Despite the ongoing pandemic and the volcanic eruption on La Palma, we were able to once again run our trip to the Canary Islands in January 2022. Our tour took in three islands (Tenerife, La Gomera & La Palma) and offered the opportunity to explore the fascinating geology of these volcanic islands.
GeoWorld Travel’s ‘Canary Islands: Volcanic Island Hopping’ route map
Day one: Arrival day
Our tour group convened on the island of Tenerife today, giving people a chance to meet each other in person and to settle in to our accommodation on Tenerife. This year, our group comprised of guests from the UK and the Netherlands. We met in the evening for our first meal together and to chat about the plans for the coming days.
Day two: Lava tubes and the ancestral volcanoes of Tenerife
Today was the first full touring day of our tour and we spent the whole day on the island of Tenerife Our first stop was the Cueva del Viento lava tubes. Outside of Hawaii these are the longest in the world and occur in 27,000-year-old basalt that erupted from Pico Viejo, a parasitic cone of Teide volcano. The first few photos below were taken inside the lava tubes on our guided tour. We then visited the nearby Dragon Tree in Icod de Los Vinos before heading to Garachico (TF1.6). Here we saw how a 1706 lava flow blocked the port which was, at that time, the capital of Tenerife and a major port linking Spain to the Americas. In the photos below, you can see lava from 1706 in front of a fort which marked the entrance to the port and you can also see the former port, which is now a park a few hundred metres from the shore. We then moved on to Los Gigantes (TF1.2). These 600m high cliffs are made from 5 million-year-old lava that formed in the Teno volcano, an ancestral volcano of Tenerife. We also observed olivine and pyroxene crystals in the Teno basalt (pictured below). Finally, pictured in the last photo, we saw the oldest rocks in Tenerife (TF 1.1) which formed in the “central volcano” 8-12 million years ago. It is on top of this that later volcanoes grew to form the modern island of Tenerife.
Please click on images to enlarge and to read the captions Day three: Teide National Park and World Heritage Site, Tenerife
Today was spent in Teide National Park & World Heritage Site on Tenerife. This site was inscribed for Teide’s exceptional volcanology which has both basaltic and evolved magmas in an intraplate setting. The summit of Mt Teide was snow-covered when we visited, as shown in the photo below – the summit is obscured by cloud and there are dykes in the foreground. Teide is 3,715m high and was once believed to be the highest mountain on Earth. Our first stop in the national park was the Chinyero lava field (TF 3.6), where we were able to see the youngest rocks in Tenerife; the eruption here was in 1909. Further up the rift from here we saw a rare case of two very different magmas that possibly emitted in the same eruption; basanite (mafic) at the top and phonolite (evolved) at the bottom (TF 3.5). Both lava types were produced from the same eruption which interrupted their mixing and this would eventually have produced an intermediate lava. 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 (TF 3.3) and cone sheets that were intruded as the original Las Cañadas volcano inflated and contracted. We also saw phonolite obsidian flows (TF 3.10) 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). Examples of the phonolite obsidian are pictured below. Also in the Las Cañadas caldera are the Roques de Garcia (pictured below; TF 3.8) which are rock formations made up of tuff layers, landslide debris and a sill. We also saw evidence of fault-controlled hydrothermal alteration at Los Azuljios (TF 3.7) where the green mineral epidote is visible. Finally, we stopped to see giant phonolite lava balls, which formed like snowballs as they rolled down a lava flow (TF 3.2).
Please click on images to enlarge and to read the captions
Day four: South Tenerife & La Gomera
We started today on Tenerife and finished it on La Gomera. We began with a visit to Mna Amarilla, Tenerife (TF 2.4). The photo below shows our group there – they are walking on fossilised beach dunes with yellow palagonite tuff cliffs behind. The palagonite was formed when a volcanic eruption began under the sea and the ash was hydrated. As the eruption continued it became subaerial and built the Amarilla tuff cone. The next picture shows the fossilised beach dunes on the palagonite; the sea level has since fallen or the volcano has uplifted since they were deposited. Also pictured is pumice entrained in the beach sands, which possibly came from the the Caldera Rey eruption. The interior of the Amarilla tuff cone formed from Strombolian eruptions once the eruption became subaerial. We then moved on to view a channel filled with pyroclastic flow material from a trachyte eruption of Mna Guaza 926,000 years ago (TF 2.3) – the group is pictured below standing in front of this. After this, we saw the Adeje ignimbrite (TF 2.1) and the photo below shows Andrew pointing at a contact between two different pyroclastic flows which erupted around 1.5 million years ago. Next on the day’s itinerary was Caldera del Rey (TF 2.2), a rare example of a felsic phreatomagmatic eruption, which began with a trachyphonolitic intrusion encountered water leading to an intense and sustained eruption with pumice fall and pyroclastic flows. After this, we headed to the ferry port to catch our ferry for La Gomera and after a 50-minute crossing, we arrived in San Sebastian de la Gomera (pictured below – photo taken from LG2.8, with our ferry visible in the port). La Gomera is actually a younger island that Tenerife, but there have been no eruptions for the last 2ma so it is possible to see the eroded inners of the volcano. We took in some sites on La Gomera in the afternoon before heading to our hotel. We looked at a huge dyke which would have fed fissure eruptions on La Gomera (LG 2.5) – James is pictured showing how wide the feature is. We then examined chilled margins in a dyke that cuts through red scoria that had been baked by lava that flowed over it (LG 2.7). We arrived at our hotel in La Gomera, the luxurious Parador de La Gomera.
