Abstract Sediments at Pias (Galicia) provide evidence of Upper Pleistocene glacial activities at a valley junction in the north-western mountains of Spain. The sedimentary sequence consists of lower, predominately fine-grained lacustrine deposits with few lonestones, overlain by poorly sorted, sandy gravels interstratified with massive diamicton deposited during mid-Weichselian times (MIS 3) (marine isotope stage 3). The lacustrine sediments were deposited in a glacial valley temporarily dammed by a confluent glacier. The presence of active ice is suggested by massive diamicton layers best interpreted as till, rafted sediments in lacustrine deposits and deformation structures indicative of loading and kettle formation. Frozen ground conditions are suggested by a few involution-like structures. The Pias area contains one of the few western-Spain sedimentary records of Upper Pleistocene glaciation at relatively low latitude (about 42°N) and low altitude (less than 1000 m a.s.l.). A southern dip of the Polar front to 40–45°N latitudes, as occurred during Last Glacial Maximum, could have cut moisture to the northern Fennoscandinavian ice sheets. At the same time, however, sufficient precipitations would have persisted in north-western Spain to sustain extensive ice caps and their outlets to elevations as low as c. 900 m a.s.l.

Abstract: Late Messinian (Miocene) strata of Tuscany contain a valley fill 60 m thick and 2 km wide that can be traced for 8 km. The valley was cut in lacustrine clays and filled with boulder to pebble gravels from debris-charged flows. Upvalley outcrops comprise stacked sheets of poorly sorted and locally imbricated gravel deposited within shallow channels. Downvalley outcrops comprise thicker channel fills of imbricated finer gravel with abundant foresets formed by in-channel bars. Clasts of tourmaline-bearing aplite (eurite) in the valley fill match outcrops on Elba Island 60 km to the southwest, where eurite forms part of an intrusive complex that predates the valley fill by about one million years. The mapped valley trend and northward paleoflow confirm an Elba source. We infer that tectonomagmatic doming at Elba resulted in high relief, landscape dissection, and an abundant sediment yield that included eurite clasts. Subsequent doming associated with the younger Larderello and Amiata intrusions on the Tuscan mainland has reversed the drainage, and modern valleys drain westward to the Tyrrhenian Sea. Intrusive centers such as those of Tuscany, with a period of activity of hundreds of thousands to a few million years, may generate domes tens of kilometers in diameter and several kilometers high that reorganize drainage patterns and create valley fills. In the absence of volcanic clasts in the Neogene gravels, the eurite clasts provide the only evidence that links magmatism to valley dynamics.