Rainbow Bridge was formed by a meandering watercourse. Utah (Navajo Nation), USA

A natural arch or natural bridge is a natural formation (or landform) where a rock arch forms, with a natural passageway through underneath. Most natural arches form as a narrow ridge, walled by cliffs, become narrower from erosion, with a softer rock stratum under the cliff-forming stratum gradually eroding out until the rock shelters thus formed meet underneath the ridge, thus forming the arch. Natural arches commonly form where cliffs are subject to erosion from the sea, rivers or weathering (sub-aerial processes); the processes "find" weaknesses in rocks and work on them, making them bigger until they break through. I took this pic of Rainbow Bridge in May 2002 while on vacation at Lake Powell. ... I took this pic of Rainbow Bridge in May 2002 while on vacation at Lake Powell. ... Insert non-formatted text Rainbow Bridge Rainbow Bridge in Glen Canyon National Recreation Area, southern Utah, USA, is the often described as the worlds largest natural bridge. ... Navajo sandpainting The Navajo Nation (Dineé in Navajo language) is a Native American sovereignty. ... A landform comprises a geomorphological unit. ... The rocky side of a mountain creek near Orosí, Costa Rica. ... Isometric view of a typical arch An arch is a curved structure capable of spanning a space while supporting significant weight (e. ... The Trango Towers in Pakistan have the highest cliffs in the world In geography, a cliff is a significant vertical, or near vertical, rock exposure. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as understood by materials science, see Erosion (materials science) For erosion as an English analogy, see Erosion (figurative) Erosion is the displacement of solids (soil, mud, rock and other particles) by the agents of wind, water... A rock shelter is a shallow cave-like opening at the base of a bluff or cliff. ... Weathering is the process of breaking down of rocks, soils and their minerals through direct, or indirect contact with the atmosphere. ... Sub-aerial processes refer to processes taking place above ground level, with effects on objects on the ground. ...

The choice of "bridge" vs "arch" is somewhat arbitrary. The Natural Arch and Bridge Society identifies a bridge as a subtype of arch that is primarily water-formed.^[1] By contrast, the Dictionary of Geological Terms^[2] defines a natural bridge as a "natural arch that spans a valley of erosion."

Durdle Door, Dorset coast, United Kingdom

Durdle Door. ... Durdle Door. ... Durdle Door Durdle Door (sometimes spelt Durdle Dor) is a natural limestone arch on the Jurassic Coast near West Lulworth in Dorset, England. ... Dorset (pronounced DOR-sit or [dɔ.sət], and sometimes in the past called Dorsetshire) is a county in the south-west of England, on the English Channel coast. ...

Coastline arches

On coasts this can form two different types of arch depending on the geology. On discordant coastlines or Atlantic Coastlines, rock types run at 90° to the coast, headlands form. Wave refraction concentrates the wave energy on the headland, and the arch forms when caves break through the headland, e.g., London Bridge in Victoria, Australia. When these eventually collapse they form stacks and stumps. On concordant coastlines or Pacific coastlines, rock types run parallel to the coastline, with weak rock (such as shale) protected by stronger rock (such as limestone) the wave action breaks through the strong rock and then erodes the weak rock very quickly. Good examples of this are at Durdle Door (illustration, above) and Stair Hole near Lulworth Cove on the Dorset Jurassic Coast in south England, although these are on an area of concordant coastline. When Stair hole eventually collapses it will form a cove. It has been suggested that this article or section be merged with Concordant coastline. ... The bay at San Sebastián, Spain A headland is an area of land adjacent to water on three sides. ... It has been suggested that this article be split into articles entitled wave, accessible from a disambiguation page. ... Lechuguilla Cave, New Mexico This article is about natural caves; for artificial caves used as dwellings, such as those in north China, see yaodong. ... London Arch London Arch is a natural arch in the Port Campbell National Park, Australia. ... Capital Melbourne Government Const. ... Big Flowerpot, Canada Old Man of Hoy, Scotland Stack near Old Harry Rocks, England A stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast. ... A stump is the remains of an object that has been cut or broken, for example, when a tree has been felled. ... A concordant coastline is a coastline where bands of different rock types run parallel to the shore. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Limey shale overlaid by limestone. ... Durdle Door Durdle Door (sometimes spelt Durdle Dor) is a natural limestone arch on the Jurassic Coast near West Lulworth in Dorset, England. ... Lulworth Cove Lulworth Cove is a cove near the village of West Lulworth, on the Jurassic Coast World Heritage Site in Dorset, south England. ... Dorset (pronounced DOR-sit or [dÉ”.sÉ™t], and sometimes in the past called Dorsetshire) is a county in the south-west of England, on the English Channel coast. ... Lyme Bay. ... Motto: (French for God and my right) Anthem: God Save the King/Queen Capital London (de facto) Largest city London Official language(s) English (de facto) Unification    - by Athelstan AD 927  Area    - Total 130,395 km² (1st in UK)   50,346 sq mi  Population    - 2006 est. ... A concordant coastline is a coastline where bands of different rock types run parallel to the shore. ... Insert non-formatted text here Lulworth Cove, Dorset England This article is about the coastal feature. ...

