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Craters of the Moon is a National Monument and United States Preserve located in the Snake River Plain in central Idaho near Arco, Idaho. The features in this protected area are volcanic and represent one of the best preserved basalt flood areas in the continental United States.
The Monument was established on May 2, 1924. and in November 2000, a Presidential proclamation greatly expanded the Monument area. The National Park Service portions of the expanded Monument were designated as a National Preserve in August 2002. The area is managed cooperatively by the National Park Service and the Bureau of Land Management (BLM).
The Monument and Preserve encompass three major lava fields and 250,000 acres (1,000 km²) of sagebrush steppe grasslands to cover a total area of 714,727 acres (2,892 km²). All three lava fields lie along the Great Rift of Idaho, with some of the best examples of open rift cracks in the world. There are excellent examples of pahoehoe, slabby pahoehoe, shelly pahoehoe, spiny pahoehoe, aa, and block lava, as well as rafted blocks, tree molds, lava tubes, and many other volcanic features.
The Craters of the Moon lava field spreads across 618 square miles (1,600 km²) and is the largest young basaltic lava field in the lower 48 U.S. states. The Monument and Preserve contain more than 25 volcanic cones including outstanding examples of spatter cones. Sixty distinct lava flows form the Craters of the Moon Lava Field ranging in age from 15,000 to just 2,000 years old. The Kings Bowl and Wapi lava fields, both about 2,200 years old, are part of the National Preserve.
Craters of the Moon Lava Field reaches southeastward from the Pioneer Mountains. This lava field is the largest of several large and recent beds of lava that erupted from the 53 mile (85 km) long Great Rift volcanic zone; a line of weakness in the Earth's crust created by Basin and Range rifting. Together with fields from other fissures they make up the Lava Beds of Idaho, which in turn are located within the much larger Snake River Plain volcanic province.
The rugged landscape remains remote and undeveloped with only one paved road across the northern end. Located in south-central Idaho midway between Boise, Idaho and Yellowstone National Park, the monument includes 53,545 acres (217 km²) and the visitor center is 5900 feet (1800 m) above sea level. Combined U.S. Highway 20-26-93 cuts through the north-western part of the monument and provides access to it. The closest city is Arco, Idaho.
Total average precipitation in the Craters of the Moon area is between 15 to 20 inches (400 to 500 mm) per year and most of that is lost in cracks in the basalt, only to emerge later in springs and seeps in the walls of the Snake River Canyon. Older lava fields on the plain have been invaded by drought-resistant plants such as sagebrush while younger fields, such as Craters of the Moon, only have a seasonal and very sparse cover of vegetation. In fact from a distance this cover disappears almost entirely, giving an impression of utter black desolation. Repeated lava flows over the last 15,000 years has raised the land surface enough to expose it to the prevailing southwesterly winds, which help to keep the area dry. Together these conditions make life on the lava field difficult.
There is no archaeological evidence that Native Americans ever lived on the Craters of the Moon Lava Field. Northern Shoshone did create trails through the field during their Summer migrations from the Snake River to the Camas Praire, west of the lava field. Stone windbreaks at Indian Tunnel are among the most obvious signs of their temporary presence. A hunting and gathering culture, the Northern Shoshone pursued Wapiti, bears, American Bison, cougars, and Bighorn Sheep - all large game who no longer range the area.
White fur trappers avoided the lava field area below the Pioneer Mountains by following Indian trails. Early Caucasian pioneers who sought gold, affordable farm land to raise crops, or cheap ranch land to range cattle also avoided the lava fields. It seems that nobody stayed for long.
Pioneers traveling in wagon trains on the Oregon Trail in the 1850s and 1860s later used Indian trails that skirted the lava flows in what today is the northern part of the monument as part of an alternate route called Goodale's Cutoff. The cutoff was created to reduce the possibility of ambush by Shoshone warriors along the Snake River such as the one that occurred at Massacre Rocks (which today is memorialized in Idaho's Massacre Rocks State Park).
After gold was discovered in the Salmon River area of Idaho a group of emigrants persuaded an Illinois-born trapper and trader named Tim Goodale to lead them through the cutoff. A large wagon train left in July 1862 and met up with more wagons at Craters of the Moon Lava Field. Numbering 795 men and 300 women and children, the unusually large group was relatively unmolested during its journey and named the cutoff for their guide. Improvements to the cutoff such as adding a ferry to cross the Snake River made it into a popular alternate route of the Oregon Trail.
In 1879 two Arco, Idaho cattlemen named Arthur Ferris and J.W. Powell became the first known people to explore the lava field while they were investigating its possible use for grazing. They found it to be unsuitable and left, however.
United States Army Captain and western explorer B.L.E. Bonneville visited the lava field and other places in the West in the 19th century and wrote about his experiences in his diaries. Washington Irving later used Bonneville's diaries to write the Adventures of Captain Bonneville, saying this unnamed lava field is a place "where nothing meets the eye but a desolate and awful waste, where no grass grows nor water runs, and where nothing is to be seen but lava."
