The Canary Islands, or rather the easternmost of them, were twice depopulated in the early modern era. Spanish exploitation and disease wiped out most of the islands’ indigenous Guanche population in the 15th and 16th centuries. The Earth itself drove Spanish colonists from the island of Lanzarote in the 18th century. Following a series of premonitory earthquakes, on 1 September 1730 magma began to erupt into the western region of Lanzarote. It continued to do so, from what eventually grew into ten different sites, until sometime in late 1735 or early ‘36. In some cases the eruptions formed cinder cones; in others lava simply poured onto the island’s surface, destroying fields and villages. Lava fields eventually covered a quarter of the island, and a thick layer of ash accumulated everywhere. The inhabitants stayed put through the initial eruptions, but cleared out after six new vents and cones formed in early 1731. They would not return for five years.
Upon their return, Lanzarote’s settlers realized that while the volcanic episode had destroyed their farms, it had also left them with a new resource: millions of magma pebbles, or lapilli, that could serve as an excellent inorganic mulch. Lanzarote was (and is) an arid land whose soil was unable to retain much moisture, but a thin layer of lapilli trapped water vapor from daytime onshore breezes, allowing plants to flourish. The island’s farmers began cultivating new crops, particularly grapes, raising them in sunken circular beds surrounded by low stone curbs. These beds protected crops from both excessive sunlight and wind, while ash and pumice mulch helped them retain water. By the second half of the century the island became an exporter of wine, including Malvasia Volcanica, a sherry for which it is still famous. Lanzarote's post-volcanic farms also produced vegetables, potatoes, and maize, thirsty crops for an island that sometimes gets less than 6 inches of rain per year.
There were limits, however, to how little rainfall the island's crops and farmers could survive. The agricultural boom on Lanzarote caused the island's population to double in thirty years, from 5,000 to 10,000 inhabitants. Then in 1768 a severe drought caused crops to fail and families to starve. Spanish officials responded by relocating settlers from Lanzarote to other parts of Spain's empire, including the colony of Texas. There Canarians became some of the first white settlers in San Antonio, exchanging the natural dangers of their old homeland for the manmade perils (like Comanche raids) of the new. Empire is not as immediately disruptive as rivers of fire and showers of ash, but in the longer term it is equally indifferent to humans’ well-being.
Sources: “The Legacy of Lanzarote,” Volcano Cafe, 23 Oct. 2021; Carol Greentree, “Lanzarote: Agriculture as Art,” Pacific Horticulture (n.d.); Fred Pearce, "How Volcanoes Launched Lanzarote's Bizarre Agricultural Revolution," Beacon Broadside, 5 June 2018; Valentin Troll et al, “Volcanic Particles in Agriculture and Gardening,” Geology Today 33 (July-August 2017: 148-54.








