A field trip and symposium were organized on behalf of the IGU Commission on Climate Change and Periglacial Environments from 26–29 August 1998 in Portugal, in conjunction with the IGU Regional Conference that took place in Lisbon (30 August –2 September). The field trip was dedicated to the glacial and periglacial geomorphology of the Serra da Estrela, and was organized by Antonio de Brum Ferreira and Gonçalo Teles Vieira (Centro de Estudos Geográficos, University of Lisbon). Thirteen visiting participants from Italy, The Netherlands, Canada, Belgium, Brazil, Denmark and Spain attended.
The highest mountains in Portugal (Serra da Estrela,1993 m asl) were glaciated by an ice cap and several valley glaciers during the Weichselian. The field trip focused on relict glacial and periglacial phenomena. The main aspects of the Pleistocene glaciation were presented and observed. Visits to periglacial sites included the observation of the head deposits of Sao Gabriel, the screes of Várzea do Crasto, the stratified coarse sand deposits of Barroca de Agua, and the Alto da Pedrice blockslope. The latter site presents a significant relict macrogelivation. The age of the deposit, its genesis and environmental conditions were discussed. Present-day cryogenic processes and their relationship with hydric and aeolian processes were also treated. The geomorphological significance of wind in the plateaus was observed in the Cantaro Raso and Fraga das Penhas areas.
In a marginal periglacial environment like the Serra da Estrela, with a Mediterranean climate where annual precipitation averages 2500 mm and mean annual temperature in the summit regions is 3–4°C, the present-day geomorphological dynamics are the result of the complex interaction between different processes (e.g. needle ice, deflation, runoff). Therefore it is difficult to attribute a single genetic mechanism to most of the observed features (e.g. coarse sand accumulations, incipient patterned ground, vegetation crescents).
On the afternoon of 29 August a symposium on Periglacial Landscapes: Their Development, Preservation and Climatic Significance was held in the Faculdade de Letras (University of Lisbon). Jef Vandenberghe chaired the session and presented a report on climatic control of periglacial river patterns. Six oral presentations followed, divided in two groups: Mediterranean and tropical areas, and high latitude areas. The symposium provided the opportunity for discussions among researchers from different areas and resulted in valuable suggestions for future research. The significance of the marginal mountains and of their sensitive and complex geomorphic responses to climate was emphasized.
Gonçalo Teles Vieira (email@example.com)