The Mesolithic–Neolithic transition in southern Iberia

New data and a review of historiographic information from Neolithic sites of the Malaga and Algarve coasts (southern Iberian Peninsula) and from the Maghreb (North Africa) reveal the existence of a Neolithic settlement at least from 7.5 cal ka BP. The agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the Mesolithic populations. The timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems, including upwelling intensity, sea-level changes and increased aridity in the Sahara and along the Iberian coast. These changes likely impacted the subsistence strategies of the Mesolithic populations along the Iberian seascapes and resulted in abandonments manifested as sedimentary hiatuses in some areas during the Mesolithic–Neolithic transition. The rapid expansion and area of dispersal of the early Neolithic traits suggest the use of marine technology. Different evidences for a Maghrebian origin for the first colonists have been summarized. The recognition of an early North-African Neolithic influence in Southern Iberia and the Maghreb is vital for understanding the appearance and development of the Neolithic in Western Europe. Our review suggests links between climate change, resource allocation, and population turnover.     

Holocene environmental change in southern Spain deduced from the isotopic record of a high-elevation wetland in Sierra Nevada

Small lakes and wetlands from high elevation within the Sierra Nevada Range (southern Spain) preserve a complete post-glacial Holocene record. Isotopic, TOC and C/N analyses, carried out on a sediment core, show various stages in the evolution of the Borreguiles de la Virgen, which today constitute a small bog at about 2,950?m above sea level. Glacial erosion generated a cirque depression, which became a small lake during the first phase of infilling (from?8,200 to 5,100?cal?yr BP), as suggested by sedimentary evidence, including an atomic C/N ratio generally below 20, low TOC values and the highest ??¹³C and ??¹⁵N values of the record. These results imply significant algal productivity, which is confirmed by the microscopic algal remains. Drier conditions became established progressively in this area from?5,100 to 3,700?cal?yr BP. Subsequently, the lake evolved into a bog as shown by geochemical evidence (C/N ratios above 20, high TOC content and low ??¹³C values). Unstable conditions prevailed from?3,600 to 700?cal?yr BP; an extremely low sedimentation rate and scarcity of data from this period do not allow us to make a coherent interpretation. Fluctuating conditions were recorded during the last?~700?cal?yr BP, with wetter conditions prevailing during the first part of the interval (with C/N rate below 20) up to 350?years ago. In general, a gradual trend toward more arid conditions occurred since?~6,900?cal?yr BP, with a further increase in aridity since?~5,100?cal?yr BP. This evidence is consistent with other contemporaneous peri-Mediterranean records.     

Extreme wave climate changes in Central-South America

The spatial and temporal variability of extreme wave climate along the Central-South American continent is analyzed. The study evaluates changes in the intensity of extreme significant wave height (SWH) throughout the year over the 1980–2008 period, using a calibrated long-term wave reanalysis database forced with NCEP/NCAR reanalysis. A non-stationary extreme value model, based on monthly maxima with a new approach for long-term trends, has been applied. Results show a common positive trend in the Pacific basin throughout all seasons and a significant decreasing trend pattern in the area of Surinam and north of Brazil, on the Atlantic border (up to ?1.5 cm/year in March–April–May). A higher increase of the extreme wave heights is found in the austral summer (December–January–February) at Tierra de Fuego and the Falkland Islands, reaching 6.5 cm/year (which means 1.82 m for the 28 years studied). Furthermore, the complete reanalysis period (1948–2008) is analyzed in order to compare results with the assimilation data period (1980–2008), resulting in some discrepancies, especially in the Atlantic basin.     

Analysis of sedimentary processes on the Las Canteras beach (Las Palmas, Spain) for its planning and management

The sedimentary dynamics of a sandy beach located on the North coast of the Island of Gran Canaria has been studied in relation to physical processes.

The morphodynamic behaviour of the beach has been established and interpreted. Special emphasis has been placed on the characterization of erosive and accretionary processes by means of sediment transport calculations. Two sedimentary indices have been used to define these processes qualitatively and quantitatively. These indices are of importance for management.     

