Seven million years ago
The oldest rocks to have been found on Tenerife are estimated to date from around 7 million years ago. Until then, volcanic matter from underwater eruptions had piled up, pushing the Island above the surface in what are now the regions of Teno and Anaga. Along with these two mountain ranges, Adeje is another of Tenerife's longest-standing areas in geological terms. These geological edifices appear to be aligned along huge fractures, which meant that the product of their volcanic eruptions gradually piled up like a roof. This first cycle in the Island's formation ended with salic emissions that now make up the top part of many of Anaga's peaks.
Three million years ago
The middle part of the Island was the focus of the volcanic eruptions that took place some three million years ago, which gradually contributed towards the outline of Tenerife we know it today. The volcanic fissure activity of that time produced basalt material, and there is evidence to suggest that it first formed a large dorsal ridge with greater concentrations of lava at either end, creating two breakwater-type structures that sheltered the intermediate area, which could be described as a sort of valley: today's valleys of La Orotava and Güímar. The most abundant materials found are trachyte and phonolite rock. Another interesting fact is that the end of this stage in the Island's formation culminated with the centre of Tenerife collapsing, which gave rise to the amphitheatre of Las Cañadas, although there are divergent theories regarding this event. It is from this crater that the Teide-Pico Viejo stratovolcano rose. Other theories, such as that upheld by Tenerife-born Telesforo Bravo in 1962, suggest that the valleys of Güímar and La Orotava were created by huge landslides.
Half a million years ago
Half a million years ago, Tenerife's inherent vulcanism began to create volcanic cones: Pico Viejo and Teide were formed in the crater on Las Cañadas, and new emission centres emerged around the Island covering the land around them and pushing back the sea. It was at this time that Tenerife acquired its current geography and appearance.