Geochemistry

The felsic lavas of the Bamenda Mountains, in the main part of the Cameroon Volcanic Line, are mainly represented by trachytes, with subordinated benmoreites and alkaline to peralkaline rhyolites. New K–Ar geochronological data define two main volcanic episodes, the first one between 18 and 22Ma, and the second one from 12.5 to 13.5Ma. Geochemical data indicate that these felsic rocks

Deposits from the Minoan Santorini (Thera) eruption in the eastern Mediterranean region constitute the most important regional stratigraphic marker in the chronological perplexity of the 2nd millennium BCE. Extensive tsunami depos- its were discovered in Crete at the Minoan archaeological site of Palaikastro, containing reworked volcanic Santorini ash. Hence, airborne deposition of volcanic ash, probably during the 1st (Plinian) eruption phase, preceded the tsunami, which was apparently generated during the 3rd or 4th phase of the eruption, based on evidence from Thera. Average radiocarbon dates (uncalibrated) of animal bones in the Palaikastro tsunami deposits along the coast (3350 ± 25 BP) and at the inland archaeo- logical site (3352 ± 23 BP) are astoundingly similar to the average 14C date for the Minoan Santorini eruption at Akrotiri on Thera (3350 ± 10 BP). The wiggle-matched 14C date of the eruption in calendar years is 1627-1600 cal BCE. Late Minoan IA pottery is the younges...

In 1962, what was then a landmark novel ‘Silent Spring’ was published, the author was Rachel Carson. The novel highlighted the effects of man made chemicals on the environment and ecosystems. Carson describes in this novel, the powerful and detrimental effects that humans have on the natural world
This report will describe the harmful effects of environmental chemicals on man and ecosystems and attempts to assess whether these effects have lessened since the publication of Rachel Carson’s ‘Silent Spring’. Scientific evidence will be presented of the changing effects of environmental chemicals through time and on a global scale. Their methods of toxicity will be described

ABSTRACT We investigated the casting cores of twelve large bronze masterpieces of the Florentine Renaissance and Mannerism (artworks by Ghiberti, Donatello, Verrocchio, Rustici, and Danti). Materials were characterized in their mineralogical-petrographic features, chemical composition, organic content and fossil traces. The results achieved provide information on the main recipes employed for manufacturing the casting cores, which largely agree with written sources of the time, and shed light on the art foundry processes between the 15th–16th centuries. The data collected point out a pronounced affinity of natural raw materials used in all the casting cores investigated, consisting in silty-sandy clays with a suitable natural fine-grained temper component. A large use of organic fibres and matters of both animal and vegetal origin and a minor use of gypsum in selected workshops (Rustici, Verrocchio) were highlighted. Textural analyses allowed gaining information on direct vs indirect methods of casting, while firing temperatures up to about 1000 °C were estimated from mineralogical and microstructural observations. Despite the strong similarities, significant differences among the various samples analysed were pointed out, providing some initial analytical clues that suggest different practices in separate workshops. Finally, the whole petrographic, geochemical and paleontological data gave information on the provenance of the clayey raw materials. This work represents the first step of a systematic approach to the classification of the core materials used in Florentine foundries along the centuries and shows the significant contribution the petrographic analyses can provide to the interpretation of the execution processes of large bronzes.

Twenty years of continuous Earth observation by satellite SAR have resulted in numerous new insights into active volcanism, including a better understanding of subsurface magma storage and transport, deposition of volcanic materials on the surface, and the structure and development of volcanic edifices. This massive archive of data has resulted in fundamental leaps in our understanding of how volcanoes work - for example, identifying magma accumulation at supposedly quiescent volcanoes, even in remote areas or in the absence of ground-based data. In addition, global compilations of volcanic activity facilitate comparison of deformation behavior between different volcanic arcs and statistical evaluation of the strong link between deformation and eruption. SAR data are also increasingly used in timely hazard evaluation thanks to decreases in data latency and growth in processing and analysis techniques. The existing archive of SAR imagery is on the cusp of being enhanced by a new gene...