Completando el mapa de la Cuenca del Ebro: el Mesolítico del IX milenio cap BP de Espantalobos (Huesca, España)

Abstract

This paper presents the results of the first archaeological campaign in Espantalobos, a new Mesolithic site in the Ebro Basin. Located next to the city of Huesca, it helps to improve our knowledge on the prehistoric occupation of plains, non-mountainous areas, which in the central Ebro Basin have suffered a deep transformation in historic times due to agriculture and erosive processes related to anthropic deforestation. Its main contribution to the prehistoric research is the archaeological confirmation of the occupation by groups of hunter-gatherers of lowland areas during Mesolithic times. The site is a dismantled sandstone rock-shelter that shows two different human occupations. The most recent archaeological layer (level c) is related to the Geometric Mesolithic: its lithic industry is based on laminar elements, which were brought to the site already knapped, and some retouched elements, mainly elongated trapezes and microburins, typical of the first Geometric Mesolithic moments in the Ebro Basin. However, the scarce elements from the former level e, just two geometrics and some notched flakes, make difficult to ascribe the occupation to this phase or to the previous Denticulate Mesolithic. In both periods lithic raw materials could have been collected in nearby areas, barely 30 km to the south of the site, where outcrops of a good-quality "Monegros-type" flint are known. Prehistoric people also knapped non-siliceous local rocks to obtain flakes, which were used untransformed. They also profited these boulders and pebbles to obtain heavy, resilient tools (choppers, rabot). Despite the poor conservation of the site -strongly affected by quarrying activities and erosion-, an interesting toolkit has been found, as well as some faunal remains and a copious lot of charcoals whose anthracological data can partially replace the missing pollen analysis, which is not conserved in the sediment. In this type of shelters bad conservation of bone assemblage is usual: a poor sample of Capra, Cervus and Oryctolagus has been identified, many of them cremated on purpose, while an ibex bone presents a cut mark. The radiocarbon dates place the human occupations in the Early/Middle Holocene: level e (8975-8547 cal BP) coincides with the final phases of the Climatic Optimum, and level c (8321-8046 cal BP) fit with the interesting dry and cold 8.2 event. After this data, level e could be- long either to a final Denticulate Mesolithic or to an early Geometric Mesolithic: as far as we know, this last period starts around these times in the left bank of the Ebro Basin. Concerning charcoals, a first approach to their comprehensive study is offered. Level c could reflect the 8.2 event by the retrocession of mesophilous taxa and the increase of xerophilous species compared to level e, being conifers (Pinus and Juniperus) the most frequent taxa in both layers, in an open landscape previous to the expansion of the Quercus genera. Espantalobos could be interpreted, like other small rock shelters with similar occupations, as a seasonal settlement, dedicated to exploit one or more specific resources (still not determined), repeatedly occupied by a small party of people. Espantalobos, like Cabezo de la Cruz campsite in the Huerva Valley, confirms the presence of Mesolithic people in the currently eroded and humanized plains of the central Ebro Basin. It helps to articulate a growing network of prehistoric sites that make this region one the best areas in Iberia to study the Early/Middle Holocene.