Canary Islands 2019

People standing in front of a rock face

Canary Islands: Volcanic Island Hopping

GeoWorld Travel’s ‘Canary Islands: Volcanic Island Hopping’ route map

Day one – Tenerife to La Palma

The tour group met on Tenerife in the afternoon before taking the ferry over to La Palma for the first night. En route to the ferry there was time for a bonus stop: Amarilla Phreatomagmatic vent. This tuff cone is morphologically different to other tuff cones on Tenerife because the initial eruption was rich in seawater before evolving into a subaerial strombolian eruption. The name of the volcano Mna Amarilla means Yellow Mountain and it is yellow because of palagonite tuff which has formed due to the seawater hydrating the volcanic ash. Another great feature of the site is marine sand which was blown against the volcano cliffs when sea levels were lower. These sands are cross-bedded, contain the occasional fossil and even have pieces of pumice that would have been washed up on the fossilised beach.

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Day two – Taburiente Caldera and Barranco de las Angustias, La Palma

Today we spent our first day on La Palma, the most volcanically active of the Canary Islands. The initial stop was the Taburiente Caldera National Park Visitor Centre. Here there is an excellent 3D model of the island and a geological display. After learning about the geological history of the island, we moved on to our first stop, the Mirador de la Cumbrecita, where we were able to look down into the Taburiente Caldera. This area plays an important role in the history of geology: it was where the term caldera was first coined in 1815 by Leopold von Buch. He believed it was a “Crater of Elevation” and the lava had been precipitated on the sea floor (the theory of Neptunism). In 1854 Charles Lyell reinterpreted the caldera as an erosional caldera and later went on to debunk Neptunism showing that lava comes from volcanoes (Plutonism). However, what Charles Lyell missed is that not all the walls of the crater are the same age. The northern and western walls formed when a giant landslide removed part of the island and, soon after this, a new volcano, Bejando, formed on top of the debris avalanche, forming the southern wall of the caldera. The photos show the vertical scarp wall of the landslide, the landslide scarp wall with part of the Bejando volcano, and the group posing in front of Bejando volcano.

After lunch we moved to the base of the caldera (Barranco de las Angustias). The rocks here were formed by an underwater volcano or seamount and become of deeper marine origin and more metamorphosed as you progress up the Barranco. Initially submarine volcanic breccias are present, then these are followed by shallow water pillow lavas, followed by deep water pillows and eventually gabbro, which formed in the magma chamber of the seamount. The rocks are metamorphosed by hydrothermal processes up to greenschist facies and contain epidote and chlorite. The rocks are also cut by two different sets of dykes. The dykes that fed the seamount are now horizontal because they have been uplifted and tilted, while the dykes that fed the later subaerial volcano are vertical. The concentration of dykes increases up the Barranco and eventually makes up 100% of the rock. Some dykes also show cooling structures.

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Day three – Cumbre Vieja, La Palma

Today was all about the Cumbre Vieja volcano that forms the southern half of La Palma and is the most volcanically active area of the Canary Islands. The volcano is a rift zone and is repeatedly injected by dykes, some of which reach the surface as fissures and sometimes form cones. Our first stop was a place where lava from the 1646AD Martin eruption crosses the main road. We then moved on to the San Antonio volcano and Visitor Centre. This is one of La Palma’s most famous volcanoes. The spectacular cone has recently been shown to have formed around 3,000 years ago not in 1677AD as previously thought. This large cone would have had a very violent phreatomagmatic (with water) eruption. In 1677 there was another eruption the from two vents on the side of this cone, which covered the whole cone in scoria from this period. Once we arrived at San Antonio, we walked around the rim and, from its summit, looked down on the nearby Teneguia Volcano which formed in 1971AD, making it La Palma’s youngest on-land eruption. We then spent some time in the visitor centre before driving around Teneguia’s 1971 lava to reach the island’s most southern point, El Faro. From here we drove across a 1971 lava delta that has extended the island by 29 hectares to reach another phreatomagmatic crater, Las Indias. We then stopped to see where lava from the 1712 eruption crosses the main road before having a picnic lunch on the flows of lava from the 1585 eruption. This lava is very interesting as it consists of basanite but contain xenoliths of phonolite that were in all stages of being digested. Additionally, the eruption emitted the exotic evolved lava tephriphonolite and pushed older phonolites up into spines near the vent, producing a “crypto-dome”.

After lunch we crossed lava flows emitted in 1949 to reach a viewpoint of lava deltas created by the 1949, 1585 and 1712 eruptions. Here we marvelled at the banana plantations that now cover them thanks to imported soil. At the end of the lava delta was a magnificent lava levee in the 1712 flow. We then journeyed back up the volcano to reach our final stop at an elevation of 1300m above sea level. This was the 1949 vent, called Llano del Banco, that produced the lava flows and delta we had just seen. This eruption also has two other vents which are on the summit of Cumbre Vieja; one only degassed while the other emitted lava down the other side of the island. We will visit both of these vents tomorrow when we walk the Ruta De Los Volcanes.

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Day four – Ruta De Los Volcanes

We spent the whole day today hiking on La Palma’s Ruta de los Volcanes to reach the Duraznero and Hoyo Negro vents of the 1949 eruption. The weather was very cloudy on the way, but once we reached Duraznero and its wonderful solidified lava lake the clouds cleared for a few minutes and we were able to get some beautiful views.

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Day five- Roque De Las Muchachos

Our day today was focused on the highest place on La Palma – the Roque De Las Muchachos. From here we had amazing views down into the Taburiente caldera and of Benjando and Cumbre Vieja volcanoes. It was a great summary of our time on the island and we were able to recap all the island’s formation stories. When then had lunch in Santa Cruz de La Palma and took the afternoon ferry to Tenerife.

