[3][4] The national park lies above an underground evaporite layer or salt bed, which is the main cause of the formation of the arches, spires, balanced rocks, sandstone fins, and eroded monoliths in the area.

This salt bed is thousands of feet thick in places and was deposited in the Paradox Basin of the Colorado Plateau some 300 million years ago (Mya) when a sea flowed into the region and eventually evaporated.

[11] Geological processes that occurred over 300 million years ago caused a salt bed to be deposited, which today lies beneath the landscape of Arches National Park.

Rock layers surrounding the edge of the salt bed continued to erode and shift into vertical sandstone walls called fins.

The Arches area was first brought to the attention of the National Park Service by Frank A. Wadleigh, passenger traffic manager of the Denver and Rio Grande Western Railroad.

Wadleigh, accompanied by railroad photographer George L. Beam, visited the area in September 1923 at the invitation of Alexander Ringhoffer, a Hungarian-born prospector living in Salt Valley.

Ringhoffer had written to the railroad to interest them in the tourist potential of a scenic area he had discovered the previous year with his two sons and a son-in-law, which he called the Devils Garden (known today as the Klondike Bluffs).

Wadleigh was impressed by what Ringhoffer showed him, and suggested to Park Service director Stephen T. Mather that the area be made a national monument.

The following year, additional support for the monument idea came from Laurence Gould, a University of Michigan graduate student (and future polar explorer) studying the geology of the nearby La Sal Mountains, who was shown the scenic area by local physician Dr. J. W. "Doc" Williams.

Designation of the area as a national monument was supported by the Park Service in 1926 but was resisted by President Calvin Coolidge's Interior Secretary, Hubert Work.

Finally, in April 1929, shortly after his inauguration, President Herbert Hoover signed a presidential proclamation creating the Arches National Monument, consisting of two comparatively small, disconnected sections.

The purpose of the reservation under the 1906 Antiquities Act was to protect the arches, spires, balanced rocks, and other sandstone formations for their scientific and educational value.

The name Arches was suggested by Frank Pinkely, superintendent of the Park Service's southwestern national monuments, following a visit to the Windows section in 1925.

In late 1938, President Franklin D. Roosevelt signed a proclamation that enlarged the Arches to protect additional scenic features and permit the development of facilities to promote tourism.

Two years later, President Richard Nixon signed legislation enacted by Congress, which significantly reduced the total area enclosed, but changed its status.

[38] The success of Abbey's book, as well as interest in adventure travel, has drawn many hikers, mountain bikers, and off-pavement driving enthusiasts to the area.

Permitted activities within the park include camping, hiking along designated trails, backpacking, canyoneering, rock climbing, bicycling, and driving along existing roads, both paved and unpaved.

[40] An abundance of wildlife occurs in Arches National Park, including spadefoot toads, antelope squirrels, scrub jays, peregrine falcons, many kinds of sparrows, red foxes, desert bighorn sheep, kangaroo rats, mule deers, cougars, midget faded rattlesnakes, yucca moths, western rattlesnakes, and collared lizards.

[41] A number of plant species are common in the park, including prickly pear cactus, Indian ricegrass, bunch grasses, cheatgrass, moss, liverworts, Utah juniper, Mormon tea, blackbrush, cliffrose, four-winged saltbrush, pinyon pine, evening primrose, sand verbena, yucca, and sacred datura.

The living soil layer readily absorbs and stores water, allowing more complex forms of plant life to grow in places with low precipitation levels.