Israel Russell in 1901 and 1903 became the first geologist to study this area while surveying it for the United States Geological Survey (USGS). In 1910 geologist Samuel Paisley continued Russell's work and later became the monument's first custodian. Others followed and in time much of the mystery surrounding this and the other Lava Beds of Idaho was lifted.
The few Caucasians who visited the area in the 19th century created local legends that it looked like the surface of the Moon. Geologists Harold T. Sterns coined the name "Craters of the Moon" in 1923 while trying to convince the National Park Service to recommend protection of the area in a National Monument.
Robert Limbert, a sometime taxidermist, tanner and furrier from Boise, Idaho, explored the area, which he described as "practically unknown and unexplored, " in the 1920s after hearing stories from fur trappers about "strange things they had seen while ranging the region."
Limbert set out on his third and most ambitious foray to the area in 1924, this time with W.C. Cole and an Airedale Terrier to accompany him. Starting from Minidoka, Idaho they explored what is now the monument area from south to north passing Two Point Butte, Echo Crater, Big Craters, North Crater Flow, and out of the lava field through the Yellowstone Park and Lincoln Highway (now known as the Old Arco-Carey Road). Taking the dog along was a mistake, Limbert wrote, "for after three days' travel his feet were worn and bleeding."
A series of newspaper and magazine articles authored by Limbert were later published about this and previous treks, increasing public awareness of the area. The most famous of these was an article that appeared in a 1924 issue of National Geographic where he called the area "Craters of the Moon," helping to solidify the use of that name. In the article he had this to say about the cobalt blue of the Blue Dragon Flows:
In part due to Limbert's work, Craters of the Moon National Monument was proclaimed on May 2 the same year by U.S. President Calvin Coolidge to "preserve the unusual and weird volcanic formations." Since then the monument has been enlarged and in 1970 the United States Congress set aside a large part of it as Craters of the Moon Wilderness, protecting that part under the National Wilderness Preservation System.
Much later NASA visited the real Moon through the Apollo program and found that its surface does not closely resemble this part of Idaho. NASA astronauts discovered that real moon craters were almost all created by impacting meteorites while their namesakes on Earth were created by volcanic eruptions. One thing is very similar between the two places; they are both desolate. Apollo 12 astronauts, as a matter of fact, performed part of their training at Craters of the Moon Lava Field. There they learned how to look for and collect good rock specimens in an unfamiliar and harsh environment.
The monument was expanded in 2000 from 53,545 to 700,000 acres (217 to 2,800 km²) in order to encompass the entire Great Rift zone. The entire addition is called the BackcountryArea while the two older parts are called the Developed Area and Wilderness Area. Craters of the Moon National Monument and Preserve is co-managed by the National Park Service and the Bureau of Land Management.
Ample evidence has prompted geologists to theorize that the Snake River Plain is a volcanic province that was created by a series of cataclysmic caldera-forming eruptions which started about 15 million years ago (see supervolcano). A migrating hot spot thought to now exist under Yellowstone National Park has been implicated. Leftover heat from this hot spot was later liberated by Basin and Range associated rifting and created the many overlapping lava flows that make up the Lava Beds of Idaho. The largest rift zone is the appropriately named Great Rift and it is from this fissure system that Craters of the Moon Lava Field was created.
In spite of its fresh appearance, and according to Mel Kuntz and other USGS geologists, the oldest flows in the Craters of the Moon Lava Field are 15,000 years old and the youngest erupted about 2000 years ago. Nevertheless the volcanic fissures at Craters of the Moon are considered to be dormant, not extinct and are expected to erupt sometime during the next thousand years. Eruptions were dated using paleomagnetic and radiocarbon methods, which together give dates that are considered accurate to within 100 years.
There are eight major eruptive periods recognized in the Craters of the Moon Lava Field. Each period lasted about 1000 years or less and were separated by relatively quiet periods that lasted between a few hundred to more than 2000 years. Individual lava flows were up to 30 miles (50 km) long.
Geologists feared that a large earthquake that shook Borah Peak, Idaho's tallest mountain, in 1983 would restart volcanic activity at Craters of the Moon. It did not.
Years of cataloging by biologists and park rangers have recorded 375 species of plants, 2000 insects, 8 reptiles, 169 birds, 48 mammals, and even one amphibian (the Western Toad). Brown Bears once roamed this lava field but have long ago become locally extinct. Mule Deer, Bobcats, Great-horned Owls, Prairie Falcons, Golden-mantled Ground Squirrels are some examples. Traditional livestock grazing continues within the grass/shrublands administered by the BLM.
All plants and animals who live in and around Craters of the Moon are under great environmental stress due to constant dry winds and heat absorbing black lavas that tend to quickly sap water from living things. Summer soil temperatures often exceed 150 °F (65 °C) and plant cover is generally less than 5% on cinder cones and about 15% over the entire monument. Adaptation is therefore the secret to survival in this semi-arid harsh climate.
