Yellowstone National Park is a U.S. National Park located in the states of Idaho, Montana, and Wyoming. Yellowstone is the first and oldest national park in the world and covers 3,470 square miles (8,980 kmē), mostly in the northwest corner of Wyoming. The park is famous for its various geysers, hot springs, and other geothermal features and is home to grizzly bears and wolves, and free-ranging herds of bison and elk. It is the core of the Greater Yellowstone Ecosystem, one of the largest intact temperate zone ecosystems remaining on the planet.
Long before any recorded human history in Yellowstone, a massive volcanic eruption spewed an immense volume of ash that covered all of the western U.S., much of the Midwest, northern Mexico and some areas of the eastern Pacific Coast. The eruption dwarfed that of Mt. St. Helens in 1980 and left a huge 70 kilometer long, 30 km wide caldera sitting over a huge magma chamber (see Geology section and Yellowstone Caldera). Yellowstone typically erupts every 600,000 years with the last event occurring 640,000 years ago. Its eruptions are the largest known to have ever occurred on Earth, producing drastic climate change in the aftermath. DNA evidence suggests the devastating results of these changes could have resulted in the worldwide population of humans falling to as little as 10,000 individuals.
The park was named for the yellow rocks seen in the Grand Canyon of the Yellowstone - a deep gash in the Yellowstone Plateau that was formed by floods during previous ice ages and by river erosion from the Yellowstone River.
The human history of the park dates back 12,000 years. It was known to the original natives as "Mitzi-a-dazi," the "River of Yellow Rocks," because of the hydrothermally-altered iron-containing yellow rocks in the Grand Canyon of the Yellowstone (many people incorrectly believe that the yellow color is from sulfur).
The Native Americans that hunted and fished in the Yellowstone region also utilized the significant amounts of obsidian found in the park to make cutting tools and weapons. In fact, arrowheads made of Yellowstone obsidian have been found as far away as the Mississippi Valley which strongly indicate that a regular obsidian trade existed between Yellowstone Native Americans and tribes further east.
In 1806 a member of the Lewis and Clark Expedition named John Colter left the Expedition to join a group of fur-trappers and was probably the first non-Native American to visit the region and make contact with the Native Americans there. After surviving wounds he suffered in a battle with Crow and Blackfoot tribes he gave a description of a place of "fire and brimstone" that was dismissed by most people as delirium.
Mountain man Jim Bridger later returned from an 1857 expedition to the park's area and told tales of boiling springs, spouting water, a mountain of glass and yellow rock. These reports were largely ignored, however, because Bridger was known for being a "spinner of yarns." Nonetheless his stories did arouse the interest of explorer and geologist F.V. Hayden who in 1859 started a two-year survey of the upper Missouri River region with Bridger as a guide and with United States Army surveyor W.F. Raynolds . The party was able to reach the approaches to the Yellowstone region but were not able to go any further due to heavy snows. The intervening American Civil War stopped all attempts to explore the region and Hayden would not be able to fulfill his mission to explore the area for another 11 years.
North Gate to Yellowstone Park at Gardiner, Montana which says "For the Benefit and Enjoyment of the People"
A party of Montanans then organized the Washburn-Langford-Doane Expedition headed by the surveyor-general of Montana Henry Washburn. Amongst the group was Nathaniel P. Langford who would later become known as "National Park" Langford and an Army detachment commanded by Lt. Gustavus Doane . The expedition spent about a month in 1870 exploring the region, collecting specimens and naming sites of interest.
In 1871 Hayden led a second, larger, expedition which was now government-sponsored to the Yellowstone region. He compiled a comprehensive report on Yellowstone which included photographs by W.H. Jackson and paintings by Thomas Moran. This report helped to convince the U.S. Congress to withdraw this region from public auction. Then on March 1, 1872 President Ulysses S. Grant signed a bill into law that created Yellowstone National Park.
