ALBERT

Description: SEDIMENTOLOGY AND GEOMORPHOLOGY OF EL BIERZO (NW SPAIN) The purpose of this investigation was to study sedimentation in an intramontane basin in its relation to the relief of the surrounding mountain area. El Bierzo, an intramontane basin in NE Spain, is partly filled by continental Tertiary sediments whose age is thought to be Vindobonian on the basis of comparison with those of the Duero basin. These deposits were analysed by sedimentological methods: determination of grain-size, grain roundness, pebble composition, mineralogy of the light and heavy fractions and of the clays (by x-ray). In some places the Tertiairy deposits overlie deeply weathered Paleozoic rocks, considered to be the C-horizon of paleosols of Tertiary age from which the red and more clayey A and B zones have disappeared. The latter, together with unweathered rocks, are thought to be the source material of the Tertiary beds. Five different facies have been distinguished in the Miocene deposits. In the SW there are red-brown conglomerates with pebbles consisting partially of shale (Las Médulas facies). The main mass of the basin sediments are mostly silts and clayey silts with some gravels, the sandy fractions again consisting mainly of shale fragments (Santalla facies). These deposits are therefore thought to derive from the the same source as those of Las Médulas and to represent the finer fractions which were transported farther. Near the borders of the basin there are some local grey calcareous deposits containing breccias that are assumed to have been formed near faults (Vega de Espinareda facies). On top of the beds in the Santalla facies there are again local conglomerates of a more yellow colour (Fresnedo facies). The Astorga-facies, lastly, forms a transition to the deposits of the Duero basin in the E; it contains red conglomerates as well as sands and silts. Among the clay minerals, illite usually predominates as in the source rocks, but in the stagnant waters of the basin centre montmorillonite was formed as well. Towards the E there is an increasing kaolinite content, and in one case a considerable amount of attapulgite was found. The heavy minerals are for the most part the common resistant species, with the addition of anatase (which occurs in lateritic soils) in the Astorga facies. These facts suggest that the Tertiary soil-forming processes were more intense (i.e. lateritic in type) in the eastern part than in the Bierzo basin proper. Sedimentation started when some parts of the Miocene relief, covered by a thick soil, began to rise and were partly eroded, and others subsided so as to form an area of sedimentation. Remains of the Early Miocene topography are preserved in various places as surfaces with low relief on which remainders of Tertiary deposits and deep weathering are found. The most important of these is the Brañuelas surface, a plateau separating the Bierzo from the Duero basin. This plateau must once have been covered by Miocene sediments, which means that the deposits of both areas were connected and that drainage took place towards the E. After the tectonic movements that affected the Bierzo basin towards the end of the Miocene, the connection was severed and the drainage direction was reversed to the W. Later, probably during the Villafranchian, pediments on the lower slopes of the uplifted mountain masses were covered by thin angular gravels(raña’s) and fanglomerates, and the erosion surfaces were remodelled. During the remainder of the Quaternary, five terrace levels were formed in the easily erocable deposits of the Bierzo, and the partial evacuation of the basin deposits was accomplished.

Description: In 1968 continuous seismic profiles with a total length of 150 km were made in the Ría de Arosa (Galicia, NW Spain). They were executed by the Bundesanstalt für Bodenforschung (Hannover) with the assistance of two members of the Department of Geology of the University of Leiden (The Netherlands). The pneuflex (airgun) system used for profiling is described. The transformation of travel-time profiles into depth profiles was done automatically with the aid of a computer program. The profiles reveal the presence, below some 7—12 m of Holocene marine muds, of bedded deposits with a thickness of about 30 m (and in the outer part of the ria even more than 60 m), which are interpreted as being of fluvial origin. They are underlain by what is assumed to be colluvium and weathered granite. The bedded deposits must have been formed in times when the sea-level was low, presumably during the Riss and/or Würm glacials. They may originate in part from deposits of the Ulla River, but to a greater extent may represent fluvial fans of its tributaries.

Description: Investigaciones en la Ría de Arosa y sus alrededores, 1962—1964. Introducción. En los veranos de 1962 y 1963 y en el invierno y verano de 1964 un grupo científico holandés hizo investigaciones sedimentológicas, oceanógraficas, zoológicas y botánicas en la Ría de Arosa y sus alrededores. Se tomaron muestras en 934 localidades indicadas en el mapa (Apéndice I). Los nombres de los participantes han sido mencionados en el Apéndice II. El centro de las investigaciones era la fábrica de Don Luis Losada Lago en la Punta Preguntoiro en Villajuán cerca de Villagarcía de Arosa. En el texto siguiente se mencionan los periódicos en que serán publicados los resultados.

