The La Portada Natural Monument covers an area of 31.27 hectares (77.27 acres), 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 stone, around which are arranged marine sedimentary rocks, a stratum of yellowing sandstone, and layers of the remaining fossils of shells dating back 35 to 2 million years ago.[1] 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.
Between 2003 and 2008, the monument was closed due to a landslide of an important part of its cliffs, which required remodeling of the access route and its surroundings.
Since 2010, access to the beach is prohibited to protect the flora and fauna.
La Portada is located 18 km (11 mi) north of Antofagasta, which can be accessed by Route 1 Antofagasta-Tocopilla, from which an access road diverges at kilometer 20.
^ abScheffel, Richard L.; Wernet, Susan J., eds. (1980). Natural Wonders of the World. United States of America: Reader's Digest Association, Inc. p. 301. ISBN0-89577-087-3.
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