Weather-eroded arches

1. Deep cracks penetrate into a sandstone layer.
2. Erosion wears away exposed rock layers and enlarges the surface cracks, isolating narrow sandstone walls, or fins.
3. Alternating frosts and thawing cause crumbling and flaking of the porous sandstone and eventually cut through some of the fins.
4. The resulting holes become enlarged to arch proportions by rockfalls and weathering. Arches eventually collapse, leaving only buttresses that in time will erode.

Many of these arches are found within Arches National Park in Utah. arch formation from NPS website This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... Arches National Park preserves over 2,000 natural sandstone arches, including the world-famous Delicate Arch, in addition to a variety of unique geological resources and formations. ... To meet Wikipedias quality standards, the lead section of this article may need to be expanded. ...

Delicate Arch, Utah, USA

ImageMetadata File history File links Download high resolution version (3072x1812, 1418 KB) Summary Delicate Arch, located at Arches National Park in Moab, Utah. ... ImageMetadata File history File links Download high resolution version (3072x1812, 1418 KB) Summary Delicate Arch, located at Arches National Park in Moab, Utah. ... Delicate Arch Delicate Arch Delicate Arch from the rear Delicate Arch grooves caused by Dean Potter Delicate Arch is a freestanding natural arch located in Arches National Park near Moab, Utah. ... To meet Wikipedias quality standards, the lead section of this article may need to be expanded. ...

Water eroded arches

Some natural bridges may look like arches, but they form in the path of streams that wear away and penetrate the rock. Pothole arches form by chemical weathering as water collects in natural depressions and eventually cuts through to the layer below.

Natural Bridges National Monument is a superb place to view these bridges. Natural Bridges National Monument is a U.S. National Monument located in the southeast of Utah, in the western United States. ...

Cave erosion

London Arch, formerly "London Bridge" in Victoria, Australia

Natural bridges can form from natural limestone caves, where paired sinkholes collapse and a ridge of stone is left standing in between, with the cave passageway connecting from sinkhole to sinkhole. Image File history File links Picture of London Arch, Victoria, circa 1993. ... Image File history File links Picture of London Arch, Victoria, circa 1993. ... London Arch London Arch is a natural arch in the Port Campbell National Park, Australia. ... Capital Melbourne Government Const. ... Limey shale overlaid by limestone. ... Lechuguilla Cave, New Mexico This article is about natural caves; for artificial caves used as dwellings, such as those in north China, see yaodong. ... Devils Hole near Hawthorne, Florida Sinkholes, also known as sinks, shakeholes or dolina (in the Slovene language dolina means valleys), and cenotes, are formed by the collapse of cave roofs and are a feature of landscapes that are based on limestone bedrock. ...

Like all rock formations, natural bridges are subject to continued erosion, and will eventually collapse and disappear. One example of this was the double-arched Victorian coastal rock formation, London Bridge which lost an arch after storms increased erosion. London Bridge before it collapsed Capital Melbourne Government Const. ... London Arch London Arch is a natural arch in the Port Campbell National Park, Australia. ...

Natural stone arch in Tirumala - Tirupati, India

Image File history File links Tirumala_natural_stone_arch. ... Image File history File links Tirumala_natural_stone_arch. ... This article is about the town of Tirumala-Tirupati in Andrapradesh, India. ...

