Natural arch

Natural Arch

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Natural arch

"Natural Bridges" redirects here; for the US National Monument, see Natural Bridges National Monument
Natural Bridges National Monument

Natural Bridges National Monument is a U.S. National Monument located about north west of the Four Corners boundary of southeast Utah, in the western United States, at the junction of White Canyon and Armstrong Canyon, part of the Colorado River drainage....
.

A natural arch or natural bridge is a natural formation (or landform

Landform

In the earth sciences and geology sub-fields a landform or physical feature comprises a geomorphology unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography....
) where a rock

Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
arch

Arch

An arch is a structure that Span a space while supporting weight . Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture, but their systematic use started with the Ancient Rome who were the first to apply the technique to a wide range of structures....
forms, with a natural passageway through underneath.

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A natural arch or natural bridge is a natural formation (or landform

Landform

Rock (geology)

In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock....
arch

Arch

Cliff

In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them....
s, become narrower from erosion

Erosion

For morphological image processing operations, see Erosion 'For use of in dermatopathology, see Erosion Erosion is the removal of solids in the natural environment....
, with a softer rock stratum under the cliff-forming stratum gradually eroding out until the rock shelter

Rock shelter

A rock shelter is a shallow cave-like opening at the base of a bluff or cliff.Rock shelters form because a Rock stratum such as sandstone that is resistant to erosion and weathering has formed a cliff or bluff, but a softer stratum, more subject to erosion and weathering, lies just below the resistant stratum, and thus undercuts the cli...
s 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

Weathering

Weathering is the decomposition of earth Rock , soils and their minerals through direct contact with the planet's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, wind, and gravity....
(sub-aerial processes); the processes "find" weaknesses in rocks and work on them, making them bigger until they break through.

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. By contrast, the Dictionary of Geological Terms defines a natural bridge as a "natural arch that spans a valley of erosion."

Coastline

On coasts this can form two different types of arches depending on the geology. On discordant coastline

Discordant coastline

A discordant coastline occurs where bands of differing Rock type run perpendicular to the coast.The differing resistance to erosion leads to the formation of headlands and bays....
s rock types run at 90° to the coast. Wave refraction

Wave

A wave is a disturbance that propagates through space and time, usually with transference of energy. While a mechanical wave exists in a medium , waves of electromagnetic radiation can travel through vacuum, that is, without a medium....
concentrates the wave energy on the headland, and an arch forms when cave

Cave

A cave is a natural underground void large enough for a human to enter. Some people suggest that the term cave should only apply to cavities that have some part that does not receive daylight; however, in popular usage, the term includes smaller spaces like sea caves, rock shelters, and grottos....
s break through the headland, e.g., London Bridge

London Arch

London Arch is a natural arch in the Port Campbell National Park, Australia.The arch is one of the tourist attractions along the Great Ocean Road near Port Campbell in Victoria ....
in (Victoria

Victoria (Australia)

File:Map Victoria Aboriginal tribes .jpgVictoria is a States and territories of Australia located in the southeastern corner of Australia. It is the smallest mainland state in area but the most Population density and urbanised....
, Australia

Australia

Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
). When these eventually collapse, they form stacks

Stack (geology)

A stack is a Geology landform consisting of a steep and often vertical column or columns of rock in the sea near a coast. Stacks are formed when part of a headlands and bays is erosion by hydraulic action, which is the force of the sea or water crashing against the rock....
and stumps. On concordant coastline

Concordant coastline

A concordant coastline occurs where the bands of differing Rock types run parallel to the coast. The outer hard rock provides a protective barrier to erosion of the softer rocks further inland....
s rock types run parallel to the coastline, with weak rock (such as shale

Shale

Shale is a fine-grained sedimentary rock whose original constituents were clay minerals or muds. It is characterized by thin laminae breaking with an irregular curving fracture, often splintery and usually parallel to the often-indistinguishable bedding plane....
) protected by stronger rock (such as limestone

Limestone

File:Limestone Formation In Waitomo.jpgLimestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geology record....
) the wave action breaks through the strong rock and then erodes the weak rock very quickly. Good examples of this are at Durdle Door

Durdle Door

Durdle Door is a natural limestone natural arch on the Jurassic Coast near West Lulworth in Dorset, England....
and Stair Hole near Lulworth Cove

Lulworth Cove

Lulworth Cove is a cove near the village of West Lulworth, on the Jurassic Coast World Heritage Site in Dorset, southern England. The cove is one of the finest examples of such a landform in the world, and is a tourist location, with over 1 million visitors a year....
on the Dorset

