If volcanoes were artists, they would be impressionists. Volcanoes are dramatic. They rise elegant cones towards the sky, painting the sky red during eruptions. Bright orange rivers of floating lava give way to mighty, wild, twisted, landscapes when the show cools down. And the colours: a palette of rough black, brown, grey, red, white, yellow…
From El Teide’s tall, sturdy, slightly bulging cone, to small sediment patterns; this blog post is a meandering walk through some of the artistic impressions of the great volcano. Volcanoes spew not only lava, but also lots of ash, rich in iron and sulphur, which wither into bright colours. Lava flowing into lakes cool to form weird shapes and pillows, and the ash lies down like blankets, only to be eroded, scoured, mixed by rivers and waves.
Lets’s go again to the Canary Islands, for a trip on and around Teide, to see some of the great impressionist’s paintings. We start with some landscape pictures to show how big the mountain really is. On the digital canvas is the view from north towards south, across the valley and the town of La Laguna. Around are green farm lands, and the northern of Tenerife’s two airports. And, in the background, a now familiar cone, towering above the tiny human dwellings.
The La Laguna valley is notoriously foggy, and as the clouds descend, they make the mountain look like it flies high in the sky. Or is it an enormous flying saucer, a visitor from outer space?
Let’s go up on Teide itself. From near the top, 3718 meters above the sea, we literally look down onto the neighbor islands. La Gomera, the green pearl of the Canary Islands, looks like she floats between sea and sky. The crater Pico Viejo (Little Peak), in the front, was once a red-hot lake of lava. You can still see the solid remnants of the lava lake in the left corner of the crater, a reminder of Tenerife’s fiery past, and the magma that still glows in the deep. The last eruption on Teide was in 1789 – a blink in geological time, and draped the south flank in black lava, contrasting the weathered brown lava from older days.
Paintings do not need lots of colors to impress. The desert around Teide is a muted palette of brown, grey and yellow, and yet it has its own, strange beauty. If the planet Mars had moved into Grand Canyon, it would have looked like this: Steep walls show layers of yellow-brown ash and dark lava from nearly two million years of eruptions. The steep walls themselves are the rim of a caldera (Spanish for cauldron), formed when the magma chamber collapsed and the volcano above it sank in. Later, the peak of Teide grew up from the caldera, smaller volcanic cones sprinkle the cake.
Muggles often think of volcanoes as one big heap of lava, but that is far from the truth. Volcanoes spit lava, but also fine ash, rubble and big boulders. Up on the surface, they float around, settle and erode into each other, just as messy as other sediments.
Road cuts along the main road northwards from Teide tell such a story. Once, this must have been a lake or river, and a lava flow erupted into it from below. When the hot lava came in contact with the cold water it instantly solidified. But only the outer part, which became a thin shell with still hot lava inside. Then, a new blob of lava broke through and solidified, and another blob…until the lava had become a big bunch of rounded, hard blobs. We call them “pillow lava”, although you may find them a bit too hard for your bed.
In this road cut, the pillows have broken apart by later wear and tear, to individual blocks. A flow of ash has laid itself down above, probably as a thick flow that scoured down into the coarse, pebbly pillows below.
And for the finale: A dike of magma wedged its way to the top, cutting through all the other layers. It spread out fingers where it could find weaknesses in the rock. Finally, erosion cut its longest finger and then the whole thing got buried in more ash.
The final result looks a bit like the geology gives us the finger and says f**k off!
And now, I will do exactly that, leaving more of Teide’s paintings to the next blog post.