Park History:

Arches National Park is located in Southeast Utah and covers an area of 73,378.98 acres; 114.65 square miles. This park was proclaimed a national monument on April 12th, 1929 by President Hoover. An after several boundary changes in 1938,1960, and 1969; on November 12th, 1971 President Nixon signed the proclamation making it a National Park.

The land was first discovered in the early 1800's and was deemed worthless because it was so dry and so not very appealing to settlers. But more modern prospectors have been attracted to the area by deposits of oil, natural gas, potash, uranium, and even some dry ranch farming.

Geology:

Arches National Park is famous for its natural arches and is home to over two hundred stone arches, which all are of the Entrada Sandstone. These features formed as a result of buried salt and gypsum that succeeded in pushing upward doming the overlying sedimentary rocks. This occurred along many northwest-southeast trending ridges caused by faulting of Precambrian rocks. The salt and gypsum in these ridges were then weathered out through many different processes.

The narrow fin shape that so many arches appear as were created as the salt cored anticlines formed. The salt and gypsum cored features broke along many joints. The joints in these rocks widened as rain dissolved minerals that held the rock together. Plant roots, soil moisture, and freeze and thaw all helped this process. The sides of these features began to cave in and at one point the two sides would meet and break causing just an arch of rock to be left behind (figure 1). These particular arches are of the upper part of the formation ( the coral colored dune sandstone). One of the parks most famous arch is the Delicate Arch. Here in Arches National Park the uplifted Entrada Sandstone eroded along parallel vertical joints, forming fins, and pedestals as well as arches.

Some neighboring National Parks include Canyonlands National Park, Zion National Park, Dinosaur National Monument, Bryce Canyon National Park, Capitol Reef National Park, and Natural Bridges National Monument. Because of the close proximity of some of the Parks these are often many similarities in there geology although they are not identical. Since Arches National Park is just a short distance from Canyonlands National Park they have many of the same sandstones. They both have the Cutler Formation of Permian age, the Triassic Wingate Sandstone, and the Jurassic Navajo Sandstone. As well as the Jurassic Entrada Sandstone, the Morrison Formation, and the Cretaceous Dakota Sandstone that are exposed in Arches National Park. Click here to see the stratigraphic column of Arches National Park.

Click here for the stratigraphic column in Word or PDF format.

References:

Chronic, Halka, 1989, Roadside Geology of Utah, Mountain Press Publishing Company, Missoula, Montana. pp 270-273.

Doelling, Hellmut H, 1985, Geology of Arches National Park, Utah Geological and Mineral Survey, Salt Lake City, Utah. pp 1-15.

Harris, Ann G., Tuttle, Esther 1974, Arches National Park, Kendall/Hunt Publishing Company, Debuque, Iowa. pp 58-65.

Pictures from the Arches National Park Web Site, National Park Service