The Caldeira Volcano (

Portuguese Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Portu ...

: ) is the highest mountain, massive

stratovolcano A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...

and the largest geomorphological structure that forms the island of Faial. The mountain's highest point,

Cabeço Gordo Cabeço Gordo (Portuguese for "fat mound") is the highest point in the island of Faial, measuring above sea level. Located on the southern rim of the Caldeira Volcano, on a clear day, most of the islands of the central group of the Azores are v ...

, reaches above sea level. One of the most notable features of this volcano is its two kilometer wide

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

, that is in depth below the crater rim.

History

Along the western edge of the Ribeirinha Volcano, the Central Volcanic Complex formed about 410,000 years ago, along with several structures that arose from tectonics. Evidence of this process has not been preserved due to subsistence, but it is generally believed that two formations (an Upper and Lower group) reflecting a geochemical variation that occurred about 16,000 years ago. The Lower group (from 410,000 years ago), was marked by the predominance of a Hawaiian/Strombolian eruptive process, that was composed of basaltic and benmoreitic rocks. The secondary, Upper group, was a highly explosive period (sub-Plinian in character), which produced a series of twelve deposits of pumice and surge deposits (pyroclastic flows of trachytic and benmoreitic). The volcano was reduced by around in height due to an eruption that occurred around 1000 years ago. This was one of the last major explosive events recorded in the Azores. Although the central volcano has not been active within the past two centuries, it has seen activity related to the eruption of

Capelinhos The Capelinhos (from Capelo + ''-inhos'' diminutive, which literally means "little cape") is a monogenetic volcano located on the western coast of Faial Island in the Azores. It is part of the larger volcanic complex of Capelo, which includes 20 sc ...

(1957–58). During this period, fumaroles in the caldera became active, and the minor lakes/swamps were dried-up by excessive heat. The volcano, due to its central nature, is part of each parish on the island (except for Matriz, Conceição and Angustias).

Geography

The Caldeira Volcano is the main geomorphological unit, corresponding to a polygenetic volcano two kilometers at the top and one kilometer at the base. The walls of the crater rim are abrupt, although their slopes increase with altitudes. The superficial cover of the volcano is covered in pyroclastic material, such as pumice rock, phreatic and phreatomagmatic deposits, evidence of pyroclastic flows and lahars. The flanks of the stratovolcano also include the Morro de Castelo Branco and peninsula of denser material that have resisted erosion.

References

;Notes ;Sources * * * *{{cite journal, url=http://e-terra.geopor.pt/artigos/cong_geoq/machado.pdf, last=Machado, first=Adriane, author2=Azevedo, José M. M., author3=Alemeida, Delia P.M., author4=Farid Chemale Jr., title=Geochemistry of Volcanic Rocks from Faial Island (Azores), publisher=e-Terra, GEOTIC – Sociedade Geológica de Portugal, location=Lisbon, volume=5, 1, year=2008, pages=1–14, access-date=2010-08-22, archive-url=https://web.archive.org/web/20110511135248/http://e-terra.geopor.pt/artigos/cong_geoq/machado.pdf, archive-date=2011-05-11, url-status=dead Stratovolcanoes of Portugal Calderas of Portugal Geology of the Azores Faial Island