Geography of La Palma

Known as the "isla bonita" or "green island" for its abundant vegetation, La Palma is, together with El Hierro, the youngest island in the Canary archipelago: both are still in the juvenile shield-building phase, the fastest stage of growth of an oceanic island. Located at the north-western end of the Canaries, it is the most oceanic of them all, and that position exposes it more frequently to Atlantic storms, making it the island with the highest rainfall. It is shaped like an inverted teardrop: its long axis stretches some 46 kilometres between Punta Juan Adalid and Fuencaliente, its maximum width is around 26 kilometres, and it culminates at 2,426 metres at the Roque de los Muchachos. Few islands pack so much relief into so little surface, and from that disproportion spring the extreme slopes and deep ravines that define its landscape.

The heart of the island is the Caldera de Taburiente, an immense depression some eight kilometres across with drops of up to 2,000 metres, which has given its name universally to volcanic calderas. Declared a National Park in 1954, it shelters one of the best-preserved pine forests in the Canaries, covering some 4,690 hectares, protected in large part thanks to the irrigators of the Heredad de Argual y Tazacorte, historically interested in preserving the aquifer. Its walls generate a network of streams and torrents of intense water erosion that prevents soil formation, and the whole amphitheatre drains to the sea through the Las Angustias ravine, the Caldera's great natural outlet, whose waters irrigated the crops of Argual, Tazacorte and Los Llanos from the sixteenth century onwards.

Science has reconstructed the origin of this monumental landscape. The geological studies of Juan Carlos Carracedo and his collaborators on La Palma and El Hierro show that the Caldera is not a giant crater, but the combined result of a giant landslide and erosion: some 560,000 years ago the western flank of the Cumbre Nueva ridge collapsed into the sea and opened the depression now occupied by the Aridane Valley; the Bejenado volcano later grew over the scar, and a ravine entrenched along the landslide fault gradually widened until it carved out the present Caldera. The north of the island, much older, has not been rejuvenated by modern eruptions, and there runoff has carved deep ravines arranged radially from the summit of Los Andenes.

At the highest point of that amphitheatre of summits stands the Roque de los Muchachos, at 2,426 metres, home to the astrophysical observatory that has made La Palma one of the most prestigious astronomical centres in the world, favoured by clean, protected skies offering unbeatable conditions for observing the stars. At these heights a high-mountain climate reigns: snow usually falls on the rims of the Caldera in winter, and the vegetation culminates in an open forest of Canary cedar and a summit scrub dominated by the retamón, with endemics as rare as the La Palma violet or the guanche rose.

The southern half belongs to the Cumbre Vieja ridge, a young volcanic axis whose landscape has been shaped by recent eruptions, many of them historical, and is barely eroded: in its permeable materials water infiltrates leaving hardly any runoff, so that the drainage networks here are mere incisions. It is the volcanically active sector of the island, where San Antonio erupted in 1677 and Teneguía in 1971, and where on 19 September 2021 the Cumbre Vieja eruption opened in the Cabeza de Vaca area, in El Paso, lasting 85 days until 13 December and transforming the Aridane Valley once again. The contrast between the old, eroded north and the young, volcanic south is the key to reading the whole of La Palma's relief.

The trade winds explain the island's other great wealth: water. The highest rainfall figures in the Canaries are recorded on La Palma's north-east-facing side, where between 500 and 1,500 metres of altitude more than 1,000 litres per square metre fall each year. The frequent rainfall and the permeability of the terrain historically fed abundant springs, such as those inside the Caldera or those of Marcos y Cordero, in the Barranco del Agua: until the nineteenth century the island naturally produced some twenty cubic hectometres a year, although the boreholes later drilled for irrigation depleted the springs. In those humid mid-altitudes the laurel forest thrives, and the monteverde of Los Tilos, a forest inherited from the Tertiary era, was declared a Biosphere Reserve, a distinction later extended to the whole island.

The coast is mostly cliff-lined and the verticality of the relief historically hindered the installation of harbours, which did not prevent Santa Cruz de La Palma, founded in 1493 by the adelantado Alonso Fernández de Lugo, from becoming a first-rate Atlantic port. Today the island's population, stabilised at around 80,000 inhabitants, is concentrated in two towns of some twenty thousand residents each: Santa Cruz de La Palma, the capital, on the east coast, and Los Llanos de Aridane, in the fertile western valley opened by the ancient landslide. Banana plantations occupy some 4,000 hectares distributed between the two slopes, and next to them lie the main tourist enclaves, Los Cancajos and Puerto Naos. At the southern tip, the salt pans and lighthouse of Fuencaliente close, between recent lava flows and black-sand beaches, the map of an island that is still growing.