| Natural Bridges National Monument | |
|---|---|
IUCN category V (protected landscape/seascape) | |
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| Location | San Juan County,Utah, United States |
| Coordinates | 37°36′05″N110°00′49″W / 37.6013829°N 110.0137437°W /37.6013829; -110.0137437[1] |
| Area | 7,636 acres (30.90 km2)[2] |
| Created | April 16, 1908 (1908-04-16) |
| Visitors | 101,843 (in 2016)[3] |
| Governing body | National Park Service |
| Website | Natural Bridges National Monument |
Natural Bridges National Monument is aU.S. National Monument located about 50 miles (80 km) northwest of theFour Corners boundary of southeastUtah, in thewestern United States, at the junction ofWhite Canyon and Armstrong Canyon, part of theColorado River drainage. It features the thirteenth largestnatural bridge in the world,[4] carved from the whitePermian sandstone of theCedar Mesa Formation that gives White Canyon its name.
The three bridges in the park are namedKachina,Owachomo, andSipapu (the largest), which are allHopi names. Anatural bridge is formed througherosion by water flowing in the stream bed of the canyon. During periods of flash floods, particularly, the stream undercuts the walls of rock that separate the meanders (or "goosenecks") of the stream until the rock wall within the meander is undercut and the meander is cut off and the new stream bed then flows underneath the bridge. Eventually, as erosion and gravity enlarge the bridge's opening, the bridge collapses under its own weight. There is evidence of at least two collapsed natural bridges within the Monument.
Humans have lived in the area around Natural Bridges since as early as 7500 BCE, as shown by rock art and stone tools found at nearby sites. Around 700 CE ancestors of modern Puebloan people moved to the site, constructing stone and mortar buildings and granaries. These structures share similarities with those found inMesa Verde National Park, which can be seen distantly, to the east, from theBears Ears on the park's eastern border. Like the people of Mesa Verde, the residents of Natural Bridges seem to have left the region around the year 1270.[5]
Europeans first visited the area in 1883 when gold prospector, Cass Hite followed White Canyon upstream, from the Colorado River, and found the bridges near the junction of White and Armstrong canyons. In 1904, theNational Geographic Magazine publicized the bridges and the area was designated a National Monument on April 16, 1908, by PresidentTheodore Roosevelt. It is Utah's first National Monument.
The Monument was nearly inaccessible for many decades as reflected by the visitor log kept by the Monument's superintendents. Reaching the site fromBlanding, Utah, the nearest settlement would take a three-day horseback ride. The park received little visitation until after the uranium boom of the 1950s, which resulted in the creation of new roads in the area, including modern-dayUtah State Route 95, which was paved in 1976.
Located within theColorado Plateau, the monument has three distinct bridges in White and Armstrong Canyons. These canyons were formed when theColorado River eroded thePermianCedar Mesa Sandstone. The Sipapu, Kachina, and Owachoma bridges were formed through rock decay,weathering anderosion, as water cut through narrow canyon walls. The monument is also the location of significantBiological soil crust. In places,Desert varnish darkens the lighter White Cedar Mesa Sandstone. The Monument's elevation ranges up to 6,500 feet (2,000 m).[6]
The main attractions are the natural bridges, accessible from the Bridge View Drive, which winds along the park and goes by all three bridges, and by hiking trails leading down to the bases of the bridges. There is also a campground and picnic areas and a visitor center within the park. Electricity in the park comes entirely froma large solar array near the visitor center.
In 2007, theInternational Dark-Sky Association named Natural Bridges the first International Dark-Sky Park, which is a designation that recognizes not only that the park has some of the darkest and clearest skies in all of the United States, but also that the park has made every effort to conserve the natural dark as a resource worthy of protection.[7][8] As of 2007[update], Natural Bridges has the onlynight sky monitored by the NPS Night Sky Team that rates a Class 2 on theBortle Dark-Sky Scale, giving it the darkest sky ever assessed.[7][9]
Horsecollar Ruin is anAncestral Puebloan ruin visible from an overlook a short hike from Bridge View Drive. The site was abandoned more than 700 years ago but is in a remarkable state of preservation, including an undisturbed rectangularkiva with the original roof and interior, and two granaries with unusual oval-shaped doors whose shape resembles horse collars (hence the site's name).
