Relict periglacial soils on Quaternary terraces in the central Ebro Basin (NE Spain)

Pedofeatures associated with ancient cold climatic conditions have been recognized in soils on terraces in the Monegros area (central Ebro Basin, Spain), at a latitude of 41°49′N and an altitude of 300 m a.s.l. Eleven soil profiles were described on fluvial deposits corresponding to the most extensive terrace (T5) of the Alcanadre River, Middle Pleistocene in age (MIS8–MIS7). Each soil horizon was sampled for physical, chemical, mineralogical and micromorphological analyses. Macromorphological features related to pedocryogenic processes were described: involutions, jacked stones, shattered stones, detached and vertically oriented carbonatic pendents, fragmented carbonatic crusts, laminar microstructures, succitic fabric, silt cappings on rock fragments and aggregates, and irregular, broken, discontinuous and deformed gravel and sandy pockets. Accumulations of Fe–Mn oxides, dissolution features on the surface of carbonatic stones, and calcitic accumulations were identified related to vadose–phreatic conditions. The observed periglacial features developed under cold environmental conditions in exceptional geomorphic and hydrological conditions. This soil information may have potential implications in studies of paleoclimate in the Ebro Valley as well as in other Mediterranean areas

Secular trends in ocean tides: Observations and model results

During the last century the response of the oceans to tidal forces has changed significantly. This study focuses on an analysis of long‐term sea level records located in the Atlantic and Pacific, primarily in the Northern Hemisphere. It shows that changes of tidal amplitude and/or phase have taken place over large scales. The principal solar semidiurnal (S2) tide shows the largest trends. At some locations, the change in the mean tidal range due to tidal trends is significant compared with the trend in mean sea level. Thus, it might be advisable to consider these changes in studies of the impact of rising sea level. Numerical simulations of the principal lunar semidiurnal tide (M2) demonstrate a model sensitivity in the North Atlantic to changes in glacial isostatic adjustment and sea level rise, which captures 30–40% of the magnitude of the trends in observations. However, the spatial patterns do not agree well with those inferred from observations, suggesting that forward global models are currently useful for qualitative but not quantitative understanding of the observed trends. A global free oscillation synthesis indicates that sea level rise due to glacial isostatic adjustment leads to decreasing global resonant periods and increasing damping in the system and a coupled oscillator model shows that changes in sea level on the shelf are much more effective at perturbing shelf and ocean tides than sea level changes in the deep ocean.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84335/1/jgr_seculartrendsintides.pd