Dorset

Dorset , is a Counties of England in South West England on the English Channel coast. The county town is Dorchester, Dorset, situated in the south of the county at ....
Jurassic Coast

Jurassic Coast

The Jurassic Coast is a World Heritage Site on the English Channel coast of southern England. The site stretches from Orcombe Point near Exmouth, Devon in East Devon to Old Harry Rocks near Swanage in East Dorset, a distance of ....
in south England

England

Concordant coastline

A concordant coastline occurs where the bands of differing Rock types run parallel to the coast. The outer hard rock provides a protective barrier to erosion of the softer rocks further inland....
. When Stair Hole eventually collapses, it will form a cove

Cove

A cove is a circular or oval coastal inlet with a narrow entrance. Colloquially, the term can be used to describe a sheltered headlands and bays....
.

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

Arches National Park

Arches National Park is a United States national park in eastern Utah. It is known for preserving over 2,000 natural arch, including the world-famous Delicate Arch, in addition to a variety of unique geological resources and formations....
in Utah

Utah

The State of Utah is a western United States U.S. state of the United States. It was the List of U.S. states by date of statehood admitted to the United States on January 4, 1896....
.

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

Natural Bridges National Monument

Natural Bridges National Monument is a U.S. National Monument located about north west of the Four Corners boundary of southeast Utah, in the western United States, at the junction of White Canyon and Armstrong Canyon, part of the Colorado River drainage....
and The Big South Fork is a superb place to view these bridges.

Cave erosion

Natural bridges can form from natural limestone

Limestone

Cave

Sinkhole

A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the surface topography caused by the removal of soil or bedrock, often both, by water....
s collapse and a ridge of stone is left standing in between, with the cave passageway connecting from sinkhole to sinkhole.

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 Victoria

Victoria (Australia)

London Arch

London Arch is a natural arch in the Port Campbell National Park, Australia.The arch is one of the tourist attractions along the Great Ocean Road near Port Campbell in Victoria ....
, which lost an arch after storms increased erosion.

Arches as highways

In a few places in the world, natural arches are truly natural bridges because there are roads running across them. Two such arches are found in Kentucky. One, a cave erosion arch made of limestone, is located in Carter Caves State Park, and it has a paved road on top. Another, a weather-eroded sandstone arch with a dirt road on top, is located on the edge of Natural Bridge State Resort Park. It is called White's Branch Arch (also known as the Narrows), and the road going over it is usually referred to as the Narrows Road.

Gallery

Although the islands are close to the shore of densely-populated Southern California, their isolation has left them relatively undeveloped.Channel Islands National Park is a United States national park that consists of five of the eight Channel Islands of California off the coast of the U.S....
, California

California

California is a U.S. state on the West Coast of the United States of the United States, along the Pacific Ocean. It is bordered by Oregon to the north, Nevada to the east, Arizona to the southeast, and to the south the Mexico state of Baja California....
, USA Ayres Natural Bridge State Park

Ayres Natural Bridge State Park

Ayres Natural Bridge Park is a county park of Converse County, Wyoming, Wyoming in the United States. It occupies 150 acres southeast of the town of Glenrock, Wyoming....
, Wyoming

Wyoming

The State of Wyoming is a sparsely populated U.S. state in the Northwestern United States of the United States. The majority of the state is dominated by the mountain ranges and rangelands of the Rocky Mountains, while the easternmost section of the state is a high altitude prairie region known as the High Plains ....
, USA Azure Window

Azure Window

The Azure Window is perhaps the Maltese archipelago's most spectacular natural landmark. It features a table-like rock over the sea, is one of the most photographed vistas of the Maltese Islands, and its particularly spectacular during winter when waves crash high inside the arch....
, Gozo

Gozo

Gozo is an island of the Malta#Islands in the Mediterranean Sea, the island is part of the Southern European country Malta and is the second largest after the Malta Island itself within the archipelago....
, Malta

Malta

Malta , officially the Republic of Malta , is a densely populated developed country European microstates microstate in the European Union....
El Arco de Cabo San Lucas

El Arco de Cabo San Lucas

El Arco de Cabo San Lucas or Lands End, Cabo San Lucas is a distinctive rock formation at the southern tip of Cabo San Lucas,which is itself the extreme southern end of Mexico's Baja California Peninsula....
, Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federalism constitutionalism republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of Mexico....
Bryce Canyon National Park

Bryce Canyon National Park

Bryce Canyon National Park is a national park located in southwestern Utah in the United States. Contained within the park is Bryce Canyon....
, Utah