Description: This paper is intended to provide a geomorphological introduction to a series of papers on the sedimentology and weathering phenomena of the Ría de Arosa area. The area contains a large mass of coarse-grained porphyritic granite surrounded by other crystalline rocks. The granite is deeply weathered and displays typical features such as spheroidal weathering and tors. The main relief elements are the following. (a) Low-angle slopes, many of which are foot-slopes (glacis) developed mainly on deeply weathered rock, and covered in many parts by colluvium and bedded slope-deposits (Nonn 1964). The latter locally continue below the present sea-level as kaolinite deposits. The low-angle slopes occupy a large area on the intrusive granite around the Ría de Arosa. (b) Rounded residual hills. (c) Mountain massifs in metamorphic rocks and migmatites, with steep slopes and flatter top-surfaces which are perhaps remains of a peneplain. The distribution of these features is given on the geomorphological map. The drainage pattern has been strongly influenced by some of the fracture directions of the basement rocks and by late-Tertiary faults. The latter broke up a Tertiary peneplain and created a long N-S rift. It may also have affected the coast and influenced the bottom topography around the Galicia Bank (Black et al. 1964). The main rivers maintain their original SW directions at the points where they cross the rift. Because these points had been lowered by subsidence of the rift zone, the downstream parts of the valleys, now occupied by the rias, became antecedent valleys in the rising block W of the rift. It is not necessary to assume individual subsidence of each of the rias. The valleys may be merely the result of denudation and erosion which processes must have continued on the present ria bottoms during the glacials when the sea-level was lowered. The rias must have existed in at least the last two interglacials, and probably much earlier (Mensching 1961); there are no indications of differential tectonic movements since then.

Description: In dem Fossilverzeichnis sind die Arten in der Regel unter dem Namen aufgeführt den sie in der neuesten bei der Art zitierten Arbeit tragen ¹). Wenn eine Art in früheren Arbeiten über Niederländisch Indien anders benannt worden ist, so findet man die Nummern dieser älteren Arbeiten doch hinter dem neueren Artnamen. Der ältere, hinfällige Name ist in solchen Fallen in einer Bemerkung zu finden, ausserdem aber ist er auch in dem Artenverzeichnis aufgenommen, aber dort nur von einem Hinweis nach dem neueren Namen versehen, wo man also die zugehörige Literatur findet. Wenn von einer früher beschriebenen Art einige wenige Exemplare nach neuerer Bearbeitung zu einer anderen, schon vom selben Fundort bekannten Art gebracht worden sind, so sind diese wenigen Exemplaren bei der Aufzählung der Synonymen dieser beiden Arten nicht berücksichtigt.

Description: Investigaciones en la R\xc3\xada de Arosa y sus alrededores, 1962\xe2\x80\x941964. Introducci\xc3\xb3n.\nEn los veranos de 1962 y 1963 y en el invierno y verano de 1964 un grupo cient\xc3\xadfico holand\xc3\xa9s hizo investigaciones sedimentol\xc3\xb3gicas, ocean\xc3\xb3graficas, zool\xc3\xb3gicas y bot\xc3\xa1nicas en la R\xc3\xada de Arosa y sus alrededores. Se tomaron muestras en 934 localidades indicadas en el mapa (Ap\xc3\xa9ndice I). Los nombres de los participantes han sido mencionados en el Ap\xc3\xa9ndice II. El centro de las investigaciones era la f\xc3\xa1brica de Don Luis Losada Lago en la Punta Preguntoiro en Villaju\xc3\xa1n cerca de Villagarc\xc3\xada de Arosa. En el texto siguiente se mencionan los peri\xc3\xb3dicos en que ser\xc3\xa1n publicados los resultados.

Description: This paper is intended to provide a geomorphological introduction to a series of papers on the sedimentology and weathering phenomena of the R\xc3\xada de Arosa area.\nThe area contains a large mass of coarse-grained porphyritic granite surrounded by other crystalline rocks. The granite is deeply weathered and displays typical features such as spheroidal weathering and tors.\nThe main relief elements are the following. (a) Low-angle slopes, many of which are foot-slopes (glacis) developed mainly on deeply weathered rock, and covered in many parts by colluvium and bedded slope-deposits (Nonn 1964). The latter locally continue below the present sea-level as kaolinite deposits. The low-angle slopes occupy a large area on the intrusive granite around the R\xc3\xada de Arosa. (b) Rounded residual hills. (c) Mountain massifs in metamorphic rocks and migmatites, with steep slopes and flatter top-surfaces which are perhaps remains of a peneplain. The distribution of these features is given on the geomorphological map.\nThe drainage pattern has been strongly influenced by some of the fracture directions of the basement rocks and by late-Tertiary faults. The latter broke up a Tertiary peneplain and created a long N-S rift. It may also have affected the coast and influenced the bottom topography around the Galicia Bank (Black et al. 1964).\nThe main rivers maintain their original SW directions at the points where they cross the rift. Because these points had been lowered by subsidence of the rift zone, the downstream parts of the valleys, now occupied by the rias, became antecedent valleys in the rising block W of the rift. It is not necessary to assume individual subsidence of each of the rias. The valleys may be merely the result of denudation and erosion which processes must have continued on the present ria bottoms during the glacials when the sea-level was lowered. The rias must have existed in at least the last two interglacials, and probably much earlier (Mensching 1961); there are no indications of differential tectonic movements since then.