Langford then served for five years without pay as the first superintendent of the park and was followed by several other superintendents (who worked with some minimal funding). The second superintendent was Philetus Norris who essentially volunteered for the position, after traveling through Yellowstone and witnessing its problems first-hand. During his tenure Congress finally began to give the superintendent a salary and minimal funds to operate the park. He used these monies to expand access to and further explore Yellowstone. Norris also hired Harry Yount (nicknamed "Rocky Mountain Harry") to control poaching and vandalism in the park. Today, Harry Yount is considered the very first national park ranger.
Three additional superintendents followed, but none proved effective in stopping the destruction of Yellowstone's natural resources.
This continued until 1886 when the Army was given the task of managing the park (see Fort Yellowstone ). The Army remained the steward of the park until control was given to a civilian corps of rangers under the newly-created National Park Service in 1916.
It was then made into an International Biosphere Reserve on October 26, 1976 and a World Heritage Site on September 8, 1978.
Satellite map with political borders that shows the location of Yellowstone in an interesting manner: It is on fire. From 1988.
A series of lightning-derived fires started to burn large portions of the park in July of the especially dry summer of 1988. Thousands of firefighters responded to the blaze in order to prevent human-built structures from succumbing to the flames. Controversially, however, no serious effort was made to completely extinguish the fires and they burned until the arrival of autumn rains. Ecologists argued that fire is part of the Yellowstone ecosystem and that not allowing the fires to run their course (as has been the practice in the past) will result in a choked, sick and decaying forest. In fact, relatively few megafauna in the park were killed by the fires and since the blaze many saplings have sprung-up on their own, old vistas were viewable once again and many previously unknown archaeological and geological sites of interest were found and cataloged by scientists. The National Park Service now has a policy of lighting smaller, controlled, "prescribed fires" to prevent another dangerous build-up of flammable materials.
In 2003 notable changes occurred in thermal activity resulting in the closure of certain areas of the park. Other findings included a bulge had appeared beneath Yellowstone Lake. On March 10, 2004 a biologist discovered 5 dead bison which had inhaled an apparent release of toxic geothermal gases. Shortly after in April of 2004 the park experienced an upsurge of earthquake activity. Scientists are undecided on how to interpret these recent events. The United States government responded by allocating more resources to monitor the caldera and asking visitors to remain on designated safe trails.
The continental divide of North America runs roughly diagonally through the south-western part of the park. The divide is a topographic ridgeline that bisects the continent between Pacific Ocean and Atlantic Ocean water drainages (the drainage from one third of the park is on the Pacific side of this divide).
The Continental Divide passes through Yellowstone.
For example, the Yellowstone River and the Snake River both have their origin close to each other in the park. However, the headwaters of the Snake River are on the west side of the continental divide and the headwaters of the Yellowstone River are on the east side of that divide. The result is that the waters of the Snake River head toward the Pacific Ocean and the waters of the Yellowstone head for the Atlantic Ocean (via the Gulf of Mexico).
The park sits on a high plateau which is, on average, 8000 feet (2,400 m) above sea level and is bounded on nearly all sides by mountain ranges of the Middle Rocky Mountains which range from 10,000 to 14,000 feet (3,000 to 4,300 m) in elevation. These ranges are the; Gallatin Range (to the north-west), Beartooth Mountains (to the north), Absaroka Mountains (to the east), Southern Absaroka Mountains (south-east corner), Teton Mountains (to the south - see Grand Teton National Park) and the Madison Range (to the west). The most prominent summit in the plateau is Mount Washburn at 10,243 feet (3,122 m).
Just outside of the south-western park border is the Island Park Caldera which is a plateau ringed by low hills. Beyond that is the Snake River Plains of southern Idaho which are covered by flood basalts and slope gently to the south-west (see Craters of the Moon National Monument).