See also

• Bridge
• Ayres Natural Bridge State Park (Wyoming)
• Creelsboro Natural Bridge (Kentucky)
• Étretat (France)
• Grosvenor Arch (Utah)
• Kolob Arch
• Llanrhaeadr-ym-Mochnant (Wales)
• Natural Bridge Caverns, Texas
• Natural Bridge State Park (Kentucky)
• Natural Bridge State Park (Massachusetts)
• Natural Bridge, Virginia
• Natural Bridges State Beach (California)
• Parque Nacional de Sete Cidades (Brazil)
• Percé Rock
• Pont d'Arc
• Pravcicka Brana (Czech Republic)
• Rattlesnake Canyon (Colorado)
• Sewanee Natural Bridge
• Tassili n'Ajjer
• El Arco de Cabo San Lucas (Mexico)
• Punarjani Guha - natural tunnel

A log bridge in the French Alps near Vallorcine. ... Ayres Natural Bridge Ayres Natural Bridge State Park is a state park of Wyoming in the United States. ... Official language(s) English Capital Cheyenne Largest city Cheyenne Area  Ranked 10th  - Total 97,818 sq mi (253,348 km²)  - Width 280 miles (450 km)  - Length 360 miles (580 km)  - % water 0. ... Photo credit: Jay Wilbur Creelsboro Natural Bridge (more commonly referred to as Rock House or Rockhouse) is a natural bridge in Eastern Russell County, Kentucky, USA. It is located near the town of Creelsboro, approximately seven miles from the Wolf Creek Dam and Lake Cumberland. ... Official language(s) English[1] Capital Frankfort Largest city Louisville Area  Ranked 37th  - Total 40,444 sq mi (104,749 km²)  - Width 140 miles (225 km)  - Length 379 miles (610 km)  - % water 1. ... Cliff and natural arch in Étretat Étretat is a commune of the Seine-Maritime département in France. ... Grosvenor Arch is a unique sandstone double arch located in southern Utah. ... To meet Wikipedias quality standards, the lead section of this article may need to be expanded. ... Categories: Stub | Natural arches ... Llanrhaeadr-ym-Mochnant is a village in Powys, Wales, lying on the River Rhaeadr by the Berwyn Mountains. ... This article is about the country. ... Natural Bridge Caverns are the largest known caverns in the state of Texas. ... Official language(s) English (de facto) See also languages of Texas Capital Austin Largest city Houston Area  Ranked 2nd  - Total 268,581 sq mi (695,622 km²)  - Width 773 miles (1,244 km)  - Length 790 miles (1,270 km)  - % water 2. ... Looking up at the natural bridge Natural Bridge State Park is a Kentucky state park located in Powell County, Kentucky along the Middle Fork of the Red River, adjacent to the Red River Gorge Geologic Area and surrounded by the Daniel Boone National Forest. ... Official language(s) English[1] Capital Frankfort Largest city Louisville Area  Ranked 37th  - Total 40,444 sq mi (104,749 km²)  - Width 140 miles (225 km)  - Length 379 miles (610 km)  - % water 1. ... Natural Bridge State Park is a Massachusetts state park located in North Adams, in the northwestern part of the state. ... This article is about the U.S. State. ... Natural Bridge in Rockbridge County, Virginia circa 1909 Natural Bridge in Rockbridge County, Virginia is a geological formation in which Cedar Creek has carved out a gorge of the limestone mountainous terrain, forming an arch 215 ft (66 m) high with a span of 90 ft (27 m). ... Natural Bridges State Beach is a protected area in Santa Cruz, California, featuring a natural bridge across a section of the beach. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... Percé Rock Percé Rock (French rocher Percé, pierced rock) is one of the largest and most spectacular natural arches in the world. ... The Pont dArc (French pont = bridge) is a great natural bridge, located in the Ardèche département in the south of France, near the town of Vallon-Pont-dArc. ... The arches loop trail starts with a tricky descent through Cedar Tree Arch. ... Official language(s) English Capital Denver Largest city Denver Area  Ranked 8th  - Total 104,185 sq mi (269,837 km²)  - Width 280 miles (451 km)  - Length 380 miles (612 km)  - % water 0. ... Sewanee Natural Bridge Sewanee Natural Bridge in Franklin County, Tennessee, is a 25 feet (8 m) high natural sandstone arch with a span of 50 feet (15 m). ... Landsat image of the Tassili nAjjer The Tassili nAjjer (Arabic: تصلة ناجر) is a mountain range in the Sahara desert in southeast Algeria. ... The distinctive El Arco rock formation El Arco de Cabo San Lucas is is a distinctive rock formation at the southern tip of Cape San Lucas, which is itself the extreme southern end of Mexicos Baja California Peninsula. ... Punarjani Guha is a natural tunnel 15 meters long in the rocky cliff. ...

Notes

1. ^ Natural Arch and Bridge Society, FAQ.
2. ^ American Geological Institute, Dictionary of Geological Terms, 1976, Doubleday Anchor

External links

Wikimedia Commons has media related to:

Natural arches

• The Natural Arch and Bridge Society homepage