are reported annually.[91] A number of rodent species exist including yellow-bellied marmot, least chipmunk, muskrat, beaver,Uinta ground squirrel, pika, snowshoe hare, porcupine, and six species of bats.[91] Sony VGP-BPS26 Battery Of the larger mammals the most common are elk, which exist in the thousands.[97] Their migration route between the National Elk Refuge and Yellowstone National Park is through Grand Teton National Park, so while easily seen anytime of the year, they are most numerous in the spring and fall. Sony VGP-BPL26 Battery Other ungulates include bison and pronghorn—the fastest land mammal in the western hemisphere—which are found throughout Jackson Hole as are moose, which tend to stay near waterways and wetlands.[91] Between 100–125 bighorn sheep dwell in the alpine and rocky zones of the peaks. Sony VGP-BPS26A Battery Over 300 species of birds have been sighted in the park including the calliope hummingbird, the smallest bird species in North America, as well as trumpeter swans, which is North America's largest waterfowl.[99] In addition to trumpeter swans, another 30 species of waterfowl have been recorded including blue-winged teal, common merganser, Sony VGP-BPS22 Battery American wigeon and the colorful but reclusive harlequin duck which is occasionally spotted in Cascade Canyon.[100] Both bald and golden eagles and other birds of prey such as the osprey, red-tailed hawk, American kestrel and occasional sightings of peregrine falcon have been reported.[101] Sony VGP-BPL22 Battery Of the 14 species of owls reported, the most common is the great horned owl, though the boreal owl andgreat grey owl are also seen occasionally.[101] A dozen species of woodpeckers have been reported, as have a similar number of species of warblers, plovers and gulls.[101] Sony VGP-BPS22A Battery The vocal and gregarious black-billed magpie frequents campgrounds whileSteller's jay and Clark's nutcracker are found in the backcountry. The sage covered plains of Jackson Hole are favored areas for sage grouse, Brewer's sparrow and sage thrashers, while the wetlands are frequented by great blue heron, Sony VAIO PCG-3B1M Battery

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