The principal structures in Tenerife, make the central highlands, with the Teide-[[Pico Viejo]] complex and the Las Cañadas areas as most prominent. It comprises a semi-[[caldera]] of about in area, originated by several geological processes explained under the Origin and formation section. The area is partially occupied by the Teide-Pico Viejo strato-volcano and completed by the materials emitted in the different eruptions that took place. A known formation called Los Azulejos, composed by green-tinted rocks were created by hydrothermal processes.