La Portada is a natural arch

Natural arch

A natural arch or natural bridge is a natural geological formation where a rock arch forms, with an opening 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...

 on the coast of Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, 18 km (11.2 mi) north of Antofagasta

Antofagasta

Antofagasta is a port city in northern Chile, about north of Santiago. It is the capital of Antofagasta Province and Antofagasta Region. According to the 2002 census, the city has a population of 296,905...

. It is one of fifteen natural monuments included among the protected areas of Chile

Protected areas of Chile

The protected areas of Chile are areas that have natural beauty or significant historical value protected by the government of Chile. These protected areas cover over , which is 19% of the territory of Chile...

.

There is another similar but smaller structure in the spa town

Spa town

A spa town is a town situated around a mineral spa . Patrons resorted to spas to "take the waters" for their purported health benefits. The word comes from the Belgian town Spa. In continental Europe a spa was known as a ville d'eau...

 of Pucatrihue, Osorno Province

Osorno Province

Osorno Province is one of the four provinces in the southern Chilean region of Los Lagos . The province has an area of and a population of 221,509 distributed across seven communes . The provincial capital is the city of Osorno....

.

Description

The La Portada Natural Monument covers an area of 31.27 hectare

Hectare

The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

s (77.27 acre

Acre

The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...

s), and its geomorphological features and remaining fossils stand out in the form of an arch.

The arch of La Portada is 43 m (140 ft) high, 23 m (75 ft) wide, and 70 m (230 ft) long. It has a base of black andesite

Andesite

Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...

 stone, around which are arranged marine sedimentary rock

Sedimentary rock

Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

s, a stratum of yellowing sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

, and layers of the remaining fossils of shells dating back 35 to 2 million years ago. All this was formed during a long process of marine erosion.

The arch is surrounded by coastal cliffs that were also formed by marine erosion. They reach a maximum height of 52 m above sea level.

On 5 October 1990, it was declared a natural monument under Supreme Decree #51 of the Ministry of Agriculture, published in the Diario Oficial.

Since March 2003, this natural monument remains closed due to a landslide of an important part of its cliffs, which blocked access to its beach. For this reason, a remodeling of the access route and its surroundings is planned.

Fauna

The natural monument constitutes an observation site for guano

Guano

Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...

 birds such as Peruvian Booby

Peruvian Booby

The Peruvian Booby, Sula variegata, is an endemic bird of the Peruvian current whose distribution is restricted to the west coast of South America from Punta Pariñas in Peru to Concepción in Chile . It is the second most abundant seabird species that inhabits the Peruvian Coast and the second...

 (Sula variegata) and Inca Tern

Inca Tern

The Inca Tern is a seabird in the family Sternidae. It is the only member of the genus Larosterna.This uniquely-plumaged bird breeds on the coasts of Peru and Chile, and is restricted to the Humboldt current...

s (Larosterna inca), as well as Guanay Cormorant

Guanay Cormorant

The Guanay Cormorant or Guanay Shag is a member of the cormorant family found in on the Pacific coast of Peru and northern Chile...

s (Phalacrocorax bougainvillii), Kelp Gull

Kelp Gull

The Kelp Gull , also known as the Dominican Gull, breeds on coasts and islands through much of the southern hemisphere. The race L. d. vetula occurs around southern Africa, and nominate L. d...

s (Larus dominicanus), Grey Gull

Grey Gull

This article is about the bird. For the record label, see Grey Gull Records.The Grey Gull is a gull found along the Pacific coast of South America...

s (Larus modestus), Belcher's Gull

Belcher's Gull

The Belcher's Gull , also known as the or Band-tailed Gull, is a gull found along the Pacific coast of South America. It formerly included the very similar Olrog's Gull as a subspecies. It is a medium-sized gull with a blackish mantle, white head and underparts, a black band in the otherwise white...

s (Larus Belcheri), and pelican

Pelican

A pelican, derived from the Greek word πελεκυς pelekys is a large water bird with a large throat pouch, belonging to the bird family Pelecanidae....

s.

Occasionally one can also observe mammals such as the South American Fur Seal

South American Fur Seal

The South American Fur Seal is a species of fur seal that breeds on the coasts of Chile and Argentina. The total population is around 250,000....

 (Arctocephalus australis) or the Common Dolphin

Common dolphin

The common dolphin is the name given to two species of dolphin making up the genus Delphinus.Prior to the mid-1990s, most taxonomists only recognised one species in this genus, the common dolphin Delphinus delphis...

 (Delphinus delphis).

Access

La Portada is located 18 km (11.2 mi) north of Antofagasta, which can be accessed by Route 1 Antofagasta-Tocopilla, from which an access road diverges at kilometer 20.

The monument is found near the Cerro Moreno International Airport

Cerro Moreno International Airport

Cerro Moreno International Airport is an airport in Antofagasta, Chile. It is located north of Antofagasta.- Destinations :...

 and La Chimba National Reserve.

External links

Corporación Nacional Forestal. Servicio Nacional de Turismo.