The major feature of the Yellowstone Plateau is the Yellowstone Caldera; a very large caldera which has been nearly filled-in with volcanic debris and measures about 60 km long by about 50 km wide (40 by 30 miles). Within this caldera lies most of Yellowstone Lake which is the largest high-elevation lake in North America and two resurgent domes which are areas that are uplifting at a slightly faster rate than the rest of the plateau.
Columnar basalt near Tower Fall. Large floods of basalt and other lava types preceded mega-eruptions of super-heated ash and pumice.
Yellowstone is at the northeast tip of a smooth U-shaped curve through the mountains, which is now the Snake River Plain. This curved plain was created as the North American continent drifted across a stationary volcanic hot spot beneath the Earth's crust. This hot spot used to be near what is now Boise, Idaho, but North America has drifted at a rate of 4.5 centimetres a year in a south western direction, shifting the hot spot to its present location.
Yellowstone Caldera is the largest volcanic system in North America. It has been termed a "supervolcano" because the caldera was formed by exceptionally large explosive eruptions. It was created by a cataclysmic eruption that occurred 640,000 years ago that released 1000 cubic kilometers of ash, rock and pyroclastic materials (this was 800 times larger than Mount St. Helens' 1980 eruption), forming a crater nearly a kilometre deep and 70 by 40 km in size (45 by 25 miles) (the size of the caldera has been modified a bit since this time and has mostly been filled-in, however). The welded tuff geologic formation created by this eruption is called the Lava Creek Tuff . In addition to the last great eruptive cycle there were two other previous ones in the Yellowstone area.
Firehole River near Excelsior Geyser. The heat from the series of mega-eruptions continues to feed Yellowstone's many geysers, hot springs, and mud pots.
Each eruption is in fact a part of an eruptive cycle that climaxes with the collapse of the roof of a partially-emptied magma chamber. This creates a crater, called a caldera, and releases vast amounts of volcanic material (usually through fissures that ring the caldera). The time between cataclysmic eruptions in the Yellowstone area has ranged from 600,000 to 900,000 years but the small number of such climax eruptions can not be used to make a prediction for the time range for the next climax eruption.
The first and largest eruption, climaxed to the south west of the current park boundaries 2.2 million years ago and formed a caldera about 80 by 50 km in size (50 by 30 miles) and hundreds of metres deep after releasing 2,500 cubic kilometres of material (mostly ash, pumice and other pyroclastics). This caldera has been filled-in by subsequent eruptions and the geologic formation created by this eruption is called the Huckleberry Ridge Tuff . The second eruption, at 280 cubic km of material ejected, climaxed 1.2 million years ago and formed the much smaller Island Park Caldera and the geologic formation called the Mesa Falls Tuff . All three climax eruptions released vast amounts of ash that blanketed much of central North America and fell many hundreds of miles away (as far as California to the southwest; see Lake Tecopa ). The amount of ash and gases released into the atmosphere probably caused significant impacts to world weather patterns and led to the extinction of many species in at least North America. About 160,000 years ago a much smaller climax eruption occurred which formed a relatively small caldera that is now filled-in with the West Thumb of Yellowstone Lake.
Grand Canyon of the Yellowstone downstream from Lower Falls. The Grand Canyon of the Yellowstone was created by catastrophic ice-dam-break floods that exploited uplift-induced faults.
After the last major climax eruption 630,000 years ago until about 70,000 years ago, Yellowstone Caldera was nearly filled-in with periodic eruptions of rhyolitic lavas (example at Obsidian Cliffs ) and basaltic lavas (example at Sheepeaters Cliff ). But 150,000 years ago the floor of the plateau began to bulge-up again. Two areas in particular at the foci of the elliptically-shaped caldera are raising faster than the rest of the plateau. This differential in uplift has created two resurgent domes (Sour Creek dome and Mallard Lake dome ) which are uplifting at 15 millimetres a year while the rest of the caldera area of the plateau is uplifting at 12.5 mm/yr.
