Geoarchaeology of El Bebedero site (Lanzarote, Canary Islands)

Abstract

The island of Lanzarote can be considered as an arid environment (UNESCO IA = 0.14), so the impacts produced by its early inhabitants triggered significant soil erosion. The sedimentological study of layers taken from the El Bebedero archaeological site gives enough evidence for this theory. The application of different techniques, including grain–size analysis, chemical features, geochemistry and 1 4C dates provides some information allows to get some geoarchaeological conclusions. In this sense, the stratigraphical cross-section shows five different layers presenting archaeological richness the number 5 (just the upper member), the 4 and the 3. The upper member of number 5 stratum and the number 4 include some remains – pottery, glass and metals- with roman features. An increase of grain-size mean along with more carbonates, phosphoric oxide, and other data indicate significant soil degradation, produced by overgrazing of goats and sheeps (bones of theses animal are abundantly present) from the 1st Century B.C. to the 3rd Century A.D. The strata number III was developed during a long time period, since the 3rd Century A.D. to the 14t h Century A.D. In addition, data provided by the palaeontological studies confirm an ecological crisis produced by the introduction of domestic animals and others species –as the rats –. These data show a very important environmental degradation induced by the human activities from the 1st Century B.C. to the 4th Century A.D., being it more moderated since the 4th to the 14th Century A.D. The occurrence of recent alluvial infilling in some of the valleys of the island (i.e., Femes and San José valleys) could indicate that soil erosion phase was produced all over the island. Actually, we are involved in a new research projects to get consistent evidence of this last theory.