Natural arch - Citizendia

"Natural Bridges" redirects here; for the US National Monument, see Natural Bridges National Monument. Natural Bridges National Monument is a US National Monument located in about 50 miles north west of the Four Corners boundary of southeast Utah, in

A natural arch or natural bridge is a natural formation (or landform) where a rock arch forms, with a natural passageway through underneath. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere An arch is a structure that spans a space while supporting weight (e 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. In Geography and Geology, a cliff is a significant vertical or near vertical rock exposure Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind A rock shelter is a shallow cave-like opening at the base of a bluff or Cliff. 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. Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere.

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. "

1 Coastline
2 Weather-eroded arches
3 Water eroded arches
4 Cave erosion
5 Gallery
6 See also
7 Notes
8 External links

Coastline

On coasts this can form two different types of archs depending on the geology. On discordant coastlines rock types run at 90° to the coast. A discordant coastline occurs where bands of differing rock type run Perpendicular to the Coast. Wave refraction concentrates the wave energy on the headland, and an arch forms when caves break through the headland, e. A wave is a disturbance that propagates through Space and Time, usually with transference of Energy. A cave is a natural underground void large enough for a human to enter g. , London Bridge in (Victoria, Australia). London Arch ( is a Natural arch in the Port Campbell National Park, Australia. For a topic outline on this subject see List of basic Australia topics. When these eventually collapse, they form stacks and stumps. A stack is a geological Landform consisting of a steep and often vertical column or columns of rock in the sea near a coast On concordant 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. concordant coastline occurs where the bands of differing rock types run parallel to the Coast. Shale (also called mudstone) is a fine-grained Sedimentary rock whose original constituents were Clay minerals or Muds It is characterized by Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 Good examples of this are at Durdle Door and Stair Hole near Lulworth Cove on the Dorset Jurassic Coast in south England, although these are on an area of concordant coastline. Durdle Door (sometimes spelled Durdle Dor) is a natural Limestone arch on the Jurassic Coast near Lulworth in Dorset, Lulworth Cove is a Cove near the village of West Lulworth, on the Jurassic Coast World Heritage Site in Dorset, south England Dorset ( (or archaically, Dorsetshire) is a county in South West England on the English Channel coast The Jurassic Coast is a World Heritage Site on the English Channel coast of southern England. England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland concordant coastline occurs where the bands of differing rock types run parallel to the Coast. When Stair Hole eventually collapses, it will form a cove. A cove is a circular or Oval Coastal Inlet with a narrow entrance

Weather-eroded arches

Deep cracks penetrate into a sandstone layer.
Erosion wears away exposed rock layers and enlarges the surface cracks, isolating narrow sandstone walls, or fins.
Alternating frosts and thawing cause crumbling and flaking of the porous sandstone and eventually cut through some of the fins.
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. Arches National Park is a US National park in southern Utah. It is known for preserving over 2000 natural sandstone arches, including the The State of Utah (ˈjuːtɔː or) is a western state of the United States.

Delicate Arch, Utah, USA

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. Delicate Arch is a tall freestanding Natural arch located in Arches National Park near Moab, Utah. The State of Utah (ˈjuːtɔː or) is a western state of the United States. The United States of America —commonly referred to as the 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 US National Monument located in about 50 miles north west of the Four Corners boundary of southeast Utah, in

Cave erosion

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. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 A cave is a natural underground void large enough for a human to enter A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or Cenote, is a natural depression

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[1]. London Arch ( is a Natural arch in the Port Campbell National Park, Australia.

Gallery

Natural Bridge National Historic Landmark in Virginia	Natural stone arch in Tirumala - Tirupati, India	London Arch, formerly "London Bridge" in Victoria, Australia	Pont d'Arc arch, S France. Natural Bridge in Rockbridge County Virginia is a geological formation in which Cedar Creek (a small Tributary of the James River) The Commonwealth of Virginia ( is an American state Tirupati ( Telugu: తిరుపతి is the richest pilgrimage city (of any religious faith in the world located in the state of Andhra Pradesh in India India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country London Arch ( is a Natural arch in the Port Campbell National Park, Australia. For a topic outline on this subject see List of basic Australia topics. The Pont d'Arc ( French pont = bridge is a great natural bridge, located in the Ardèche département in the south of
Durdle Door, Dorset coast, United Kingdom	Rainbow Bridge was formed by a meandering watercourse. Durdle Door (sometimes spelled Durdle Dor) is a natural Limestone arch on the Jurassic Coast near Lulworth in Dorset, Dorset ( (or archaically, Dorsetshire) is a county in South West England on the English Channel coast Rainbow Bridge National Monument is administered by Glen Canyon National Recreation Area, southern Utah, USA. Utah (Navajo Nation), USA	Delicate Arch, Utah, USA	Arch in Timna Park, Negev Desert, Israel. The Navajo Nation ( Diné in the Navajo language) is a semi- autonomous Native American homeland covering about 26000 square miles (67339 square Delicate Arch is a tall freestanding Natural arch located in Arches National Park near Moab, Utah. The State of Utah (ˈjuːtɔː or) is a western state of the United States. The United States of America —commonly referred to as the Timna ( Arabic, تمنة) is an ancient city in Yemen, the capital of the Qataban kingdom it is distinct from a city in Southern Israel The Negev (נֶגֶב Tiberian vocalization: Néḡeḇ) is the Desert region of southern Israel. For a topic outline on this subject see List of basic Israel topics.
Rainbow Cave arch in the Galilee, Israel. "Galil" redirects here For the weapon see IMI Galil. Galilee (הגליל ha-Galil, lit the province, For a topic outline on this subject see List of basic Israel topics.	Natural Arch (sandstone) in Daniel Boone National Forest in Kentucky. Sandstone is a Sedimentary rock composed mainly of Sand -size Mineral or rock grains. Daniel Boone National Forest is the only National forest completely within the boundary of Kentucky. The Commonwealth of Kentucky ( is a state located in the East Central United States of America.