TILL MACROFABRIC ANALYSIS OF GLACIAL DEPOSITS IN THE SOUTHERN SERRA DO GERES MOUNTAINS, NW IBERIAN PENINSULA

Till macrofabric and grain-size analysis of glacial diamictons and sequences present in several valleys of the Southern Serra do Gerês Mountains in the Northwestern Iberian Peninsula were used to interpret till types and to reconstruct the glacial paleoprocess history of this mountainous region. Subglacial lodgement and supraglacial melt-out tills are dominant in the southern portion of this range. Subglacial lodgement tills, representative of periods of glacial advance in several valleys followed by stability, present cluster fabrics and generally poorly sorted and fine sediments. Supraglacial melt-out tills, representative of periods of glacial stability with some minor readvancements followed by recession, present weaker fabric data and coarser, poorly sorted sediments. These glacial diamictons and sequences are of particular importance in the reconstruction of the glacial dynamics and history of the Southern Serra do Gerês Mountains due to poor preservation of glacial landforms related to the Last Glacial Maximum in several glaciated valleys.