3,131 research outputs found
La Geologia regional, clau de volta del mètode geològic
Des dels inicis de la geologia moderna, el mètode de treball impulsat per l'escola
werneriana dóna un paper fonamental a la geologia regional, tant pel que fa a la geologia històrica corn a la geologia causal o dels processos. El desenvolupament de la geologia regional porta al mapa geològic, des d'aleshores l'eina més estesa per comunicar, de manera sintètica, les informacions fenomenològiques de
caràcter regional. La geologia regional té avui una important presència en els diferents camps de la geologia i ocupa una posició clau en el mètode geològic, atès el caràcter essencialment històric i regional de la geologia. Constitueix un primer grau interpretatiu que es pot interpretar en termes de geologia històrica, explicar en termes de geologia causal o utilitzar-lo en la producció de teoria causal, amb la qual, en la progressió del pensament geològic manté una necessària relació iterativa.Since the early stages of modern geology, the
method developed by geologists of the wernerian
school has given a fundamental role to regional
geology in relation to both, historical geology and
causal or process geology. The development of
regional geology led to geological maps, since
then the most extended tool to sinthetically
communicate phenomenological informations
of regional nature. Nowadays, regional geology
is largely present in the different fields of geology,
and is a keystone of the geological method
because of the essentially historical and regional
nature of geology. It constitutes a first step in
geological interpretation which can be interpreted
in terms of historical geology, explained in terms
of causal geology, or be used in the production
of causal theory, with which it maintains a
necessary iterative relationship in the advance
of the geological thought.Desde los inicios de la geología moderna, el método de trabajo impulsado por la escuela
werneriana otorga un papel fundamental a la geología regional, tanto en relación a la geología histórica como a la geología causal o de los procesos. El desarrollo de la geología regional conduce al mapa geológico, desde entonces la herramienta más extendida para comunicar, de manera sintética, las informaciones fenomenológicas de carácter regional. La geología regional tiene hoy en día una importante presencia en los distintos campos de la geología y ocupa una posición clave en el
método geológico dado el carácter esencialmente histórico y regional de la geología. Constituye un primer escalón interpretativo que puede, a su vez, interpretarse en términos de geología histórica, explicarse en términos de geología
causal o utilizarlo en la producción de teoría causal, con la que, en el progreso del pensamiento geológico, mantiene una necesaria relación iterativa
Development of geology in Spain : a case study of a marginal science
Geology in Spain developed outside the mainstream of major geological ideas. Geology was introduced intothe country when it had already grown mature. The history of geology in Spain is series of initiatives aimedat aligning the country with the innovative currents taking place in the rest of Europe. This was accomplishedby different protagonists: state and private institutions during the Enlightenment, mining engineers in the 19thcentury, church and regional authorities in Catalonia in the last quarter of the 19th century and in the early years ofthe 20th century, and the university in the 20th century. The importance of the links with foreign geologists shouldnot be underestimated. Not until the 20th century did improvement in living standards and university expansionallow Spanish geology to attain the critical number of scientists needed to undertake quality research and achievefull integration into the international community
Dark Energy Survey year 1 results: Galaxy-galaxy lensing
We present galaxy-galaxy lensing measurements from 1321 sq. deg. of the Dark Energy Survey (DES) Year 1 (Y1) data. The lens sample consists of a selection of 660,000 red galaxies with high-precision photometric redshifts, known as redMaGiC, split into five tomographic bins in the redshift range 0.15 < z < 0.9. We use two different source samples, obtained from the Metacalibration (26 million galaxies) and im3shape (18 million galaxies) shear estimation codes, which are split into four photometric redshift bins in the range 0.2 < z < 1.3. We perform extensive testing of potential systematic effects that can bias the galaxy-galaxy lensing signal, including those from shear estimation, photometric redshifts, and observational properties. Covariances are obtained from jackknife subsamples of the data and validated with a suite of log-normal simulations. We use the shear-ratio geometric test to obtain independent constraints on the mean of the source redshift distributions, providing validation of those obtained from other photo-z studies with the same data. We find consistency between the galaxy bias estimates obtained from our galaxy-galaxy lensing measurements and from galaxy clustering, therefore showing the galaxy-matter cross-correlation coefficient r to be consistent with one, measured over the scales used for the cosmological analysis. The results in this work present one of the three two-point correlation functions, along with galaxy clustering and cosmic shear, used in the DES cosmological analysis of Y1 data, and hence the methodology and the systematics tests presented here provide a critical input for that study as well as for future cosmological analyses in DES and other photometric galaxy surveys