Water is usually only found deep inside holes at the bottom of blow-out craters. The black soil on and around cinder cones does not hold moisture for long, making it difficult for plants to establish themselves. Soil particles first develop from direct rock decomposition by lichens and typically collect in crevices in lava flows. Successively more complex plants then colonize the microhabitat created by the increasingly productive soil. The shaded north slopes of cinder cones provide more protection from direct sunlight and prevailing southwesterly winds and also have a more persistent snow cover (an important water source in early spring). These parts of cinder cones are therefore colonized by plants first.
Wildflowers add a bit of color to the dark and barren landscape from early May to late September (most are gone by late August). Moisture from snowmelt along with some rainfall in late Spring kick-starts the germination of annual plants, including wildflowers. Most of these plants complete their entire life cycle in the few months each year that moisture levels are good. The onset of Summer decreases the number of wildflowers and by Autumn only the tiny yellow flowers of sagebrush and rabbitbrush remain. Some wildflowers that grow in the area;
When wildflowers are not in bloom, most of the vegetation is found in semi-hidden pockets and consists of pine trees, cedars, junipers, and sagebrush. Strategies used by plants to cope with the adverse conditions include;
A common plant seen on the lava field is the Dwarf Buckweat, a 4 inch (100 mm) tall flowering plant with a 3 foot (1 m) wide root system. The root system monopolizes soil moisture in its immediate area, resulting in individual plants that are evenly spaced. Consequently, many visitors have asked park rangers if the buckwheat were systematically planted.
Gaps were sometimes left unmolested by lava but were nonetheless completely surrounded by it. These literal islands of habitat are called kipukas, a Hawaiian name used for older land surrounded by younger lava. Carey Kipuka is one such area in the southernmost part of the monument and is used as a benchmark to measure how plant cover has changed in less pristine parts of southern Idaho.
In May 1980 wildlife researcher Brad Griffith of the University of Idaho started a three year study to mark and count the Mule Deer in the monument. The National Park Service was concerned that the local herd might grow so large that it would damage its habitat. Griffith found that this group of Mule Deer has developed a totally unique drought evasion strategy for its species.
The deer arrive in the southern part of the monument mid-April each year once winter snows have melted away enough to allow for foraging. He found that by late summer plants in the area have already matured and dried to the point that they can no longer provide enough moisture to sustain the deer. In late July after about 12 days above 80 ° F (27 °C) and warm nights above 50° F (10 °C) the herd migrates 5 to 10 miles (8 to 16 km) north to the Pioneer Mountains to obtain water from free-flowing streams and shade themselves in aspen and Douglas-fir groves. Rain in late September prompts the herd to return to the monument to feed on bitterbrush until snow in November triggers them to migrate back to their winter range. This herd, therefore, has a dual summer range. It is also very productive with one of the highest fawn survival rates of any herd in the species.
Afternoon winds usually die down in the evening, prompting behavioral modifications in the herd. The deer avoid the dry wind by being more active at night when the wind is not blowing. In 1991 there was a three-year average of 420 Mule Deer.
A series of fissure vents, cinder cones, spatter cones, rafted blocks, and overlapping lava flows are accessible from the 7 mile (11 km) long Loop Drive. Wildflowers, shrubs, trees, and wild animals can be seen by hiking on one of the many trails in the monument or by just pulling over into one of the turn-offs. More rugged hiking opportunities are available in the Craters of the Moon Wilderness Area, the roadless southern and major part of the monument.
Ranger-led walks are available in summer and cover different topics such as wildlife, flowers, plants, or geology. Self-guiding tours and displays are available year-round and are easily accessible from the Loop Drive.
The caves are open to visitors but flashlights are needed except in Indian Tunnel and some form of head protection is highly recommended when exploring any of the caves. Lava tubes are created when the sides and surface of a lava flow hardens. If the fluid interior flows away a cave is left behind.
Craters of the Moon Campground has 52 sites - none of which can be reserved in advance. Camping facilities are basic but do include water, restrooms, charcoal grills, and trash containers. National Park Service rangers present evening programs at the campground amphitheater in the summer.
Backcountry hiking is available in the 68 square mile (180 km²) Craters of the Moon Wilderness. Only two trails enter the wilderness area and even those stop after a few miles (km). From there most hikers follow the Great Rift and explore its series of seldom-visited volcanic features. All overnight backcountry hikes require registration with a ranger. No drinking water is available in the backcountry and the dry climate quickly dehydrates hikers. Avoiding summer heat and winter cold are therefore recommended by rangers. Pets, camp fires, and all mechanized vehicles, including bicycles, are not allowed in the wilderness area.
Skiing is allowed on the Loop Drive after it is closed to traffic in late November due to snow drifts. Typically there are 18 inches (46 cm) of snow by January and 3 feet (90 cm) by March. Crosscountry skiing off of Loop Drive is allowed but may be dangerous due to sharp lava and hidden holes under the snow. Blizzards and other inclement weather may occur.
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