Emergency Geoarchaeology in an urban context

Within the scope of construction work conducted within an urban context for the creation of new buildings located in Rua das Olarias in Leiria, a selection of historical and archaeological remains attributable to different time periods were found. Such findings include; Levallois chips, ovens and modern or sub-modern ceramics, and a burial zone. Due to the presence of Palaeolithic evidence, the DGPC (Direção-Geral do Património Cultural) has requested a more in-depth analysis of the sedimentary deposits.

Geomorphologically, the area of intervention is located in the zone of the Typhonic Valley associated with the diapiric structure of Leiria-Parceiros, which is in the proximity of the Doleritic outcrop, where the Castle of Leiria was constructed. Concerning the stratigraphic-sedimentary component, from what was so far observed in the intervention carried out in the 3 sections researchers were able to identify that the sedimentary deposits of the area are composed, at the base, by marly and clayey layers (probably corresponding to the formations of the Dagorda Margas, from the Mesozoic), these are apparently "in situ" and are identified in the Geological Map (23C -Leiria).

It was not possible to identify layers of Neogene however, unconsolidated deposits were observed throughout the area with sedimentological characteristics which appear to be deposits of overburdening and flattening due to actions which took place in recent times. Most of the surface area of interest corresponds to the landform surface of the anthropic formation, where the deposits are thought to result from pottery activities (there is presence of clays and ceramics).

In the area of active archaeological intervention, coarser sediments were noted, but the more clastic deposits do not appear to have associated structures. So far it has not been possible to confirm the presence of a geological level to which the origin of the prehistoric archaeological material could be attributed.

Thus, the sampling program (sedimentological and palaeoenvironmental) will be oriented towards the recognition of possible natural Pleistocene layers (alluvial and fluvial deposits), the distinction between these, Mesozoic layers and layers of anthropic deposits. The methodology of sediment collection for geoarchaeological and palaeoclimatic purposes (in particular for sedimentological and palynological analyses) will follow established scientific procedures.  These analyses and further information about the terrain will only be possible with the help of sedimentological and palaeoenvironmental studies.