Environment Planet Earth 10 Mind-Boggling Facts About Arches National Park Discover the park's unique history and unexpected biodiversity. By Emily Rhode Emily Rhode Writer Dickinson College Arcadia University Emily Rhode is a science writer, communicator, and educator with over 20 years of experience working with students, scientists, and government experts to help make science more accessible and engaging. She holds a B.S. in Environmental Science and an M.Ed. in Secondary Science Education. Learn about our editorial process Updated July 15, 2021 Fact checked by Elizabeth MacLennan Fact checked by Elizabeth MacLennan University of Tennessee Elizabeth MacLennan is a fact checker and expert on climate change. Learn about our fact checking process Share Twitter Pinterest Email Delicate Arch glows in the light of sunset at Arches National Park. Mark Brodkin Photography / Getty Images Planet Earth Outdoors Weather Conservation Arches National Park is home to some of the most striking red rock formations in the world. Established as Arches National Monument in 1929 and later as a national park in 1971, Arches spans 119 square miles of southeastern Utah just outside of Moab. Over 1.5 million visitors on average come through the gates to see the 65 million-year-old sandstone arches, hoodoos, and canyons formed by the forces of water, wind, and temperature change. What was once the home of numerous indigenous tribes, the land now known as Arches National Park offers numerous hiking trails, panoramic views, and archaeological sites to visit and explore. But be careful where you walk in this delicate landscape. The high desert environment features plants and animals adapted to living in extreme conditions, as well as some organisms like biological crusts that are not only alive, but are an essential part of the ecosystem of Arches. Here are just a few of the amazing facts about this geologic and historical treasure of a park. It Has the Highest Concentration of Natural Stone Arches in the World Double Arch is one of the more popular arches to visit at the park. Angela Dukich / EyeEm / Getty Images The national park was named after the most prominent features in the desert landscape. With just around 2,000 documented arches, the park’s geology is constantly changing. Extreme environmental conditions create fractures and holes in the rocks that will someday become new arches to be discovered by park rangers or maybe even the tourist turned amateur geologist just passing through. There Are Four Main Categories of Arches Found at the Park Geologists have identified four distinct categories of arches based on how they were formed or what shape they are. The first type, cliff wall arches, occur right next to rock walls and are often the hardest type of arches to see. By contrast, free-standing arches can most obviously be identified as classic arches. Hard to reach pothole arches are formed when a small pit on top of rock meets in the middle with an opening on the side of a rock wall. And finally, natural bridges can be found spanning stream channels and are the least common type of arch at the park. The Entire Park Used to Be Under Water What is now a dry seabed was once a shallow inland sea. When the seawater retreated, it left behind sand that the wind formed into dunes. Those dunes petrified or turned into the rock that forms the park we know today. Water continues to mold the landscape of arches through erosion. The Soil Here Is Alive Biological soil is full of living organisms that help prevent erosion. John Elk / Getty Images Biological soil crust, also known as cryptobiotic crust, is made up of lichen, mosses, green algae, fungi, and cyanobacteria. One of Earth’s oldest living organisms, cyanobacteria help form the soil and generate oxygen. The biological crust remains dormant during the dry parts of the year and only moves around when wet. It plays an essential role in protecting the land from erosion and should not be stepped on. The Park Only Gets About 8-10 inches of Rain Every Year The Great Basin spadefoot toad has adapted to live in dry desert conditions. Kevin Schafer / Getty Images Because of the incredibly small amount of rain that falls here, the plants and animals that live at Arches have to be adapted to tough conditions. For example, the Great Basin spadefoot toad spends most of its life buried beneath the soil to avoid losing precious water through its skin. It only comes out after rains to mate and lay eggs. Burrowing owls use old burrows abandoned by prairie dogs or other animals to build their nests and raise their young out of the unforgiving heat of the high desert sun. Temperatures at Arches Can Fluctuate Over 40 Degrees in a Single Day As part of the Colorado Plateau, Arches is located in the high desert. Here, temperatures can range from 0 F to over 100 F depending on the season. While the rainfall average is very low, the rains that do come to the park tend to arrive as rainstorms that often cause flash flooding. The extreme day to night temperature fluctuations cause the water that seeps into the rocks to expand when it freezes and contracts when it thaws. This weathering is one of the erosive forces that shape the unique structures in the park. There Are 754 Known Species of Plants and Animals The biological diversity of plants and animals that call the park home puts to rest the myth that a desert is a barren place. Along with 483 plant species, including the rare canyonlands biscuitroot, the animals represent mammals, amphibians, reptiles, birds, and even fish. Four out of six of the fish species found in Arches are endangered. There Are Hidden Messages Painted on the Rocks Infrared photography revealed hidden features of the petroglyphs. andyKRAKOVSKI / Getty Images Pictographs left behind by ancient inhabitants of the land are one of the unique features of the park. These prehistoric rock markings can be found at the Courthouse Wash in Arches. A volunteer photographer took infrared pictures of the rock markings in 2007, revealing previously invisible images that helped tell more of the story of the pictographs. Balanced Rock Weighs as Much as 27 Blue Whales Balanced rock is one of the impressive non-arch geologic features in the park. Brad McGinley Photography / Getty Images This massive desert rock weighs in at an estimated 3,577 tons and stands at 128 feet tall. That’s about the length of three yellow school buses. Made of two different types of sandstone, the boulder was formed when the Dewey Bridge mudstone on the bottom eroded beneath the slick rock Entrada Sandstone on top. The attachment of the two types of rock make it appear to literally hang in the balance. Landscape Arch Is the Fifth Longest Arch in the World Landscape arch used to be thicker before a slab fell off in the 1990s. David Clayton / 500px / Getty Images The longest spanning arch in the park measures a staggering 306 feet. It’s the longest arch in North America and the fifth-longest in the world. A huge slab of rock fell from Landscape Arch in 1991, but the arch remains intact for now. View Article Sources "Arches National Park Quick Facts." National Park Service. "Arches National Park: Geologic Formations." National Park Service. "Arches National Park: Arches." National Park Service. "Biological Soil Crust of Southeast Utah." National Park Service. "Arches National Park: Weather." National Park Service. "Arches National Park: Balanced Rock." National Park Service. "Arches' Rock Stars." National Park Service. "The 1991 Landscape Arch Rock Fall." National Park Service.