Fog measurements at the site “Falda Verde” north of Chañaral compared with other fog stations of Chile

Fog collection data registered through a Standard Fog Collector (SFC) installed by a local fishermen's association at a height of 600 m at the “Falda Verde” site, north of the Chilean harbor Chañaral (26°17′S/70°36′W), from November 1998 to November 2000, are analyzed. Trying to give new lights on the dynamics of fog along the Chilean northern coast, this article compares, for the first time, the data obtained at Falda Verde with those obtained at five other Chilean fog stations. The total time period runs from 1987 to 2001. A mean of 1.46 l/m²/day was registered at the Falda Verde site after 2 years of measurements, one of the lowest yields along the north Chilean coast. After a brief historical recapitulation of fog researches in the study area, geographical explanations of the water yields obtained in different sites are discussed. The annual mean collection from Cerro Moreno and Paposo shows a clearly different behavior from all other sites, showing a greater stability throughout the year. Other stations have a marked difference between extreme seasons. Alto Patache yields, if not the best in Chile, are very high and offer unexpected possibilities for future applications in the coast. Stations located away from the seashore (Cerro Guatalaya) are clearly less productive. Ocean proximity, altitude, south and southwest orientations of the coastal ranges and local relief explain some of the differences noted.     

The origin of the Sierra de Aracena Hollows in the Sierra Morena, Huelva, Andalucia, Spain

Hollows in the Sierra de Aracena, part of western sector of Sierra Morena region (Huelva, Spain), are geoecologically unusual macroforms. They are underlain by deeply weathered bedrock but have eutrophic soils with distinctive vegetation. Paleosols with very dark colours, a predominance of smectites and large amounts of total and free iron occur on the floors on the hollows. An evolutionary model is proposed for the hollows, involving differential weathering during the Mesozoic on plutonic and amphibolitic rocks, alpine tectonic activity followed by Quaternary erosion and exhumation leading to formation of erosional terraces.     

A method for finding the optimal predictor indices for local wave climate conditions

In this study, a method to obtain local wave predictor indices that take into account the wave generation process is described and applied to several locations. The method is based on a statistical model that relates significant wave height with an atmospheric predictor, defined by sea level pressure fields. The predictor is composed of a local and a regional part, representing the sea and the swell wave components, respectively. The spatial domain of the predictor is determined using the Evaluation of Source and Travel-time of wave Energy reaching a Local Area (ESTELA) method. The regional component of the predictor includes the recent historical atmospheric conditions responsible for the swell wave component at the target point. The regional predictor component has a historical temporal coverage (n-days) different to the local predictor component (daily coverage). Principal component analysis is applied to the daily predictor in order to detect the dominant variability patterns and their temporal coefficients. Multivariate regression model, fitted at daily scale for different n-days of the regional predictor, determines the optimum historical coverage. The monthly wave predictor indices are selected applying a regression model using the monthly values of the principal components of the daily predictor, with the optimum temporal coverage for the regional predictor. The daily predictor can be used in wave climate projections, while the monthly predictor can help to understand wave climate variability or long-term coastal morphodynamic anomalies.     

Moment and Bayesian wavelet regression from spatially correlated functional data

A new wavelet-based estimation methodology, in the context of spatial functional regression, is proposed to discriminate between small-scale and large scale variability of spatially correlated functional data, defined by depth-dependent curves. Specifically, the discrete wavelet transform of the data is computed in space and depth to reduce dimensionality. Moment-based regression estimation is applied for the approximation of the scaling coefficients of the functional response. While its wavelet coefficients are estimated in a Bayesian regression framework. Both regression approaches are implemented from the empirical versions of the scaling and wavelet auto-covariance and cross-covariance operators, characterizing the correlation structure of the spatial functional response. Weather stations in ocean islands display high spatial concentration. The proposed estimation methodology overcomes the difficulties arising in the estimation of ocean temperature field at different depths, from long records of ocean temperature measurements in these stations. Data are collected from The World-Wide Ocean Optics Database. The performance of the presented approach is tested in terms of 10-fold cross-validation, and residual spatial and depth correlation analysis. Additionally, an application to soil sciences, for prediction of electrical conductivity profiles is also considered to compare this approach with previous related ones, in the statistical analysis of spatially correlated curves in depth.