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Day six- lava tubes and dragon trees, Tenerife

Our first stop on Tenerife was Garachico where we saw how a lava flow in 1706AD blocked the port which was, at that time, capital of Tenerife and a major port linking Spain and the Americas. We then moved on to Icod de los Vinos where we saw the famous Dragon Tree and had lunch before visiting the nearby Cueva del Viento lava tubes. These lava tubes are the longest in the world outside Hawaii. They lie in 27,000-year-old lava that erupted from Pico Vieja (a parasitic cone of Teide). After an excellent underground tour we visited Caldera del Rey, this is a rare example of a felsic phreatomagmatic eruption. It began with a trachyphonolitic intrusion that caused small phreatic explosions when it encountered water. This was followed by an intense and sustained eruption with pumice fallout. The eruption ended with a dry eruption that produced pyroclastic flows. From this site we also had great views of Montana de Guaza. This is a trachyte tuff cone which formed 926,000 years ago and produced a 100m-thick coulee flow. We then travelled down to the port of Los Cristainos, which is overlooked by a cinder cone, to take the ferry to La Gomera where we spent the night.

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Day seven – Los Organos and La Gomera

Today we were on the beautiful island of La Gomera. This is an older volcanic island with no activity for the last 2 million years with much of the rock exposure being Miocene (8-10 million years ago). The island is heavily eroded, revealing columnar lava, dykes and felsic domes. Our first stop was the Roquede Agando, a trachyte dome that intruded around 5 million years ago. The rock is 220m high on the valley side and 100m high on the road side, and was an important religious site for the aboriginal peoples. Our next stop was to see La Fortaleza which is also a trachytic intrusion but with an unusual flat top, which may be due to near-surface ballooning, where the magma didn’t break the surface. This site is also important historically for the aboriginal people because they took refuge there during the Spanish Conquest. We then moved on to Valle Gran Rey where we took a boat tour to see the incredible cooling columns of Los Organos. These columns are actually trachyte rather than basalt (as cooling columns commonly are) and are situated in an eroded trachyte dome. After lunch we stopped for a view over the Valle Gran Rey and could see horizontal Pliocene basalts resting uncomformably on dipping Miocene basalts. The boat trip was followed by a visit to Garajonay National Park, which is also a World Heritage Site on account of its subtropical laurel cloud forest. After this, we stopped at a former quarry which contains beautiful red tuff that has been baked solid by an overlying lava flow, and is also cut by basaltic dykes. This tuff is used as building stone throughout the island. Our final stop was a huge dyke that was about 5m across and contained cooling structures.

Please click on images to enlarge and to read the captions

Day eight – Teide National Park and World Heritage Site, Tenerife

The last day of our Canary Islands geology tour was spent on the island of Tenerife. Our first stop was to learn about the relatively recent (200,000 – 2 million years ago) pre-Teide (Las Canadas Volcano), explosive history of the island. We saw two different pyroclastic flow deposits (ignimbrites) that were created in Plinian caldera-forming eruptions. We then moved on to a view point of Los Gigantes cliffs where we learnt about the early history of the island. These 600m high sea cliffs are Miocene in age and represent rocks from the Teno volcano. We then entered the Teide National Park and saw two cones that lie on Tenerife’s NW-SE rift. The cones are the Boca Cangrejo and Chinyero cones. Boca Cangrejo was seen erupting by Christopher Columbus en route to discover America in 1492AD. Chinyero is Tenerife’s most recent eruption (1909). Further up the rift from here we saw a lava flow from another cone, which was basanaite (mafic) at the top and phonolite (evolved) at the bottom; both lava types were produced from the same eruption which interrupted their mixing. This would eventually have produced an intermediate lava. We then entered the Las Canadas caldera but from this entrance there is no caldera wall due to a lateral landslip. In the centre of the caldera is the magnificent Teide volcano with its parasitic cone Pico Viejo. We stopped at a viewpoint of Pico Viejo and saw an intermediate lava – a tephriphonolite. This erupted in 1798 from a 1.5km long fissure in the side of the cone. The eruption is known as the Chahorra eruption. A little further on near the south eastern wall of the caldera, we saw ring dykes and cone sheets that were intruded as the original Las Canadas volcano inflated and contracted. Then we moved onto to an area where pumice used to be mined. This pumice was erupted 2,000 years ago in a sub-Plinian eruption from a phonolite dome called Mna Blanca. This dome pushed its way out of the base of Teide. At this site we also saw phonolite obsidian flows that were emitted from the summit of Teide around 600-900AD. It is possible to still see a lobe of this flow arresting on a steep slope, demonstrating how viscous it is (a Bingham fluid). Our penultimate stop was to see the Roques de Garcia. These photogenic rocks stick out due to erosion and consist of volcanic necks, dykes, sill and landslide debris sediments. They also mark a boundary between two different floor levels of the Las Cañadas caldera. We also saw evidence of fault-controlled hydrothermal alteration and stopped to see giant phonolite lava balls, which formed like snowballs.

Please click on images to enlarge and to read the captions

Day nine – departure

Our group dispersed after breakfast today, some choosing to fly straight home and others choosing to visit some of the other Canary Islands which are also of great geological interest. What a wonderful time we have had on these magnificent volcanoes that stick of the Atlantic Ocean in such dramatic fashion. Thank you to the group for good company and good geological discussions!

We will be running this tour again in January 2021 – see our website for details: https://www.geoworldtravel.com/Canary-Islands.php

We would also like to thank Feedspot for including us in their Top 200 Travel blogs list and their Top 30 Geology blogs list

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