Leaders	Mercedes Ferrer Luis González de Vallejo   Email: vallejo@geo.ucm.es Julia Seisdedos
Dates	May 29th
Number of participants	20 minimum – 35 maximum
Cost	50 euros
Program	More than 20 mega rockslides have been described in Canary Islands. The resulting slided masses, deposited on the ocean floor, cover areas of thousands of square kilometres and volumes of hundreds of cubic kilometres. These paleo-landslides have been considered as one of the largest known in the world by their volume. Güímar and La Orotava valleys in Tenerife were originated by mega rockslides. Both constitute exceptional examples due to their geomorphological features and the fact that the slided deposits have been identified in the ocean floor and inside the galleries excavated in the island. The estimated (subaerial) volume of these rockslides is in the order of 50 km3. The age of Güímar rockslide has been estimated approximately 1 Ma and the age of La Orotava rockslide between 0.54 to 0.69 Ma. These valleys are 10 km wide and they present opposite orientations, ESE and NNW respectively. Their heads are located in the Cordillera Dorsal, main rift zone in the island with NE direction and maximum heights between 1700 and 2200 m. The morphological characteristics of the valleys are singular, outstanding the symmetry and the important height of the lateral scarps (500 m), formed by pre-landslide volcanic materials with slope angles higher than 35º. The depressions formed were filled by post-landslide volcanic materials with slope angles lower than 15º. The overall theme of the field trip is a presentation of Güímar and La Orotava rockslides, observing the geological and morphological features of the valleys and discussing about the mechanism and causes of the instability processes of the volcanic islands flanks. Detailed instructions and itinerary will be provided to registered participants. Field trip guide will be handed to participants onsite.