Preserved within Yellowstone are many geothermal features and some 10,000 hot springs and geysers, 62% of the planet's known total. The super-heated water that sustains these features comes from the same hot spot described above. The most famous geyser in the park, and perhaps the world, is Old Faithful Geyser (located in Upper Geyser Basin) but the park also contains the largest geyser in the world, Steamboat Geyser (in Norris Geyser Basin; see Geothermal areas of Yellowstone).
Biology and ecology
Main articles: Animals of Yellowstone, Greater Yellowstone Ecosystem
Map showing the ranges of the re-introduced packs
A controversial aspect of the park is the recent re-introduction of wolves into the park's ecosystem. For many years the wolves were hunted and harassed until they become locally extinct in the 1930s. The smaller cousin of the wolf, the coyote, then became the top predator of the park. However the coyote is not able to bring down any large animal in the park and the result of this lack of a top predator on these populations was a marked increase in lame and sick megafauna. Since the reintroduction of wolves in the late 1990s this trend has started to reverse. However, there is still fear among surrounding cattle ranchers and other livestock ranchers that the wolves will venture out of the park and prey on the much easier to kill domesticated animals. In fact this happens occasionally but the ranchers are compensated for their losses whenever they can prove that Yellowstone wolves were the cause of the livestock loss. The ranchers contend that it is difficult to prove that coyotes or wild dogs were the responsible parties. However, the endangered species status of introduced wolf packs has also been controversially suspended which makes it possible for ranchers to shoot and kill wolves that come close to their herds.
Bison graze near a hot spring
The relatively large American Bison (buffalo) populations that exist in the park are also a concern for ranchers who fear that the bison can transmit bovine diseases to their domesticated cousins. In fact about half of Yellowstone's bison have been exposed to brucellosis, a bacterial disease that came to North America with European cattle and may cause cattle to miscarry. The disease has little effect on park bison and no reported case of transmission from wild bison to a visitor or to domestic livestock has ever been filed. But since the possibility of contagion still exists, the State of Montana believes its "brucellosis-free" status may be jeopardized if bison are in proximity to cattle. Elk also carry the disease, but this popular game species is not considered a threat to livestock.
To combat the perceived threat, National Park personnel regularly harass bison herds back into the park when they venture outside of park borders. Animal rights activists state that is a cruel practice and that the possibility for disease transmission is not as great as some ranchers maintain. Ecologists also point out that the bison are just traveling to seasonal grazing areas that lie within the Greater Yellowstone Ecosystem that have been converted to cattle grazing (most of these areas are also within United States National Forests).
Yellowstone is one of the most popular national parks in the US. The park is unique in that it features multiple natural wonders all in the same park.
You can find geysers, hot springs, a grand canyon, forests, wilderness, wildlife and even a large lake inside the park. Due to the diversity of the features in the park, the list of activities for visitors is nearly endless. From backpacking to mountaineering, from kayaking to fishing, from sightseeing to watching bison, moose, and elk wandering into the parking lot of the visitor centers, most visitors enjoy a memorable experience in nature.
Due to the geothermal activities of the park, the odor of sulfur is common around the park. Visitors with respiratory difficulties should consult their doctors before visiting.
Wildland fire is common in the park. One major wildfire in 1988 burnt down much of the forest in the park. It would be wise to check the status of the park before planning a trip.
Yellowstone also advises visitors not to approach dangerous animals and to stay on designated safe trails to avoid falling into boiling liquids and inhaling toxic gas. In 2004, five bison were discovered dead from an apparent inhalation of toxic geothermal gases.
Visitors may stay right in the park, with a clear view of Old Faithful Geyser, at the park's Old Faithful Inn or in any of the many designated camping areas.
Geology of National Parks: Fifth Edition, Ann G. Harris, Esther Tuttle, Sherwood D. Tuttle (Iowa, Kendall/Hunt Publishing; 1997) ISBN 0-7872-5353-7
- National Park Service 
- Yellowstone Park Foundation 
Last updated: 05-13-2005 07:56:04