Study of Johnsons Glacier (Livingston Island, Antarctica) by means of shallow ice cores and their tephra and by analysis of 137Cs content

With the aim of monitoring the dynamics of the Livingston Island ice cap, the Departament de Geodinàmica i Geofísica of the Universitat de Barcelona began ye a r ly surveys in the austral summer of 1994-95 on Johnsons Glacier. During this field campaign 10 shallow ice cores were sampled with a manual ve rtical ice-core drilling machine. The objectives were: i) to detect the tephra layer accumulated on the glacier surface, attributed to the 1970 Deception Island pyroclastic eruption, today interstratified; ii) to verify wheter this layer might serve as a reference level; iii) to measure the 1 3 7Cs radio-isotope concentration accumulated in the 1965 snow stratum; iv) to use the isochrone layer as a mean of verifying the age of the 1970 tephra layer; and, v) to calculate both the equilibrium line of the glacier and average mass balance over the last 28 years (1965-1993). The stratigr a p hy of the cores, their cumulative density curves and the isothermal ice temperatures recorded confi rm that Johnsons Glacier is a temperate glacier. Wi n d, solar radiation heating and liquid water are the main agents controlling the ve rtical and horizontal redistribution of the volcanic and cryoclastic particles that are sedimented and remain interstratified within the g l a c i e r. It is because of this redistribution that the 1970 tephra layer does not always serve as a ve ry good reference level. The position of the equilibrium line altitude (ELA) in 1993, obtained by the 1 3 7Cs spectrometric analysis, varies from about 200 m a.s.l. to 250 m a.s.l. This indicates a rising trend in the equilibrium line altitude from the beginning of the 1970s to the present day. The va rying slope orientation of Johnsons Glacier relative to the prevailing NE wind gives rise to large local differences in snow accumulation, which locally modifies the equilibrium line altitude. In the cores studied, 1 3 7Cs appears to be associated with the 1970 tephra laye r. This indicates an intense ablation episode throughout the sampled area (at least up to 330 m a.s.l), which probably occurred synchronically to the 1970 tephra deposition or later. A rough estimate of the specific mass balance reveals a considerable accumulation gradient related to the increase with altitude.

Addenda a la biografia i l'obra del pintor Joan Arnau Moret (1603-1693)

The present article treats of the painter Joan Arnau Moret, catalan painter of the 17th century. Aspects treat each other as the order of the great picture preserved in the cathedral of Barcelona with the iconography The de live ry o f the ke ys of the city of Barcelona to the Immaculate, the biographical news it extracted of the process of canonization of santa Maria of Cervelló or the professional relation that Joan Arnau joined with the prince Joan Josep d’Àustria newly finished the Segadors war (The Reapers’ War). Of them the study also announces a work – the Saint Cathe rine o f Ale xandria of the chapel of Saint Catherine of the cathedral of Girona – proposes to attribute four paintings more – the paintings of the altarpiece of The Saints fo ur Martyrs of the cathedral of Girona – and thinks about the controversial paintings of the altarpiece of the Castle of Vilassar and of the monastery of Sant Joan of the Abadesses. Finally, by means of the stylistic reading of the new works, which the author considers of the best of his catalogue, one tries to demonstrate that thesources of your figurative culture and stylistic are in the painting of Madrid of the first decades of the 17th century