| Geology |
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The Canary Islands are entirely of volcanic origin. To the north lies Madeira and to the south the Cape Verde Islands which are related to the Canary Islands as they all of volcanic origin and rise from the seabottom at a depth more than 3000 meters below the surface of the sea. Tha Canary Islands are up to twenty million years old. The oldest islands in the east are Lanzarote and Fuerteventure, and the youngest in the west are Plama and Hierro, where the volcanic activity started place only one or two million years ago. The volcanic activity rises from a “hot spot”, located under the earth’s crust. The crust with the African continent and the seabottom moves very slowly – a few cm pr year - across this hot spot and creates a track of volcanic islands. The oldest parts of Tenerife is said to be about 7 million years old. It is the steep and torn mountains in the west, the Teno peninsula and the Anaga peninsula in the east and also the striking rock formations north of Los Christianos on the southern part of the island. At that time Tenerife was hardly one island but more likely three seperate and smaller islands. The volcanic activity has continued ever since, and countless volcanic eruptions have gradually created Tenerife as we know it today. Tenerife is still considered an activ volcano, even though there is no visible activity at the moment. The last 500 years the volcano has erupted once every hundredth year.
A map showing the
eruptions  The
known eruptions all have left new craters and floods of lava, but
especially on the southern part of the island and in the area west of
Teide several small volcanos are to be found. They are signs of
frequent returning activity. Each of the cones have presumably
erupted only once. The
dominating volcanos Pico del Teide and Pico Viejo are formed within
the last 150.000 years inside Las Cañadas which are leftovers from
older volcanos. The volcanic layers, that are visible everywhere on
the island and especially where roads cut through the surroundings,
are witnesses of intense happenings. The layers alternate between
dark and hard basalt lava floods characterized by a coke-coloured
surface, and the lighter layers containing more or less fine-grained
and porous volcanic ashes, that have been hurled from the eruption
areas. In these layers you often find big and dark pieces of basalt,
which have also been hurled around during eruptions.  The
surface of Tenerife is irregular as it consists of mountains placed
mostly in higher grounds. Lowland is almost only found in the south.
The impressive construction of the island based on one eruption after
another during seven million years, is visible almost everywhere.
Only the peninsulas Anaga and Teno are lacking the remains of cones
and lava floods. In the middle of Tenerife you find the impressive
area Las Canadas. The area covers about 150 square kilometres in a
height of more than 2000 metres surrounded by an edge of mountains,
and with Teide dominating the middle. The top of the volcano is about
3718 metres above the surface of the sea.  Las
Canadas is not a crater, it is a caldera. It’s the remains of one
or several volcanoes colapsed during eruptions of lava, ashes, steam
and gasses from the craters in the deep. The remains of the old
volcanoes are now left behind as a string of mountains west, south
and east of Teide, which has grown in the middle in the caldera. To
the north the caldera edge has disappeared, perhaps covered by Teide
or perhaps has ended up in an enormous landslide into the sea to the
north. We know of eleven eruptions, but Tenerife’s volcanic
activity isn’t over. The last eruptions happend under the sea south
of the western island El Hierro late 2011 and early 2012. Everywhere on Tenerife you come across other striking landscape formations like steep valleys or rather gorges – barrancos. These
significant valleys cut their way into the landscape and have been
shaped during a great period of time. Their creation is still being
argued. The little rain falling on Tenerife can’t be the only cause
of these steep gorges. One of the most wellknown is Barranco del
Inferno located at Adeje north of Playa de las Americas.
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© Copyright Jens Ove Nielsen & Helge Hougaard