The seasonal cycle is a fundamental aspect of climate, with a significant influence on mean climate and on human societies. Assessing seasonality in different climate states is therefore important but, outside the tropics, very few palaeoclimate records with seasonal resolution exist and there are currently no glacial-age seasonal-resolution sea-surface-temperature (SST) records at mid to high latitudes. Here we show that both Mg/Ca and oxygen isotope (δ18O) ratios in modern limpet (Patella) shells record the seasonal range of SST in the western Mediterranean - a region particularly susceptible to seasonal change. Analysis of a suite of fossil limpet shells from Gibraltar shows that SST seasonality was greater during the last glacial by ~2°C as a result of greater winter cooling. These extra-tropical seasonal-resolution SST records for the last glacial suggest that the presence of large ice-sheets in the northern hemisphere enhances winter cooling. This result also indicates that seasonality in the Mediterranean is not well-represented in most palaeoclimate models, which typically show little change in seasonal amplitude, and provides a new test for the accuracy of climate models. © 2011 Elsevier B.V

Trinitite is the glass formed during the first atomic bomb test near Socorro, New Mexico, on July 16, 1945. The protolith for the glass is arkosic sand. The majority of the glass is bottle green in color, but a red variety is found in the northern quadrant of the test site. Glass beads and dumbbells, similar in morphology to micro-tektites, are also found at the Trinity site. The original description of this material, which appeared in American Mineralogist in 1948, noted the presence of two glasses with distinctly different indices of refraction (n = 1.46 and 1.51–1.54). Scanning electron microscopy (SEM) and Quantitative Evaluation of Minerals by SCANning electron microscopy (QEMSCAN) analysis is used to investigate the chemical composition and fine-scale structure of the glass. The glass is heterogeneous at the tens of micrometer scale with discrete layers of glass showing flow-like structures. The low index of refraction glass is essentially SiO₂ (high-Si glass), but the higher index of refraction glass (low-Si glass) shows a range of chemical compositions. Embedded in the glass are partially melted quartz (α-quartz as determined by X-ray diffraction) and feldspar grains. The red trinitite consists of the same two glass components along with additional Cu-rich, Fe-rich, and Pb-rich silicate glasses. Metallic globules are common in the red trinitite In terms of viscosity, the high-Si and low-Si glasses differ by several orders of magnitude, and there is minimal mixing between the two glasses. QEMSCAN analysis reveals that there are several chemical subgroups (that can be characterized as simple mixtures of melted mineral components) within the low-Si glasses, and there is limited mixing between these glass subgroups. The red trinitite contains regions of Fe-rich glass, which show sharp contact with surrounding Fe-poor glass. Both the textural and chemical data suggest that these two glasses existed as immiscible liquids. The metallic droplets in the red trinitite, which consist of variable amounts of Cu, Pb, and Fe, show textural evidence of unmixing. These metals are largely derived from anthropogenic sources—Cu wire, Pb bricks, and the steel tower and bomb casing. The combination of mineralogical and chemical data indicate that temperatures on the order of 1600 °C and pressures of at least 8 GPa were reached during the atomic detonation and that there was a reducing environment during cooling, as evidenced by the presence of native metals, metal sulfides, and a low-Fe³⁺/Fe²⁺ ratio. Independent estimates of maximum temperature during the detonation are on the order of 8000 K, far higher than suggested by the mineral data. This discrepancy is probably due to the very short duration of the event. In all respects, the trinitite glasses are similar to tektites and fulgurites, and by analogy one conclusion is that temperature estimates based on mineralogical observations for these materials also underestimate the maximum temperatures.

New evidence from the SW Northern Highlands of Scotland establishes the southerly extension of the Sgurr Beag Slide. Interpretation of changes in the mineralogy of calcsilicate rocks, particularly the use of the anorthite content of plagioclase feldspar as an index of metamorphic grade, together with consideration of the texture and mineralogy of pelitic rocks, suggests that the slide juxtaposes crustal segments of different metamorphic grade and history.Movement on the slide post-dates a major phase of regional metamorphism and two phases of regional deformation of Precambrian age, was synchronous with a regional fold-forming event and regional metamorphism at or before c. 467 Ma (Caledonian), and was followed by regional folding. Models of the thermal effects of displacement across syn-metamorphic shear zones are investigated with particular reference to the roles of thermal relaxation and levels of shear strain. A model based on the development of a ductile, syn-metamorphic, asymmetric shear zone best explains the metamorphic patterns associated with the Sgurr Beag Slide. An original low to moderate easterly dip is implied, with north-westerly upthrusting of the eastern crustal block.