Description: SEDIMENTOLOGY AND GEOMORPHOLOGY OF EL BIERZO (NW SPAIN) The purpose of this investigation was to study sedimentation in an intramontane basin in its relation to the relief of the surrounding mountain area.\nEl Bierzo, an intramontane basin in NE Spain, is partly filled by continental Tertiary sediments whose age is thought to be Vindobonian on the basis of comparison with those of the Duero basin. These deposits were analysed by sedimentological methods: determination of grain-size, grain roundness, pebble composition, mineralogy of the light and heavy fractions and of the clays (by x-ray).\nIn some places the Tertiairy deposits overlie deeply weathered Paleozoic rocks, considered to be the C-horizon of paleosols of Tertiary age from which the red and more clayey A and B zones have disappeared. The latter, together with unweathered rocks, are thought to be the source material of the Tertiary beds.\nFive different facies have been distinguished in the Miocene deposits. In the SW there are red-brown conglomerates with pebbles consisting partially of shale (Las M\xc3\xa9dulas facies). The main mass of the basin sediments are mostly silts and clayey silts with some gravels, the sandy fractions again consisting mainly of shale fragments (Santalla facies). These deposits are therefore thought to derive from the the same source as those of Las M\xc3\xa9dulas and to represent the finer fractions which were transported farther. Near the borders of the basin there are some local grey calcareous deposits containing breccias that are assumed to have been formed near faults (Vega de Espinareda facies). On top of the beds in the Santalla facies there are again local conglomerates of a more yellow colour (Fresnedo facies). The Astorga-facies, lastly, forms a transition to the deposits of the Duero basin in the E; it contains red conglomerates as well as sands and silts.\nAmong the clay minerals, illite usually predominates as in the source rocks, but in the stagnant waters of the basin centre montmorillonite was formed as well. Towards the E there is an increasing kaolinite content, and in one case a considerable amount of attapulgite was found. The heavy minerals are for the most part the common resistant species, with the addition of anatase (which occurs in lateritic soils) in the Astorga facies. These facts suggest that the Tertiary soil-forming processes were more intense (i.e. lateritic in type) in the eastern part than in the Bierzo basin proper.\nSedimentation started when some parts of the Miocene relief, covered by a thick soil, began to rise and were partly eroded, and others subsided so as to form an area of sedimentation. Remains of the Early Miocene topography are preserved in various places as surfaces with low relief on which remainders of Tertiary deposits and deep weathering are found. The most important of these is the Bra\xc3\xb1uelas surface, a plateau separating the Bierzo from the Duero basin. This plateau must once have been covered by Miocene sediments, which means that the deposits of both areas were connected and that drainage took place towards the E. After the tectonic movements that affected the Bierzo basin towards the end of the Miocene, the connection was severed and the drainage direction was reversed to the W.\nLater, probably during the Villafranchian, pediments on the lower slopes of the uplifted mountain masses were covered by thin angular gravels(ra\xc3\xb1a\xe2\x80\x99s) and fanglomerates, and the erosion surfaces were remodelled. During the remainder of the Quaternary, five terrace levels were formed in the easily erocable deposits of the Bierzo, and the partial evacuation of the basin deposits was accomplished.

Description: In 1968 continuous seismic profiles with a total length of 150 km were made in the R\xc3\xada de Arosa (Galicia, NW Spain). They were executed by the Bundesanstalt f\xc3\xbcr Bodenforschung (Hannover) with the assistance of two members of the Department of Geology of the University of Leiden (The Netherlands). The pneuflex (airgun) system used for profiling is described. The transformation of travel-time profiles into depth profiles was done automatically with the aid of a computer program.\nThe profiles reveal the presence, below some 7\xe2\x80\x9412 m of Holocene marine muds, of bedded deposits with a thickness of about 30 m (and in the outer part of the ria even more than 60 m), which are interpreted as being of fluvial origin. They are underlain by what is assumed to be colluvium and weathered granite. The bedded deposits must have been formed in times when the sea-level was low, presumably during the Riss and/or W\xc3\xbcrm glacials. They may originate in part from deposits of the Ulla River, but to a greater extent may represent fluvial fans of its tributaries.

Description: In dem Fossilverzeichnis sind die Arten in der Regel unter dem Namen aufgef\xc3\xbchrt den sie in der neuesten bei der Art zitierten Arbeit tragen \xc2\xb9). Wenn eine Art in fr\xc3\xbcheren Arbeiten \xc3\xbcber Niederl\xc3\xa4ndisch Indien anders benannt worden ist, so findet man die Nummern dieser \xc3\xa4lteren Arbeiten doch hinter dem neueren Artnamen. Der \xc3\xa4ltere, hinf\xc3\xa4llige Name ist in solchen Fallen in einer Bemerkung zu finden, ausserdem aber ist er auch in dem Artenverzeichnis aufgenommen, aber dort nur von einem Hinweis nach dem neueren Namen versehen, wo man also die zugeh\xc3\xb6rige Literatur findet.\nWenn von einer fr\xc3\xbcher beschriebenen Art einige wenige Exemplare nach neuerer Bearbeitung zu einer anderen, schon vom selben Fundort bekannten Art gebracht worden sind, so sind diese wenigen Exemplaren bei der Aufz\xc3\xa4hlung der Synonymen dieser beiden Arten nicht ber\xc3\xbccksichtigt.