| Bridge | Height m (ft) | Span m (ft) | Width m (ft) | Thickness m (ft) |
|---|---|---|---|---|
| Owachomo | 32 (106) | 55 (180) | 8 (27) | 3 (9) |
| Sipapu | 67 (220) | 68 (225) | 9.5 (31) | 16 (53) |
| Kachina | 64 (210) | 62 (204) | 13 (44) | 28 (93) |
Animal species found in the National Monument include birds such as thepinyon jay,canyon wren, andwild turkey (which were reintroduced by the State of Utah to the table-lands above the Monument) and mammals like rabbits, pack rats,bobcats,coyotes, bears,mule deer, andmountain lion. The Monument's pygmy rattlesnakes have been the subject of occasional study; several lizard species common to southern Utah are abundant. In May 2006,KSL Newsradio reported a case ofplague found in dead field mice andchipmunks at Natural Bridges.[10]
Native plant species include willow,cottonwood,Douglas fir,ponderosa pine,pinyon pine,juniper, grasses, annuals, and perennials such as asters, penstemons, buckwheats, and Indian paintbrush, and various shrubs such as dwarf oaks, bayberry, manzanita, buffaloberry, rabbitbrush, black brush, brittle brush, Apache's plume, sage, yucca, andMormon tea. Invasive species include tumbleweeds, certain thistles, dandelions, and tamarisk.
Much of the Monument's ground is covered in communities ofcryptobiotic soil crusts, which prevents soil erosion and promotes the retention of soil nutrients.
Natural Bridges National Monument has a coldsemi-arid climate (Köppen:BSk) with cold winters and hot summers.
| Climate data for Natural Bridges National Monument, Utah, 1991–2020 normals, extremes 1965–present | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 60 (16) | 68 (20) | 77 (25) | 85 (29) | 93 (34) | 101 (38) | 103 (39) | 99 (37) | 96 (36) | 87 (31) | 78 (26) | 61 (16) | 103 (39) |
| Mean maximum °F (°C) | 50.6 (10.3) | 55.5 (13.1) | 66.9 (19.4) | 75.3 (24.1) | 84.7 (29.3) | 93.0 (33.9) | 96.5 (35.8) | 92.8 (33.8) | 88.2 (31.2) | 78.6 (25.9) | 63.2 (17.3) | 52.3 (11.3) | 96.8 (36.0) |
| Mean daily maximum °F (°C) | 39.3 (4.1) | 43.4 (6.3) | 52.8 (11.6) | 60.5 (15.8) | 71.0 (21.7) | 83.2 (28.4) | 88.6 (31.4) | 85.2 (29.6) | 77.1 (25.1) | 63.4 (17.4) | 50.2 (10.1) | 39.4 (4.1) | 62.8 (17.1) |
| Daily mean °F (°C) | 29.5 (−1.4) | 33.5 (0.8) | 41.4 (5.2) | 47.7 (8.7) | 57.5 (14.2) | 68.4 (20.2) | 74.3 (23.5) | 71.8 (22.1) | 64.1 (17.8) | 51.2 (10.7) | 39.5 (4.2) | 29.8 (−1.2) | 50.7 (10.4) |
| Mean daily minimum °F (°C) | 19.8 (−6.8) | 23.5 (−4.7) | 29.9 (−1.2) | 35.0 (1.7) | 44.0 (6.7) | 53.7 (12.1) | 60.1 (15.6) | 58.5 (14.7) | 51.1 (10.6) | 38.9 (3.8) | 28.8 (−1.8) | 20.1 (−6.6) | 38.6 (3.7) |
| Mean minimum °F (°C) | 5.1 (−14.9) | 10.0 (−12.2) | 17.1 (−8.3) | 22.0 (−5.6) | 30.5 (−0.8) | 40.1 (4.5) | 51.3 (10.7) | 50.2 (10.1) | 37.6 (3.1) | 24.0 (−4.4) | 12.9 (−10.6) | 5.4 (−14.8) | 2.6 (−16.3) |
| Record low °F (°C) | −11 (−24) | −13 (−25) | 6 (−14) | 6 (−14) | 20 (−7) | 30 (−1) | 41 (5) | 37 (3) | 27 (−3) | 6 (−14) | −2 (−19) | −14 (−26) | −14 (−26) |
| Averageprecipitation inches (mm) | 1.20 (30) | 0.83 (21) | 0.90 (23) | 0.72 (18) | 0.86 (22) | 0.38 (9.7) | 1.20 (30) | 1.42 (36) | 1.61 (41) | 1.15 (29) | 0.66 (17) | 1.05 (27) | 11.98 (304) |
| Average snowfall inches (cm) | 10.8 (27) | 5.5 (14) | 3.3 (8.4) | 1.6 (4.1) | 0.2 (0.51) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.6 (1.5) | 2.4 (6.1) | 7.6 (19) | 32.0 (81) |
| Average precipitation days(≥ 0.01 in) | 5.6 | 5.8 | 5.3 | 4.4 | 4.8 | 2.0 | 7.9 | 8.0 | 6.2 | 5.2 | 3.9 | 5.4 | 64.5 |
| Average snowy days(≥ 0.1 in) | 4.3 | 3.1 | 1.9 | 0.8 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.4 | 1.6 | 4.2 | 16.4 |
| Source:NOAA[11][12] | |||||||||||||
This article incorporatespublic domain material from websites or documents of theNational Park Service.
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