Abundance of diatoms and foraminifers in the surface sediment layer of the southeastern Laptev Sea shelf

The study of diatoms and benthic foraminifers from the southeastern shelf of the Laptev Sea shows that their most diverse and abundant recent assemblages populate the peripheral underwater part of the Lena River delta representing the marginal filter of the sea. This area is characterized by intense interaction between fresh waters of Siberian rivers and basin seawater, Atlantic one included. Local Late Holocene (~last 2300 years) environments reflect the main regional and global paleoclimatic changes, the Medieval Warm Period (~600-1100 years B.P.) and the Little Ice Age (~100-600 years B.P.) inclusive. In addition, composition and distribution of planktonic foraminifers implies strong influence of Atlantic water during the Holocene optimum ~5100-6200 years B.P.

Lithology and pollen record of 4 profiles from the Bavaria, southern Germany

Palynological investigations of sediments from northern Bavaria (Rhön, Grabfeld, Lange Berge) reveal the Late Glacial and Postglacial history of the regional vegetation. The older sedirnents were found in the Rhön (Schwarzes Moor) and date back into the Bölling Period. At the end of that period pine spread into the Grabfeld. In both areas Lacher Tuff has been found. A radiocarbon date of 10,300 BP was found for the Late Glacial - Postglacial transition and one of 9300 BP for the Preboreal - Boreal transition. Hazel reached its highest values in the Rhön around 7,400 BP. During the Atlanticum a deciduous mixed oak forest covered the Rhön and Grabfeld regions. Beech dominated since the Subatlanticum. In the Lange Berge region, however, a mixed forest with Fagus, Picea, Pinus and Abies developed. In the Rhön first anthropogenic influence was found during the Latene Period. The boundary between zone IX and X has been dated at 820 A.D., and the start of extensive forest clearances at 1000 A. D. A culmination of landuse was found for the Medieval Period. At the end of that period however the Rhön was deserted. New forest clearances started around 1500 A.D., but were interrupted by the 'Thirty Years War'. Afterwards the Rhön got its present appearance.

Accumulation rate and stable oxygen isotope ratios of the ice cores from the North Greenland Traverse

We present for the first time all 12 d18O records obtained from ice cores drilled in the framework of the North Greenland Traverse (NGT) between 1993 and 1995 in northern Greenland. The cores cover an area of 680 km × 317 km, 10 % of the Greenland ice sheet. Depending on core length (100-175 m) and accumulation rate (90-200 kg/m**2/a) the single records reflect an isotope-temperature history over the last 500-1100 years. Lowest d18O mean values occur north of the summit and east of the main divide as a consequence of Greenland's topography. In general, ice cores drilled on the main ice divide show different results than those drilled east of the main ice divide that might be influenced by secondary regional moisture sources. A stack of all NGT records and the NGRIP record is presented with improved signal-to-noise ratio. Compared to single records, this stack represents the mean d18O signal for northern Greenland that is interpreted as proxy for temperature. Our northern Greenland d18O stack indicates distinctly enriched d18O values during medieval times, about AD 1420 ± 20 and from AD 1870 onwards. The period between AD 1420 and AD 1850 has depleted d18O values compared to the average for the entire millennium and represents the Little Ice Age. The d18O values of the 20th century are comparable to the medieval period but are lower than that about AD 1420.

Ethics and materials. Some Spanish Case Studies

In Navea, north of Spain, a medieval arch bridge shows a visible distortion (fig.1a). A stone falls down from the web of a gothic vault in a big parish church in Burgos (fig. 1b), and a voussoir falls down from the rib of another gothic vault in Oviedo (fig. 1c). An oval dome collapses in Zaragoza, though another four identical domes remain safe (fig. 1d). Sometimes the building has to support new, heavier loads. The ruin of the abandoned (since the 19th Century) monastery of Melón should be consolidated, some vaults are rebuilt and the visitors can walk over them. A Franciscan Convent is going to be turned into a Cultural Centre, the loads to be supported being multiplied by a factor of two. A little medieval bridge is asked to support the pass of heavy lorries. These are some of the cases I have studied in the last two decades, all of them referring to questions of structural safety. These are the kind of situations which often occurs in the field of Historic Structures. They require a study and an answer. This is no scholarly work (though in some cases new lines of future research will emerge). A judgement must be made by the expert and this judgement affects the safety and economy, in the last instance, of people. As there are rarely unique answers, the behaviour of the expert, then, can also be judged as "ethical", if he proposes an intervention that is necessary and adequate (or, recommends no intervention, judging the situation safe), or "non-ethical", if recommends an unnecessary or disproportionate intervention. In relation to the monument, also, the proposal can be judged ethically; any intervention damaging seriously the character of the monument may be labelled un-ethical.

Hacia una taxonomía constructiva de las tapias de tierra y fábricas encofradas históricas = Towards a constructive taxonomy of the historical rammed-earth and formwork masonry

El objetivo fundamental de la investigación es el estudio de los fundamentos constructivos de las fábricas históricas de tapia de tierra y mampostería encofrada de las fortificaciones bajomedievales. Ante las incertidumbres detectadas en la datación de estas estructuras y frente al excesivo número de excepciones que quedan fuera de las clasificaciones tradicionalmente empleadas para estudiar este tipo de técnicas, el artículo desarrolla una propuesta de tipología o taxonomía constructiva basada en un sistema abierto. Este sistema nace del análisis de un número significativo de fábricas y atiende a diversos parámetros de control para la completa caracterización de cada fábrica: material, grado de compactación, función constructiva, encofrado, acabado superficial, combinación de materiales y situación, profundidad, formación y sección de los agujales. Cada fábrica se clasifica mediante una etiqueta alfanumérica. El sistema permite establecer tipos constructivos con los que se genera una clasificación cronotipológica constructiva. ABSTRACT The principal aim of the research is the study of the constructive reasons of the historical masonries built with rammed earth and formwork masonry, belonging to late medieval fortifications. Uncertainties have been warned about dating the historical masonries and there are excessive exceptions that do not fall in the rankings traditionally employed to study these techniques. Due to these reasons, the article develops a proposal of constructive typology or taxonomy based in an open system that comes from the analysis of a representative number of masonries and that attends to several control parameters tor the complete characterization of each masonry: material, compaction degree, constructive function, formwork, rendering, combination of materials and, last, the situation, deepness, formation and section of the putlogholes. Each masonry is classified through an alphanumeric label. The system allows establishing several constructive types which it is possible to do a cronotypological and constructive classification.