THE PARTICULAR ASPECT OF PLEISTOCENE POLLEN FLORA FROM THE WEST COAST OF PORTUGAL

There are numerous deposits rich in organic matter outcrop in several places in the cliffs between Ferrel and Lagoa de Obidos on the west coast of Portugal. At this site pollen has been studied from 4 specific sections: Olhos de Água, Fincha Grande, Vale Benfeito and Vale de Janela. Palynological studies show that trees and herbs are poorly represented except for Pinus, Ericaceae and Myrica and at some levels Myrtus, Betula Quercus and Ilex. The Mediterranean facet is represented by Olea, Q. ilex-t., and Cistaceae. The diagram of Vale de Janela shows the progressive installation of arboreal vegetation without, however, complete forest cover. It could be an open vegetation in a coastal area affected by the relatively damp, windy climate. Pollen analysis of Fincha Grande has identified 40 taxa, with Quercus the most dominant in the upper part, replaced by Betula and then by Pinus. Saxifraga, a temperate or sub-Arctic element, is present at the top of the diagram and Lygeum a Poaceae from the Mediterranean steppes in the middle. At Vale Benfeito, Betula is well represented and Quercus is present at Olhos de Água. Based on pollen flora and radiocarbon dating (35,000 to 45,000 years BP) these sites have been dated as Pleistocene. Paleo-floristic data obtained is in agreement with the meridional location of these deposits on the Atlantic coast and indicates the buffer role played by the ocean. Observation of Myrica, Myrtus, Ilex, Olea, Quercus ilex-t would seem to indicate that this coastal zone was a sort of refuge, with heath and a foggy, Atlantic climate. There would also be areas protected by arboreal vegetation that formed a complex ecosystem clearly showing the particular aspects of Pleistocene flora in Portugal.