Utah

The State of Utah is a western United States U.S. state of the United States. It was the List of U.S. states by date of statehood admitted to the United States on January 4, 1896....
, USA Castell de Castells

Castell de Castells

Castell de Castells is a small village high in the mountains of the Marina Alta on the Costa Blanca in South Eastern Spain. The village is at the source of the Rio Jalon and surrounded by some beautiful mountains....
, Spain

Spain

Spain or the Kingdom of Spain , is a country located in Southern Europe on the Iberian Peninsula.The Spanish constitution does not establish any official denomination of the country, even though Espa?a , Estado espa?ol and Naci?n espa?ola are used interchangeably....
Creelsboro Natural Bridge

Creelsboro Natural Bridge

Creelsboro Natural Bridge is a natural arch in Western Russell County, Kentucky, United States . It is located near the town of Creelsboro, approximately seven miles from the Wolf Creek Dam and Lake Cumberland....
, Kentucky

Kentucky

The Commonwealth of Kentucky is a U.S. state located in the East Central United States of America. Kentucky is normally included in the group of Southern United States , but it is uncommonly included, geographically and culturally, in the Midwestern United States....
, USA Engetsu-to, Shirahama, Wakayama

Shirahama, Wakayama

is a towns of Japan located in Nishimuro District, Wakayama, Wakayama Prefecture, Japan.As of September 1, 2007, the town has an estimated population of 23,180 and a population density of 115 persons per km?....
, Japan

Japan

Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south....
Étretat

Étretat

?tretat is a commune in France in the Seine-Maritime d?partement in France of France....
, France

France

France , officially the French Republic , is a country whose Metropolitan France is located in Western Europe and that also comprises various Overseas departments and territories of France....
Goat Rock Beach

Goat Rock Beach

Goat Rock Beach is a sand beach in northwestern Sonoma County, California, United States.This landform is a sub-unit of Sonoma Coast State Beach, owned and managed by the State of California....
, California

California

Grosvenor Arch

Grosvenor Arch is a unique sandstone double natural arch located in southern Utah. It is named to honor Gilbert Hovey Grosvenor , a president of the National Geographic Society, publishers of the National Geographic Magazine....
, Utah

Utah

Kolob Arch

Kolob Arch is a natural arch in Zion National Park, Utah.The Natural Arch and Bridge Society considers Kolob Arch to be the second longest natural arch in the world....
, Utah

Utah

Llanrhaeadr-ym-Mochnant

Llanrhaeadr-ym-Mochnant is a village in Powys, mid Wales. Population 1,470 , Welsh-speaking 62% . The village is best known as the former parish of William Morgan , then a vicar who first translated the Bible into Welsh language and later rose to become a Bishop at Llandaff Cathedral and St....
, Wales

Wales

native_name = Cymru|conventional_long_name = Wales|common_name = Wales|image_flag = Flag of Wales 2.svg|national_motto = ...
, UK Natural Bridge Caverns

Natural Bridge Caverns

Natural Bridge Caverns are the largest known commercial caverns in the state of Texas. The name was derived from the 20 m natural limestone slab bridge that spans the amphitheater setting of the cavern's entrance....
, Texas

Texas

Texas is a U.S. state located in the South Central United States, nicknamed the Lone Star State. Texas is the second largest U.S. state in both area and population, spanning , and with a growing population of 24.3 million residents....
, USA Natural Bridge State Park

Natural Bridge State Park (Kentucky)

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....
, Kentucky

Kentucky

Natural Bridge State Park (Massachusetts)

Natural Bridge State Park is a Massachusetts state park located in North Adams, in the northwestern part of the state. It contains the only natural white marble arch/bridge in North America....
, Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a U.S. state located in the New England region of the Northeastern United States United States. It borders Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north....
, USA Natural Bridge, Virginia

Natural Bridge (Virginia)

Natural Bridge in Rockbridge County, Virginia is a geological formation in which Cedar Creek has carved out a gorge in the mountainous limestone terrain, forming an arch 215 ft high with a span of 90 ft ....
, USA Natural Bridges National Monument

Natural Bridges National Monument

Utah

Natural Bridges State Beach

Natural Bridges State Beach is a protected area in Santa Cruz, California, California, featuring a natural bridge across a section of the beach....
, California

California

Brazil

Brazil , officially the Federative Republic of Brazil , is a country in South America. It is the List of countries and outlying territories by total area country by geographical area, occupying nearly half of South America, the List of countries by population country, and the fourth most populous democracy in the world....
Percé Rock

