Skyline Arch, Arches National Park, Utah Coffee Mug

"Skyline Arch, Arches National Park, Utah" by Catherine Sherman. One of the most popular geologic features in Arches National Park, Utah, is Skyline Arch, which is named for its prominence on the horizon. It's visible from many areas of the park and is a short, easy walk from the main road. Skyline Arch is a large natural sandstone arch. The arches in the park are formed as the result of erosion through weak parts of sandstone fins composed of Jurassic-age Entrada Sandstone. A large boulder fell out of Skyline Arch in 1940, roughly doubling the size of the opening by half. Boulders from the collapse remain, and can be seen below the arch today Arches National Park is a national park in eastern Utah, consisting of 76,680 acres. The park is adjacent to the Colorado River, 4 miles (6 km) north of Moab, Utah. More than 2,000 natural sandstone arches are located in the park, including the well-known Delicate Arch, as well as a variety of unique geological resources and formations. The park contains the highest density of natural arches in the world. According to the U.S. Geological Survey, elevations in the park range from 4,085 feet at the Visitor’s Center to 5,653 feet at Elephant Butte. Pennsylvanian (286 to 320 million years ago) through Cretaceous (66 million years ago) sedimentary rocks are exposed in Arches National Park, representing marine, nearshore, and continental depositional environments and the arches are mostly found within Jurassic-aged sandstone. Many of the geologic units found within Arches National Park can also be found throughout the southwestern United States.