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The volcano-stratigraphic and geochronologic data presented in this work show that the Tenerife central zone has been occupied during the last 3 Ma by shield or central composite volcanoes which reached more than 3000 m in height. The last volcanic system, the presently active Teide-Pico Viejo Complex began to form approximately 150 ka ago. The first Canadas Ž . Edifice CE volcanic activity took place between about 3.5 Ma and 2.7 Ma. The CE-I is formed mainly by basalts, Ž . Ž trachybasalts and trachytes. The remains of this phase outcrop in the Canadas Wall CW sectors of La Angostura 3.5-3.0 . Ž . Ž . Ma and 3.0-2.7 Ma , Boca de Tauce 3.0 Ma , and in the bottom of some external radial ravines 3.5 Ma . The position of its main emission center was located in the central part of the CC. The volcano could have reached 3000 m in height. This edifice underwent a partial destruction by failure and flank collapse, forming debris-avalanches during the 2.6-2.3 Ma Ž . period. The debris-avalanche deposits can be seen in the most distal zones in the N flank of the CE-I Tigaiga Breccia . A new volcanic phase, whose deposits overlie the remains of CE-I and the former debris-avalanche deposits, constituted a new volcanic edifice, the CE-II. The dyke directions analysis and the morphological reconstruction suggest that the CE-II center was situated somewhat westward of the CE-I, reaching some 3200 m in height. The CE-II formations are well exposed on Ž . Ž . the CW, especially at the El Cedro 2.3-2.00 Ma sector. They are also frequent in the S flank of the edifice 2.25-1.89 Ma Ž . Ž . in Tejina 2.5-1.87 Ma as well as in the Tigaiga massif to the N 2.23 Ma . During the last periods of activity of CE-II, important explosive eruptions took place forming ignimbrites, pyroclastic flows, and fall deposits of trachytic composition. Ž . Ž Their ages vary between 1.5 and 1.6 Ma Adeje ignimbrites, to the W . In the CW, the Upper Ucanca phonolitic Unit 1.4 . Ma could be the last main episode of the CE-II. Afterwards, the Canadas III phase began. It is well represented in the CW Ž . Ž . Ž . Ž sectors of Tigaiga 1.1 Ma-0.27 Ma , Las Pilas 1.03 Ma-0.78 Ma , Diego Hernandez 0.54 Ma-0.17 Ma and Guajara 1.1 . Ma-0.7 Ma . The materials of this edifice are also found in the SE flank. These materials are trachybasaltic lava-flows and Ž . abundant phonolitic lava and pyroclastic flows 0.6 Ma-0.5 Ma associated with abundant plinian falls. The CE-III was essentially built between 0.9 and 0.2 Ma, a period when the volcanic activity was also intense in the 'Dorsal Edifice' situated in the easterly wing of Tenerife. The so called ' valleys' of La Orotava and Guimar, transversals to the ridge axis, alsö formed during this period. In the central part of Tenerife, the CE-III completed its evolution with an explosive deposit resting on the top of the CE, for which ages from 0.173 to 0.13 Ma have been obtained. The CC age must be younger due to Ž the fact that the present caldera scarp cuts these deposits. On the controversial origin of the CC centr...

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A simple theoretical model, based on the assumption that radon is transported by molecular diffusion combined with advective flow induced by barometric pressure, is used to investigate radon exhalation at three subsurface monitoring sites in the volcanic island of Tenerife, Canary Islands. The model is intended to filter out all known contributions to radon flux, in an attempt to find potential precursory signals of seismic and/or volcanic activity. For the period of observations (1 December 2000 to 1 April 2001), variations on radon concentration predicted by the model were in good agreement with those measured, confirming they were induced by atmospheric pressure changes.

La Cueva del Llano is a volcanic tube of Pleistocene age on Fuerteventura Island, in the Canary Islands. Part of it is infilled with sediments of external origin. These deposits are exceptional in stratigraphic complexity and thickness compared with other known tube infillings, and they comprise nine stratigraphic units deposited in five phases. In Phase I, which has not been dated, sedimentation of cinder from a nearby cone occurred. Phase II began ca. 16,830 ± 900 14C yr B.P., whereas phase IV dates to 9280 ± 370 14C yr B.P. The interpretation of sedimentary features shows that phases III and V correspond to a dry climate, similar to the present one, whereas the climate was much wetter during phases II and IV. This paleoclimatic sequence agrees with those suggested by the study of deposits formed in other sedimentary environments, not only in Fuerteventura but on other islands of the Canary group and the Sud-Maroc region.