Walking on Tenerife. Paddy Dillon

      El Teide vents hot gases and steam from fumaroles; this one is very close to the summit (Walks 37–40)

      The African landmass is the visible part of a continental plate that extends into the Atlantic Ocean, but the Canary Islands lie within the oceanic crust of the eastern Atlantic Ocean, close to the passive junction with the African continental plate. It is thought that the islands now lie directly above a hot-spot, or mantle plume, some 2500km (1550 miles) deep within the Earth. The mantle plume is fixed, but the oceanic and African plates are drifting very slowly eastwards. Every so often a split in the oceanic crust opens above the mantle plume, allowing molten rock to vent onto the ocean floor. As more and more material erupts, it piles higher and higher until it rises from the sea. Each of the Canary Islands was formed this way.

      Lanzarote and Fuerteventura were the first Canary Islands to form, and were subsequently pulled eastwards. The next time a rift opened over the mantle plume the islands of Gran Canaria and Tenerife were formed, and these were in turn pulled eastwards. A further oceanic rift led to the formation of La Gomera, La Palma and El Hierro. Looking forward in geological time more islands will appear as other rifts are torn open in the future.

      The forces at work deep within the Earth can scarcely be imagined. Every single piece of rock throughout the Canary Islands once existed in a molten state. Consider the energy needed to melt one small stone, and multiply that to imagine the energy required to melt everything in the island chain, as well as the immense amount of rock beneath the sea that supports them all!

      Over time huge amounts of volcanic material were piled high, but erosion has led to great instability. During recent geological time vast chunks of the islands have collapsed into the sea, creating features such as El Golfo on El Hierro, the Caldeira de Taburiente on La Palma and the Orotava valley on Tenerife. With each catastrophic collapse, tidal waves devastated places around the Atlantic Ocean. Some geologists believe that the steep, bulging northern slope of El Teide could collapse during any future volcanic eruption.

Wildlife

      Plants and flowers

      While the northern hemisphere was in the grip of an Ice Age, the Canary Islands were sluiced by rainstorms, with powerful rivers carving deep, steep-sided barrancos into unstable layers of ash and lava. As the landmasses emerged from the Ice Age the Canary Islands dried out and the vegetation had to adapt to survive. Some species are well adapted to semi-desert conditions, while on some high parts of the islands, laurisilva cloud forests are able to trap moisture from the mists and keep themselves well watered. Laurisilva forests once spread all the way round Mediterranean and tropical regions, and extensive examples of these forests thrive on Tenerife.

      Canary pines flourish on high, dry mountainsides, sometimes in places where nothing else grows. A collar of pine forest, known as the Corona Forestal, surrounds the highest mountains on Tenerife. Almost every pine you see will have a scorched trunk, but they regenerate surprisingly well after forest fires. Beware of the long pine needles on the ground, as they are slippery underfoot. Canary palms also flourish in dry places, and in the past every part of the tree had a use; today they provide delicious miel de palma, or palm syrup. Every so often dragon trees occur, the last surviving descendants of the ancient prehistoric forests. They have been decimated in the wild but prove popular in gardens.

      Tagasaste trees are often found in dense plantations, always in places where livestock are grazed. They grow with little water, yet have a high nutritional content and are regularly cut for animal fodder. In recent years they have been exported to Australia. Junipers are common; fruit and nut trees have been established, including apples, oranges, lemons, bananas, almonds, figs and vines. The introduced prickly pears are abundant, not so much for their fruit, but for raising cochineal beetles, whose blood provides a vivid red dye.

      Bushy scrub is rich and varied, including sticky-leaved cistus and a host of species that walkers should learn to identify. These include bushy, rubbery tabaibal and the tall cardón, or candelabra spurge. Both have milky latex sap, as does tangled cornical, with its distinctive horned seed pods, which creeps over the ground and drystone walls. Aulaga looks like a tangled mass of spines and is often found colonising old cultivation terraces in arid areas. Aromatic, pale green incienso is a bushy plant that, with salado, grows densely on the arid lower slopes of the islands. The fragrant Canarian lavender usually grows in arid, rocky, stony areas among other scrub species. Few of the plants have common English names, but all of them feature so often that they should be learned.

      Flowers grow all year round, but visitors in spring and early summer will be amazed at the colour and wealth of flowering plants. Many are Canarian endemics, and even trying to compile a shortlist would be pointless. Anyone with a particular interest in flowers and other plants should carry a specific field guide, in English. Try Native Flora of the Canary Islands by Miguel Ángel Cabrera Pérez, Editorial Everest or Wild Flowers of the Canary Islands by David Bramwell and Zoë Bramwell, Editorial Rueda.

      Animals

      As befits remote islands created in relatively recent geological time, the main animal groups to colonise the land were winged creatures, insects and birds. The largest indigenous land mammals were bats. Large and small lizards also arrived, possibly clinging to driftwood. The laurisilva cloud forest is home to the laurel pigeon, while the rock pigeon prefers cliffs. Buzzards and kestrels can be spotted hunting, and ospreys are making a slow come-back. Ravens and choughs are common in some places. There are several varieties of pipits, chaffinches, warblers and chiffchaffs. One of the smallest birds is the kinglet, a relative of the goldcrest. There are canaries, which have nothing to do with the name of the islands, and parakeets that add a flash of colour. The islands attract plenty of passage migrants, as well as escapees from aviaries. The coastal fringes are colonised by gulls, but it is best to take a boat trip to spot shearwaters or storm petrels, as they spend most of their time on open water. Boat trips are also the way to spot a variety of dolphins and whales.

      Once the Guanche people arrived and colonised the islands over two thousand years ago, the forests suffered as much from clearance as from grazing by voracious sheep and goats. Following the Conquest in the 15th century, the Spaniards brought other domestic animals; of these the cats had a particularly devastating impact on the native wildlife, practically wiping out giant Canarian lizards, which have only recently been rescued from the edge of extinction. The largest lizards on Tenerife are slightly speckled with blue. Rabbits chew their way through the vegetation and appear regularly on Canarian menus.

National Parks