La Gomera, with its 370 square kilometers and its 1487 meters of altitude in the Alto de Garajonay, is the second smallest island of the archipelago and the third lowest. It arose about 10-12 million years ago, when huge blocks of the oceanic crust emerged from the ocean floor and different volcanic episodes increased its size. Prolonged periods of rest allowed the action of erosion. The landscape of the island is closely related to the erosion of the waters that have criss-crossed an extensive network of gullies, among which can be highlighted the Vallehermoso, Hermigua or the spectacular Valle Gran Rey. The marine erosion has caused a major setback in its line of coast, carving cliffs of considerable heights (La Mérica), or stripping the rocks to show us fabulous geological formations (Los Órganos).
The jungles that upholster the summits of La Gomera have protected from erosion the horizontal basalts, a geological material on which is settled the largest part of the park, from where the ravines depart in radial form until they reach the sea, as if it was a giant orange juicer. The erosion over millions of years and the green mantle of the summits of La Gomera make it almost impossible to discover the features of the volcanic eruptive periods. An endless maya de taparuchas (cracks where the lava gushed out as if they were large scars) and Los Roques (solidified lava in the volcanic vent, exposed to our eyes when the volcanic cone was eroded as time went by), are two of the most characteristic geological traits of the island. Los Roques de Agando, Carmona, Ojila and Lla Zarcita give us a unique stamp.