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The existence of marine ice transfer along the underside of the Hell's Gate Ice Shelf ( Victoria Land), is indicated by an isotopic and chemical study of ice cores. Because of top surface ablation, the marine ice formed at the ice shelf‐ocean interface, ultimately appears at shelf surface. A succession of congelation, platelet and frazil ice is shown to occur. The combined study of stable isotope composition and of the sodium content of these different ice types proves to be a valuable tool for specifying the ice shelf‐ocean interactions in this area. Two different freezing zones separated by a melting rone exist; the parent water for the frazil ice is meltwater from congelation ice which appears in the upstream zone.

Laboratory investigations have been carried out on one‐ and two‐component artificial sand samples in order to estimate the relations between formation factor (F), porosity (φ), and permeability (K). The measurements were carried out by varying grain size and size distribution while keeping constant shape and packing; in our experimental conditions the measured formation factor approximated the intrinsic formation factor. The relationship between formation factor and porosity (F = a ·φ−m) is independent of grain size and size distribution; the coefficient values are: a = 1·15, m = 1·42. The relationship between permeability and formation factor has the general form K = r · F−s, where s is constant, and r is a function of the mean size d of the small component of the samples. The K‐F relation can be established only if d is constant; in these conditions the relationship is an inverse one, and the negative trend is related to the variations in size distribution.

ZusammenfassungAcht neue seismische Refraktionsprofile in den Nordappenninen und den Ligurischen Alpen wurden berechnet, und zwar in der Fortsetzung von Reflexionsprofilen im Pobecken, die von Bohrungen kontrolliert sind. Diese neuen Refraktionsprofile tragen bei zu einer besseren Erfassung der Untergrundstruktur dieses verwickelten ,,Ligurischen Knotens". Im besonderen haben sie die Abgrenzung von einigen K6rpern hoher Geschwindigkeit erm6glicht, die korrelierbar sind mit gewissen geologischen Einheiten, nfimlich mit dem adriatischen Mesozoikum, den Ophiolithen der appenninischen Liguriden sowie mit den Antolaflysch unterlagernden Ophiolithen und Karbonaten der ligurischen Alpen. Bei der Verbindung der Reflexions-und Refraktionslinien stellt sich heraus, dab die genannten Einheiten hoher Geschwindigkeit durch wichtige Dislokationen getrennt sind: die basale Uberschiebung der Padaniden (PlioPleistocaen), die Villalvernia-Varzi-Linie (OligoMiocaen), die Ottone-Levanto-Linie (Oligo-Miocaen) und den Volpedo-Valle Salimbene-Bruch (Oligo-Miocaen, reaktiviert als Transferbruch im PlioPleistocaen). Die 3D-Geometrie des Ligurischen Knotens ist interpretierbar im Rahmen der regionalen Kinematik. Sie ist vertr~glich mit einem Modell, das eine oligocaen-frfihmiocaene NW-Translation des Adria-Indenters vorsieht, gekoppelt mit einem Einbruch des proven9alisch-ligurischen Beckens und einer Rotation des sardo-ligurischen Komplexes in die nach Osten zurfickweichende adriatische Subduktionszone. Die refraktionsseismischen Berechnungen erstrecken sich nur bis zu einer Tiefe von 15 km; sie werden jedoch erg/inzt durch Daten fiber die Lage der Moho, die ftir die Europ/iische Geotraverse (EGT) erarbeitet wurden. Die Moho scheint in eine Anzahl von Dom/inen zerlegt zu sein, die interpretiert werden k6nnen im Lichte der Zusammensetzung und tektonischen Geschichte der h6heren Krustenteile. Insbesondere scheint die tiefstgelegene Moho-Dom/ine abgeschnitten zu werden durch den Volpedo-Valle Salimbene-Bruch, welcher folglich die ganze Kruste in Mitleidenschaft ziehen wtirde. Abstract

A method for solving the inverse problem in hydrogeology is presented. This method is suitable for computing the interblock transmissivities (harmonic mean or others) referred to the sides of the network blocks of a nonhomogeneous, anisotropic aquifer in steady state flow. The interblock transmissivities computing procedure is based on the comparison between real gradients and the ones generated by a 'comparison model' whose initial transmissivity value is arbitrarily chosen and constant through out the surveyed area. Alternative solutions of interblock transmissivities, one for each constant initial transmissivity value utilized in the comparison model, are obtained. Generally, these solutions differ from each other, but all of them present the characteristics of being able to reproduce, with the precision of an arbitrarily small e, the real piezometric heads, respecting the geometry and the boundary conditions of the real aquifer. The selection of the value, or set of values, of the initial transmissivity to put into the comparison model in order to obtain one solution of computed interblock transmissivities close to the real ones, both as trends and as absolute values, is rather critical. The minimum head anomaly criterion and the bottleneck criterion enable one to select a value or a set of values of initial transmissivity. These criteria exploit only the data needed for the solution of the inverse problem (real piezometric heads, geometry, and boundary conditions), and they lead to a suitable initial transmissivity that, put into the comparison model, allow one to obtain a good and meaningful solution of computed interblock transmissivities. The comparison model method and the two aforementioned criteria have been applied to a numerical case study bearing good results. The method has been tested, in order to evaluate its effectiveness, even in the case of noisy piezometric heads (piezometric heads with random errors). Even in this case the method bore satisfactory and useful results. Finally, a promising approach to the inverse problem solution, when one has at his disposal at least four sets of data coming from as many hydraulic situations, has been briefly described. objective function composed of some measure of the difference between observed and computed heads. Among the authors who affronted the identification problem, we will mention Emsellem and DeMarsily [1971], Neuman [1973], Neuman et al. [1980], Frind and Pinder [1973], Hefez et al. [1975], Sagar et al. [1975], Neuman and Yakowitz [1979], and Irmay [1980]. Scarascia and Ponzini [1972] presented a method for the solution of the inverse problem that minimizes the anomalies between the measured piezometric heads and the computed ones. The present paper, which from some aspects is a continuation of the Scarascia and Ponzini [!972] paper, describes a method suitable for the identification of the transmissivities of a single-layer aquifer in steady state flow, in which the boundary conditions (piezometric heads at the boundaries or known flow rates, fl...

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Geophysical investigations were undertaken in the Livigno area (Sondrio, northern Italy) during 1991–92 at a number of sites where permafrost had been suggested through the application of other techniques, such as geomorphological studies, measurements of bottom temperature of winter snow cover (BTS), measurement of ground temperature in summertime (STG), and temperature of spring waters. Geoelectrical surveys confirm and characterize these permafrost occurrences. Furthermore, they indicate that, outside the rock glaciers, permafrost is also present in some gelifluction lobes. The permafrost bodies differ with regard to parameters such as resistivity, depth and thickness. Resistivity ranges from 18,000 to 560,000 ωm (ohm metres), depth varies between 8 and 21.1 m, and the active layer is 2 to 4.7 m thick in those bodies that can be considered active on the basis of morphological features.

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