Investigación geofísica de los paleovalles pleistocenos del NE de Cataluña: el ejemplo de la Riera de Tossa (Costa Brava meridional)

The geometry of Riera de Tossa (Costa Brava, Catalonia) Pleistocene paleovalley has been studied by two geophysical prospecting methods: vertical electric sounding (VES-DC) and seismic refraction. The results show the existence of a sudden slope change of the thalweg that permits to differentiate two sections where erosion processes operated in unequal intensity. Based on geological and geomorphological available data, it can be inferred that this slope rupture is caused by the litological control imposed by the alineation of resistant materials, which limited the headward erosion extend of the creek during the Upper Pleistocene

Analysis of Pleistocene paleodrainage evolution in the Po Basin (Italy) by multivariate statistical techniques

In order to obtain a high-resolution Pleistocene stratigraphy, eleven continuously cored boreholes, 100 to 220m deep were drilled in the northern part of the Po Plain by Regione Lombardia in the last five years. Quantitative provenance analysis (QPA, Weltje and von Eynatten, 2004) of Pleistocene sands was carried out by using multivariate statistical analysis (principal component analysis, PCA, and similarity analysis) on an integrated data set, including high-resolution bulk petrography and heavy-mineral analyses on Pleistocene sands and of 250 major and minor modern rivers draining the southern flank of the Alps from West to East (Garzanti et al, 2004; 2006). Prior to the onset of major Alpine glaciations, metamorphic and quartzofeldspathic detritus from the Western and Central Alps was carried from the axial belt to the Po basin longitudinally parallel to the SouthAlpine belt by a trunk river (Vezzoli and Garzanti, 2008). This scenario rapidly changed during the marine isotope stage 22 (0.87 Ma), with the onset of the first major Pleistocene glaciation in the Alps (Muttoni et al, 2003). PCA and similarity analysis from core samples show that the longitudinal trunk river at this time was shifted southward by the rapid southward and westward progradation of transverse alluvial river systems fed from the Central and Southern Alps. Sediments were transported southward by braided river systems as well as glacial sediments transported by Alpine valley glaciers invaded the alluvial plain. Kew words: Detrital modes; Modern sands; Provenance; Principal Components Analysis; Similarity, Canberra Distance; palaeodrainage

Las cuevas prehistóricas de Serinyà (Pla de l’Estany, Girona)

The Reclau Caves, which form part of the Serinyà Prehistoric Caves Park (Pla de l’Estany, Girona), are shelters formed by waterfall travertines which have been in turn affected by karstification phenomena. Though relatively small, these cavities were big enough to held human occupation. Its evolution has seen the falling of blocks and infilling of terrigenous materials. Thus, the caves were completely filled and had most of their original roofs fallen. The first excavations of these caves were made in the mid 1940s and they continued, albeit with some interruptions, until present times. The caves were occupied by humans since the late Middle Pleistocene until the Holocene. Hence, the main occupation periods can be attributed to the Middle Paleolithic and Upper Paleolithic cultures. Given the existence of these sites, the project of an archeological park was started and its first phase opened to the public in the summer of 1997. The creation of this park has led to the protection of the three main caves of the site (Arbreda, Mollet and Reclau Viver Caves). The caves have also been adapted and singposted to open them to the public. Other facilities of the park include a reception building and an activity area. The caves can be visited in guided tours which include the projection of a film, the visit to the permanent exhibition room, the three main caves and the participation in some prehistoric-related activities

Dynamics and mixing in the Upper Ocean Layer

S'estudia la resposta de la capa de barreja oceànica al forçament atmosfèric considerant dades obtingudes durant 12 dies d'abril del 2001 a 42 estacions a través de l'Atlàntic nord seguint aproximadament la latitud de 53ºN. Aquestes dades inclouen, a més de variables atmosfèriques, mesures de CTD, velocitats amb ADCP i dades de microestructura obtingudes amb un perfilador de caiguda lliure. En aquest últim cas, s'han desenvolupat tècniques de processament de les dades que també es presenten aquí. El transsecte estudiat segueix la posició climatològica del rotacional mitjà anual del vent igual a zero i travessa el corrent del Labrador i algunes branques i meandres del Corrent Atlàntic Nord. El forçament atmosfèric es va caracteritzar per vents intensos i fluxos superficials de calor negatius, tot i que, tal com es dedueix de la comparació del gruix de la capa de barreja amb la longitud de Monin-Obukov, la barreja induïda pel vent va dominar sobre la convectiva durant tot el transsecte.