By its wondrous size, to say nothing of its majesty and mystery, Rainbow Bridge has inspired human beings throughout time. Native Americans living in the region have long held the bridge sacred. From the time the bridge became known to the outside world in the 20 th century, thousands of people from around the world have visited each year. From its base to the top of the arch it is 290 feet – nearly the height of the Statue of Liberty – and spans 275 feet across the river; the top of the arch is 42 feet thick and 33 feet wide.
How was Rainbow Bridge formed? In a word, water. The same forces that shaped Rainbow Bridge also shaped the sandstone arches and alcoves seen elsewhere on the Colorado Plateau. Water in contact with sandstone dissolves the calcium carbonate (limestone) that cements together the sand grains. Water freezing and expanding in cracks also helps in weathering by breaking of large chucks of rock. Over millions of years a vast world of varied sculptures was created.
The rock layer from which Rainbow Bridge was formed is the relatively soft sandstone of the Navajo formation, which rests on thin layers of harder sandstone and shale which makes up the Kayenta formation. Iron oxide and manganese have colored all of this rock into varied shades of red, pink, and brown. Initially, water flowing off nearby Navajo Mountain meandered across the Navajo sandstone, following the path of least resistance on its way to the Colorado River. Over time, the channel scoured from the rock became even deeper. At the site of Rainbow Bridge, the stream happened to flow in a tight curve around a narrow fin of soft Navajo sandstone. When the stream cut down as far as the Kayenta layer, water began to force its way through the soft Navajo sandstone fin. Eventually, the stream cut completely through the fin and the beginning of Rainbow Bridge was created. Other forces – calcium carbonate dissolving and ice wedging away chunks of rock – shaped Rainbow Bridge into a nearly perfect parabola. Over time, the same forces that shaped Rainbow Bridge will dismantle it. All around the Colorado Plateau the same story is being played out in other sunset-colored canyons.
The General park map handed out at the visitor center is available on the park's map webpage.For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.
A geology photo album for this park can be found here.For information on other photo collections featuring National Park geology, please see the Image Sources page.
Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.
Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
9" x 10.75", paperback, 550 pages, full color throughout
The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!
Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.
For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.
The NPS maintains a searchable data base of research needs that have been identified by parks.
A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.
NPS Geology and Soils PartnersAssociation of American State Geologists
Geological Society of America
Natural Resource Conservation Service - Soils
U.S. Geological Survey
Currently, we do not have a listing for any park-specific geology education programs or activities.For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.