Lanzarote is the easternmost island of the Canaries, less than 100 miles (about 150km) off the coast of Morocco. It is part of Spain, but not officially in the European Union and Pico Partido is a sharp, prominent peak near the centre of the island, between the small town of Mancha Blanca and the volcano of Timanfaya. The name means “divided mountain”, so called because the high peak is split by a deep fissure that seems to chop it in two. And it is enthralling. It is a basket of volcanic jewels to be treasured, particularly after the disappointment of the lack of access to Timanfaya itself (of which, more later). And Pico Partido is accessible, unlike much of the island where too many roads have no lay-bys or even a patch of cinder where you can pull in and explore.
The geology of Lanzarote
Lanzarote, with its volcanoes, is sitting on the tectonic plate that forms most of Africa. It is not near the edge, so it is not formed by one plate sinking under the other. Nor is it above a rising mass of magma, a hot spot. A little surprisingly, it is on a line of fractured rocks that stretches to the Atlas Mountains in North Africa, and further over to the European Alps.
The fractures formed, and are still moving, as a result of the stresses created as the African plate collides with the European plate. The volcanoes rose through the old sea bed about 2,600m below. For around 30myrs, the undersea eruptions built up until they broke the surface about 14mya, in the middle of the Miocene. Eruptions have been sporadic ever since, sometimes pouring vast amounts of lava from a series of fissures for several years. At other times, there were huge explosive eruptions. Landscapes were formed, eroded and buried repeatedly. The whole picture is extremely complex, especially as the chemical make-up of magma chamber seems to be unusually varied, giving rise to many different kinds and compositions of lava.
The history of volcanism on the island
There had been no eruptions in historic times and, in fact, a period of calm had lasted for several hundred thousand years. Therefore, one night in 1730, the sudden mass of eruptions down the centre of the island came as a huge surprise to the unfortunate islanders. Over the next six years, at least 50 volcanoes erupted, some explosively, others with fast-running lava that swept over 26 villages and fertile farmlands. A quarter of the island was destroyed as the volcanoes competed to bury and overflow each other with lava and ash. Timanfaya began on 1 September 1730 and ended on 16 April 1736, one of the longest-erupting vents on the island.
Pico Partido had a much briefer life, beginning on 10 October 1730, and ending less than four months later, on 1 January 1731. So, if you’re up there on the 10 October, you can sing “Happy Birthday” to a mountain. How do we know? The priest of Yaiza village wrote lengthy eyewitness descriptions of the whole thing and his informative writings are supported by the official accounts of the local municipal authority.
Pico Partido created three linked cones, each having periods of explosive activity with ash and cinders, pouring lava from tight vents, or filling their craters with lava lakes that overflowed their lips into the surrounding countryside. Cracks in the walls of the volcano filled with lava and erupted as small side vents. As the lava rose through the cracks, the gas within it expanded and blew out the top-most lava, spitting it out onto the surface. This built up around the vent, forming tall, steep-sided mini-volcanoes known locally as “hornitos” (Spanish for “little ovens”). They are also called “spatter cones”, because of the way the gas spat out the lava. Several are seen on the flanks of Pico Partido, and more around Timanfaya. Further afield, some really good ones can be seen at Los Muchachos on another Canarian Island, La Palma, and at Fleener Chimneys in Lava Beds National Park, in the western USA. Here, on Lanzarote, the main lava flows are often crusted over, with the lava continuing to flow below the surface. The surfaces would sometimes collapse, leaving channels and caves, or “lava tubes”. Several such tubes and channels are found around Pico Partido.
The landscape around Pico Partido still looks almost as fresh and newly-formed as it did in the eighteenth century, because there is so little rain to cause erosion or support the growth of vegetation. But this mountain has been quiet since 1731. There has not been any volcanic activity anywhere on Lanzarote since 1824, when there was a little series of eruptions. The last one, Tinguatón, erupted for only eight days in October 1824. Now, the only signs of life are the thermal hot-spots buried within several mountains, including of course, Timanfaya. In the restaurant at the top of Timanfaya, they use the heat from the lava to grill chickens, set fire to brushwood and make fake steam spouts for tourist entertainment, just to prove it really is hot just below the surface.
So, they’re not expecting an eruption soon? Maybe not, but neither were they expecting anything to happen in 1730, the day before the start of the second-longest eruption in recorded history (after Pu’u O’o in Hawaii). Incidentally, the Lanzarote volcanoes were spewing lava from a 14km-long fissure, the third-longest known (after those at Laki in 1783 and Eldgja in 934, both in Iceland).