Percé Rock

Perc? Rock is an island and sheer rock formation in the Gulf of Saint Lawrence just off the tip of the Gasp? Peninsula in Quebec, Canada, near the village of Perc?, Quebec....
, Quebec

Quebec

Quebec , in French language, Qu?bec , is a Provinces and territories of Canada in the Central Canada and Eastern Canada regions of Canada....
, Canada

Canada

Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean....
Pont d'Arc

Pont d'Arc

File:Pont d'Arc arch.JPGThe Pont d'Arc is a great natural arch, located in the Ard?che departments of France in the south of France, near the town of Vallon-Pont-d'Arc....
, France

France

Czech Republic

The Czech Republic , is a landlocked country in Central Europe. The country borders Poland to the northeast, Germany to the west, Austria to the south and Slovakia to the east....
Punarjani Guha

Punarjani Guha

Punarjani Guha is a natural tunnel 150 meters long in the rocky cliff. It is in the Palakkad district of Kerala state, south India. Punarjani Guha is situated 2 km from the Thiruvilwamala Temple and the chief presiding deity is Sri Rama....
- natural tunnel, India

India

India, officially the Republic of India , is a country in South Asia. It is the List of countries and outlying territories by total area country by geographical area, the List of countries by population country, and the most populous liberal democracy in the world....
Rainbow Cave (actually an arch) in the Galilee

Galilee

Galilee , is a large region in northern Israel which overlaps with much of the administrative North District of the country. Traditionally divided into Upper Galilee , Lower Galilee , and Western Galilee , extending from Dan to the north, at the base of Mount Hermon, along Mount Lebanon to the ridges of Mount Carmel and Mount Gilboa t...
. Rattlesnake Canyon

Rattlesnake Canyon (Colorado)

Rattlesnake Canyon is a scenic area within the Black Ridge Canyons Wilderness which in turn forms the core of the Bureau of Land Management administered McInnis Canyons National Conservation Area in west central Colorado....
, Colorado

Colorado

The State of Colorado is a U.S. state located in the Mountain States of the United States of America. Colorado may also be considered to be a part of the Western United States and Southwestern United States regions of the United States....
, USA Senkanmatsu-shima, Iwami, Tottori

Iwami, Tottori

is a towns of Japan located in Iwami District, Tottori, Tottori Prefecture, Japan.As of March 1, 2008, the town has an estimated population of 12,827 and a population density of 105 persons per km?....
, Japan

Japan

Sewanee Natural Bridge

Sewanee Natural Bridge in Franklin County, Tennessee, is a 25 feet high natural Natural arch with a span of 50 feet . It is essentially a giant sinkhole partially eroded to form a large stone bridge....
, Tennessee

Tennessee

Tennessee is a U.S. state located in the Southern United States United States. In 1796, it became the sixteenth state to join the United States....
, USA Springbrook National Park

Springbrook National Park

Springbrook is a national park in Queensland, , 78 km south of Brisbane, Australia. It is part of the World Heritage site Central Eastern Rainforest Reserves....
, Queensland

Queensland

Queensland is a States and territories of Australia of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south....
, Australia

Australia

Tassili n'Ajjer

Tassili n'Ajjer is a mountain range in the Sahara desert in southeast Algeria, North Africa. It extends about 500 km from east-south-east to , and the highest point is Adrar Afao, 2158 m, at ....
- National Park in Algeria

Algeria

Algeria , officially the People's Democratic Republic of Algeria, is a country located in North Africa. It is the largest country of the Mediterranean sea, second largest in the Arab World, and the second largest on the African continent and the eleventh-largest country in the world in terms of land area....
with many arches. Tonto Natural Bridge

Tonto Natural Bridge

Tonto Natural Bridge is believed to be the largest natural travertine bridge in the world. The area surrounding the bridge has been made into an Arizona state park called Tonto Natural Bridge State Park, which is located off State Route 87 , just 10 miles north of Payson, Arizona....
, Arizona

Arizona

The State of Arizona is a U.S. state located in the Southwestern United States of the United States. The capital and largest city is Phoenix, Arizona....
, USA Tukuyu

Tukuyu

Tukuyu is a small, of 50,000 inhabitants, hillside town that lies about south of the city of Mbeya, at an elevation of around in the highland Rungwe District of southern Tanzania, East Africa....
natural bridge.

Natural arch

Coastline

Weather-eroded arches

Water eroded arches

Cave erosion

Arches as highways

Gallery

See also

External links