Search results for "rock"
showing 10 items of 1160 documents
La Rocca di Cefalù: modello geomeccanico e condizioni di rischio per la cittadina normanna
2021
La cittadina di Cefalù, ubicata a circa 70 km da Palermo, è una delle perle del Mediterraneo, per la bellezza dei luoghi, dominati dalla Rocca, imponente rupe carbonatica alta circa 250 m s.l.m., e per i beni architettonici (Figg. 1 e 2). Fondata dai greci con il nome di Κεφαλοίδιον tra il XIV e il XIII a.C., conserva sulla Rocca il palazzo santuario ciclopico-megalitico, noto come Tempio di Diana. Sul ciglio della Rocca e per il suo intero sviluppo si snoda la cinta muraria di tipo megalitico risalente alla fine del V secolo a.C. (periodo pre-ellenico), in parte ricostruita nel periodo bizantino (VII÷IX secolo d.C.). Nel periodo normanno (secolo XII d.C.) furono costruiti i principali monu…
INFLUENZA DEL FABRIC E DEL BONDING SULLO STATO CRITICO E SULLO SNERVAMENTO DELLE CALCARENITI
2011
The research has been devoted to the theoretical interpretation and to the modeling of the mechanical behavior of Quaternary structured soils in the Western South-Western Sicily belonging to the complex calcarenitic-sandy-clayey. After a review about the state of knowledge on the influence of textural characteristics such as fabric and bonding on mechanical behavior, this note presents the results of an experimental analysis by mean of textural identification tests, oedometer tests, triaxial and isotropic tests. For each lithotype critical state conditions and yield strength are defined.
Influence of the behaviour of soft rocks on cliff evolution
2010
Two cases, of evolution of mor phostructure of cliffs in soft rocks like tuff and calcarenite, respectively outcropping in the Cape of Posillipo in Campania and in the Agrigento town and Valley of Tem- ples in Sicily, are analyzed on the basis of mor phologic characteristics of the sites, mesostructural survey and mechanical characterisation of the lithotypes. The cultural and environmental heritage of these sites is heavily hastened by instability processes, due to the super position of different lithotypes, the presence of dis- continuities and differential erosion and deformation of bedrock. Both the rock masses are characterized by variability of the cohesion and the cementation, and we…
Propellant non-steady burning effects on controllable solid rocket motor internal ballistics
2009
An analysis of the unsteady non-linear behavior of the controllable solid propellant rocket motor (CSRM) consequent to rapid and relevant nozzle operation is presented. The study includes a development of a non-linear unsteady combustion model able to handle relevant and rapid chamber pressure changes typical of CSRMs. The CSRM nonlinear unsteady model is implemented according to a main solver - sub models architecture and uses different time scales. The formulation of the combustion gas mass flow rate is developed considering the propellant density, the unsteady combustion, the regression of the combustion surface and the outflow through the variable nozzle. The grain surface involved in t…
Early pastoral communities in the mountains of Sicily. Prehistoric evidence from Vallone Inferno (Scillato) in the palaeoenvironmental framework of t…
2021
Abstract This paper discusses the Middle Neolithic and the Early Bronze Age phases of the occupation of a rock shelter at Vallone Inferno (Scillato, Palermo) in Sicily. Vallone Inferno is a key site for studying the early establishment and development of pastoralism in the prehistoric mountainous environments of Sicily. Seasonal use of the site as a shelter is documented for the earliest pastoral communities that exploited the Madonie mountain range. The results of the analysis of pottery and lithic assemblages contribute to the definition of two chronocultural frameworks that were linked by the same economic subsistence base. The special role of obsidian emerges, while the mobility pattern…
Within the symbolic world of the prehistoric hunters: A GIS-based and 3D model analysis of sites with complexes of linear incisions in western Sicily
2021
Abstract The prehistoric peopling of Sicily has left scattered traces of symbolic activities through well-known rock art expressions in caves and rock shelters located all around the island (among the most significant, the sites of Addaura, Racchio and Genovese). A peculiar phenomenon is the incision of linear signs, often grouped on the same rocky walls, hidden in fissures or placed at the entrance of the underground chambers of caves. In this report, we investigate a sample of these graphic expressions from a spatial and technical point of view. A GIS-based approach presents the territorial pattern providing insight, on a macroscale, into the intentional positioning of the sign complexes.…
Cultura pop nelle brecce del silenzio
2009
Prendendo spunto dal volume di Alex Ross "Il resto è rumore. Ascoltando il XX secolo" (Bompiani 2009), l'articolo esplora le linea d'ombra che separa/unisce i mondi della musica colta e del rock: dalla musica concreta ai Pink Floyd e al minimalismo, e viceversa.
Corpi che contano. Prolegomeni per una teoria della materialità delle immagini
2022
Oggetto di questo saggio è un tipo di artefatti che ha avu- to in passato, ha ancora e avrà in futuro un significato centra- le nella produzione dell’Homo Sapiens: le miniature. Si tratta di oggetti che hanno accompagnato tutta la sua evoluzione e la cui datazione non ha smesso di sorprendere i paleontologi. Sappiamo, ad esempio, che la scultura antropomorfa ritro- vata a Berekhat Ram (fig. 1) in Israele e quella di Tan Tan (fig. 2) in Marocco risalgono a parecchie centinaia di migliaia di anni fa, e dunque sono ben più antiche delle cosiddette Veneri che popolano il Paleolitico superiore europeo. The subject of this essay is a type of artifact that has had in the past, still has and will h…
Contrasting metamorphic evolution of metasedimentary rocks from the Çine and Selimiye nappes in the Anatolide belt, western Turkey
2003
P-T conditions, mineral isograds, the relation of the latter to foliation planes and kinematic indicators are used to elucidate the tectonic nature and evolution of a shear zone in an orogen exhumed from mid- crustal depths in western Turkey. Furthermore, we discuss whether simple monometamorphic fabrics of rock units from different nappes result from one single orogeny or are related to different orogenies. Metasedimentary rocks from the Cine and Selimiye nappes at the southern rim of the Anatolide belt of western Turkey record different metamorphic evolutions. The Eocene Selimiye shear zone separates both nappes. Metasedimentary rocks from the Cine nappe underneath the Selimiye shear zone…
1999
Two retrograde, amphibolite facies shear zones were studied to explore the relationship between retrograde mineral reactions, volume strain, fluid flow, mylonitization, and coaxial versus noncoaxial deformation. The two shear zones are the contractional Mafwewu Hills shear zone and the transcurrently displacing Mkamasa River shear zone of northern Malawi. In general, shear-zone formation is characterized by the breakdown of feldspar and biotite and the formation of sillimanite, quartz, and water. Silica, alkali, and alkali earth elements were mobile. Mass-balance calculations, based on major- and trace-element geochemistry, indicate as much as 50%–60% volume loss in mylonite. Fluid to rock …