Estudio tectónico del Paleozoico inferior del Pirineo entre la Cerdaña y el río Ter (resumen)
El análisis estructural del domo del río Freser (Pirineos Orientales, España) permite poner de manifiesto una sucesión de tres fases de plegamiento hercinianas. Se describen las características de las mismas y se comparan con las descritas por otros autores en regiones vecinas
Precisiones acerca de la significación petrológica y estructural de las rocas gneísicas y cataclásticas del Maresme (prov. de Barcelona)
Se estudian pequeños afloramientos de rocas metamórficas y cataclásticas ubicadas en el granito herciniano de la Cadena Costera Catalana al NE de Barcelona. Tras una breve síntesis de las diversas ideas emitidas sobre la génesis de estas rocas se realiza un estudio comparativo de las mismas. De él se infiere la presencia de dos grupos de rocas de significación petrogenética y tectónica distinta: 1) Los gneises de Mataró, que resultan del metamorfismo polifásico progresivo herciniano de sedimentos del Paleozoico inferior y 2) las rocas cataelásticas de Caldetes, ligadas a deformaciones internas en el batolito del granito herciniano postectónico, acompañadas de transformaciones hidrotermales en mayor o menor grado.Small outcrops of metamorphic and cataclastic rocks, located in the Hercynian granite of the Catalan Litoral Ridge (NE from Barcelona) were studied. Following a brief examination of the previous ideas issued concerning the origin of these rocks, a comparative study has been made. As a result of the forementioned, the presence of two groups of rocks could be established, both having an individual petrogenetic and tectonic signification: 1) The Mataró Gneises outcome of a progressive and polyphasic metamorphism of Lower Paleozoic sedimentary rocks. 2) The Caldetes Cataclastic Rocks, are related to interna1 deformations within the hercynian late tectonic granite batholith, assisted in some extent by hydrothermalism
Developing a novel approach to analyse the regimes of temporary streams and their controls on aquatic biota
Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. The use of the aquatic fauna structural and functional characteristics to assess the ecological quality of a temporary stream reach can not therefore be made without taking into account the controls imposed by the hydrological regime. This paper develops some methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: flood, riffles, connected, pools, dry and arid. We used the water discharge records from gauging stations or simulations using rainfall-runoff models to infer the temporal patterns of occurrence of these states using the developed aquatic states frequency graph. The visual analysis of this graph is complemented by the development of two metrics based on the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of the aquatic regimes of temporary streams in terms of their influence over the development of aquatic life is put forward, defining Permanent, Temporary-pools, Temporary-dry and Episodic regime types. All these methods were tested with data from eight temporary streams around the Mediterranean from MIRAGE project and its application was a precondition to assess the ecological quality of these streams using the current methods prescribed in the European Water Framework Directive for macroinvertebrate communities
Sobre la compresión alpina en el sector central de las Cadenas Costeras Catalanas
Este trabajo tiene como finalidad el estudio de la compresión alpina en la cobertera mesozoica del sector central de las Cadenas Costeras Catalanas. A nivel microestructural se reconoce un giro de la dirección de compresión en el tiempo, de NW-SE -sincrónica del plegamiento de la cadena- a N-S y NE-W.Si una evolución similar es admitida a nivel del zócalo, puede explicarse la existencia, en los Catalánides, de fallas transversales levógiras. y dextrógiras. Finalmente se compara la evolución propuesta en el sector central de los Catalánides con la descrita por otros autores en la Cordillera Ibérica y los Pirineos, y se concluye que todo el ámbito NE del Bloque Ibérico ha sufrido una evolución homogénea de la compresión durante el Paleógeno
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