Please click on images to enlarge and to read the captions Day five: Los Organos and La Gomera
We spent the whole day on La Gomera examining its geology and the eroded remains of its volcanism. We started at the Roque de Agando (LG2.4) & (LG2.3), a trachyte dome intrusion that has been revealed by erosion. The rock is 100m high on one side & 200m high on the other. It’s summit was once a worship and burial site for the indigenous inhabitants. The second picture is another trachyte dome (and another archaeological site) called La Fortaleza (LG2.2). The trachyte spread out below the surface without erupting and was later revealed by erosion. The following pictures show yet another trachyte dome, but this has been partly eroded away revealing incredible columnar cooling joints. The site is called Los Organos (The Organ Pipes) and was reached on a boat trip. On the boat trip, we passed a village perched on the coast next to several spectacular dykes, pictured below. We then went to the Laurel Forest in Garajonay National Park & UNESCO World Heritage Site. These forests are relict ecosystems, living remnants of the old rainforests and warm temperate forests that occupied much of Europe and North Africa during the Tertiary. We then saw several dykes (LG 1.4) that are actually cone sheets radiating out of the magma chamber of a Miocene volcano that has since eroded away. The penultimate photo shows James pointing to six different generations of dykes that cross each other (LG 1.6). These dykes were emplaced beneath the Miocene volcano. One of the final sites of the day was the Roque Cano (LG 1.5) a Pliocene aged trachyte intrusion. After a full day on La Gomera, we returned to our hotel.
Please click on images to enlarge and to read the captions Day six: La Palma
We started the day with a ferry crossing from La Gomera to La Palma. Once we arrived in La Palma, we ascended to the island’s highest point, Roque de los Muchachos (2,423m) (LP2.3), to view the telescopes (pictured below) and then descended to inspect the island’s most recent eruption which was only declared over on Christmas Day 2021. From Roque de los Muchachos we had views down into the Taburiente caldera, as well as of the Bejenado and Cumbre Vieja volcanoes (or we would have done if it had not been so cloudy!) The photos below include some evidence of the destruction wreaked by the volcanic eruption – there is a house partially consumed by the lava and other parts of a town sitting amongst the lava. We were able to get a view of the new cone formed in the eruption – the yellow visible in the photo is presumably sulphur. From our vantage point, we were also able to see a new lava delta – so fresh that it was still hot and steaming! These deltas formed when the lava reached the sea, extending the coastline of the island. The final picture was from the start of the day – Mt Teide on Tenerife as seen from the ferry from La Gomera to La Palma.
Please click on images to enlarge and to read the captions Day seven: La Palma
The focus of today was geological sites in the Taburiente Caldera National Park and more of the lava flows from the last few months of eruption. It was tragic to see communities buried under the lava, and one can only imagine how terrible it must have been for the people who lost their homes. In the photos below, we can see how the lava has blocked roads and even buried a school. The initial stop was the Taburiente Caldera National Park Visitor Centre, where there is an excellent 3D model of the island and a geological display. We then visited the Barranco de las Angustias (LP1.3), where the rocks were formed by an underwater volcano or seamount and become of deeper marine origin and more metamorphosed as you progress up the barranco. We were able to see the pillow lavas, submarine volcanic breccia, dykes, gabbro and rocks that had been hydrothermally altered. James is pictured below pointing to pillow basalts; these erupted on to the sea floor as the future La Palma was a growing sea mount. We were able to see hyaloclastic glass between pillow basalts that had been hydrothermally altered (pictured) and two different generations of dykes cutting through submarine breccia (pictured). The submarine breccia formed when the seamount was emerging and the water was too shallow to form pillow basalts. We also saw gabbro, the source of the dykes and pillow basalts, which can be seen to be quite layered. One of the photos below shows our group in front of an outcrop of pillow basalts. We then made our way to the Mirador Cumbrecita , from where we were able to look into the Taburiente Caldera (LP1.2). The caldera is an erosional caldera and is where the term ‘caldera’ was first coined back 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 re-interpreted 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, Bejenado, formed on top of the debris avalanche, forming the southern wall of the caldera and helping to give it a round cauldron shape.