Arches National Park

Arches National Park


Arches is a park of contradictions. Like pieces of fine pottery, the arches stand in fragile impermanence amid this rugged landscape. Bearing the creative imprint of time and the elements, they will, however, eventually surrender to the persuasive forces of gravity, ice and water. 

Geologic History

Born of seeping salt, the formation of the Arches began 300 million years ago in the Pennsylvanian Period, when saltwater from a nearby ocean flooded the area. The water then evaporated, leaving a deposit of salt. Repeated floodings and evaporations left deposits of salt that, over many millions of years, became thousands of feet thick. This layer of salt was then covered with debris that washed over it from nearby higher elevations. 

Over time, the debris was compressed into rock, in some places more than a mile thick. The enormous weight of this rock caused the salt, which is somewhat elastic, to be pushed away. In the process, domes, cavities, faults and anticlines (upfolds of the earth with cores of salt) were created. By the late Jurassic Period, about 135 million years ago, most of the movement of the salt had ceased. Eons passed as sedimentary deposits from nearby highlands continued to accumulate, forming thousands of additional feet of rock on top of the salt.

At some point between 60 million and 10 million years ago, the deposit of rock slowed and erosion began in earnest. It is estimated that during the last 10 million years, erosion has stripped away more than 5,000 vertical feet of rock. This process opened cracks in anticlines beneath the rock that were, in turn, dissolved by groundwater. With a weakened support system, the salt valleys began to collapse, setting the stage for the formation of the arches.

Entrada Sandstone is the basic material of the arches. The Entrada is a blend of numerous textures and densities fused together with varying amounts of natural calcium carbonate cement. The varying cement content is responsible for differential erosion—some areas resist erosion, while others do not—and results in fins, arches and sculpted rock.

Arches are often created from narrow sandstone walls called "fins," which have been isolated as a result of cracks in the earth and subsequent erosion. Water seeps into cracks in these fins, then freezes and expands, thus causing chunks of rock to fall off. The fin wall is narrower in some places than in others. Gravity and erosion help complete the formation of an arch.

Human History

Several individuals, over the course of decades, had a hand in establishing Arches as a national park. In the 1920s, prospector Alexander Ringhoffer traveled through the area and was so impressed with its wild beauty that he convinced Frank Wadleigh to come and see for himself. Wadleigh, the passenger traffic manager for the Denver and Rio Grande Western Railroad, was moved to contact Stephen T. Mather, the first director of the National Park Service (NPS). Mather then pushed for the creation of a national monument. In 1929, President Herbert Hoover signed an executive order that established Arches as a national monument.

The monument's size was diminished by President Dwight D. Eisenhower and then enlarged by President Lyndon Johnson to 114 square miles. In 1971, President Richard Nixon signed into law an act of Congress designating Arches as a national park. In 1998, the park's area was expanded by 3,140 acres to include Lost Spring Canyon, bringing the total to 119 square miles.

The Arches area, once frequented by hunting parties from the Fremont and ancestral Puebloan (Anasazi) peoples, has seen little permanent human habitation. One noteworthy exception is John Wesley Wolfe, a disabled Civil War veteran. Wolfe and his son, Fred, built Wolfe Ranch in 1898. Why they came to this place is unknown, but they did manage to maintain a small cattle operation for about 20 years. A weathered log cabin, a root cellar, a corral and a glimpse of the past are all that remain.

Desert Solitaire records one man's more recent experiences at Arches. The author, the late Edward Abbey, resided here during the 1950s while employed as a park ranger. A writer who described himself as "a man with the bark still on," Abbey gives a vivid account of how the park changed from season to season and brings to light subtleties of weather, rock formations and plant life that are unique to Arches National Park.