This island’s volcanic origin confers upon it certain scenic peculiarities of great rarity. The main distinguishing feature of Gran Canaria volcanism is the superimposition of modern structures upon old, giving rise to myriad forms of cones, depressions and volcanic lava flows. The last-mentioned, rivers of solidified lava, are present in a variety seen in no other place on Earth.
The island is geologically divided into two zones: the south-western half, older and characterised by having undergone explosive episodes of immense force which account for the singular shapes of the rock spikes, veritable geological symbols of Gran Canaria; and the north-eastern half, younger and the site of more defined volcanic shapes, such as craters and black lava cones.
The former zone is outstanding for the presence of two gigantic basin-shaped volcanic depressions or calderas (caldera: cauldron): the Tirajana Caldera, caused by erosion, and the Tejeda Caldera, 15 kilometres in diameter and born of the sinking of a volcanic structure, which can be seen in all its majesty from the Cruz de Tejeda look-out point. Highlights in the other zone are the Arucas, Gáldar, Guía, La Isleta and Bandama volcanic cones, as well as the Pinos de Gáldar, Los Marteles, Pino Santo and Bandama craters.