The last maximum ice extent and subsequent deglaciation of the Pyrenees: an overview of recent research

Delmas, Magali

doi:10.18172/cig.2708

Cited by 51 publications

(43 citation statements)

References 51 publications

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“…20.000 años BP) está empezando a ser bien conocido (Delmas, 2015). La cartografía geomorfológica indica la presencia de numerosos depósitos morrénicos frontales y laterales correspondientes a reavances posteriores al máximo (Serrano-Cañadas, 1991;Martínez de Pisón & Serrano, 1997;García-Ruiz et al, 2001b.…”

Section: Fluctuaciones Climáticas Durante El Pleistoceno Superiorunclassified

Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales

García‐Ruiz¹,

López‐Moreno²,

Lasanta³

et al. 2015

Pirineos

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. Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales. Pirineos, 170, e012. doi: http://dx.doi.org/10.3989/Pirineos.2015.170005 RESUMEN: Se revisan los efectos de la evolución del clima y los cambios de uso del suelo / cubierta vegetal en el Pirineo Central español a diferentes escalas espaciales y temporales. Los estudios paleoclimáticos, basados en análi-sis multiproxy de sedimentos lacustres, glaciares, espeleotémicos y registros dendrológicos, entre otros, han demostrado la ocurrencia de importantes fluctuaciones climáticas durante la deglaciación de finales del Pleistoceno Superior y durante el Holoceno, afectando a la distribución de la vegetación, la generación de escorrentía, la frecuencia de avenidas y las formas de organización del espacio por parte de las sociedades humanas, en particular durante el evento 8.2, la Edad del Bronce, la Anomalía Climática Medieval y la Pequeña Edad del Hielo. El estudio del impacto de las actividades humanas sobre la dinámica del paisaje en el último siglo y medio ha revelado cambios espectaculares en la estructura y distribución de la vegetación, tanto en el piso montano como en el subalpino y, consecuentemente, cambios en la generación de escorrentía, la intensidad de la erosión del suelo y las fuentes de sedimento, cualquiera que sea la escala espacial a la que se contempla el problema. De forma general puede afirmarse que a mediados del siglo xix se alcanza la máxima presión sobre el territorio, cultivándose todas las laderas posibles hasta una altitud aproximada de 1650 m s.n.m. y empleando frecuentemente el fuego para limitar la expansión de matorrales en zonas de pastos, lo que dio lugar a intensos procesos de erosión y degradación del suelo, y al desarrollo de ríos trenzados con una elevada torrencialidad. Posteriormente, el abandono de tierras de cultivo desde comienzos del siglo xx (y, en especial, desde la década de 1960) y el descenso de la presión ganadera han favorecido la revegetación de las antiguas áreas de cultivo y pastos bien por avance de formaciones naturales de matorral y bosque, bien por la reforestación artificial de extensas laderas, ascendiendo el treeline en el piso subalpino, en este último caso

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Section: Fluctuaciones Climáticas Durante El Pleistoceno Superiorunclassified

Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales

García‐Ruiz¹,

López‐Moreno²,

Lasanta³

et al. 2015

Pirineos

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“…A time lag between the maximum ice extent in the Pyrenees (> 40 ka) recorded during MIS 4, and the global Last Glacial Maximum (LGM) culminating ca. 21 ka during MIS 2 (Mardones and Jalut, 1983;Montserrat-Martí, 1992;Bordonau, 1992;García-Ruiz et al, 2003;Calvet et al, 2011;Delmas, 2015;Turu et al, 2016) has been proved for the Pyrenean glaciers. In the Garona valley, the glaciolacustrine and till deposits at the base of the Barbazan Lake fill sequence, about 30 km downstream of Les, have yielded an age of 31.16 ± 1.7 ka BP (32.037 to 39.407 ka cal BP), showing the presence of a glacier on that site until 26.6 ± 0.46 ka BP (29.786 to 31.446 ka cal BP) (Andrieu et al, 1988;Jalut et al, 1992).…”

Section: Geological and Geomorphological Settingmentioning

confidence: 97%

“…70 km reaching the Aquitaine foreland basin (Mianes, 1955;Calvet et al, 2011;Stange et al, 2014b;Delmas, 2015). In Val d'Aran, located at the upper part of the glacial basin, a minimum ice thickness of about 800 m has been estimated between Vielha and Les Bordes (Fig.…”

Section: Postglacial Geomorphological Evolutionmentioning

confidence: 99%

Long-term entrenchment and consequences for present flood hazard in the Garona River (Val d'Aran, Central Pyrenees, Spain)

Victoriano

Garcia-Silvestre

Furdada

et al. 2016

Nat. Hazards Earth Syst. Sci.

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Abstract. On 18 June 2013, a damaging flood of the Garona River (Val d'Aran, Central Pyrenees, Spain) caused losses exceeding EUR100 million. Few studies have related flood events to the geologic, tectonic and geomorphologic context. This study deals with both short-and long-term processes by studying the upper reach of the Garona River on different timescales and space scales. There has been a clear entrenchment tendency of the drainage network since the Miocene. Post-orogenic exhumation and uplift of the Axial Pyrenees determines the recent and active tectonics of the area and leads to fluvial incision. The last Upper Pleistocene glaciation affected Val d'Aran and gave rise to a destabilization period during the glacial-interglacial transition, marked by a postglacial incision tendency. Mean entrenchment rates between 0.68 and 1.56 mm yr −1 since deglaciation have been estimated. The assessment of the 2013 flood, characterized by the predominance of vertical incision and bank erosion, suggests that the long-term tendency of the fluvial system is reflected in short-term processes. The study of the geologic and geomorphologic evolution, combined with the analysis of this 30-50-year return period flood event, helps to improve flood risk management by providing contextual information that can constrain predictions and help guide choices and decisions. In fact, the millennial entrenchment tendency is shown at the human scale, which is considered useful for river management, but could be imperceptible in detailed hydrodynamic and channel morphology studies that describe river dynamics mostly at the 10-15-year timescale.

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“…Contrary to the neighbouring Garonne valley, the Neste valley is believed to have mostly been exempt of glaciers during the Quaternary, and no glacial features are known on the megafan itself (e.g. Delmas, 2015).…”

Section: The Lannemezan Megafanmentioning

confidence: 99%

Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan–mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (northern Pyrenees, France)

et al. 2017

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Abstract. Alluvial megafans are sensitive recorders of landscape evolution, controlled by both autogenic processes and allogenic forcing, and they are influenced by the coupled dynamics of the fan with its mountainous catchment. The Lannemezan megafan in the northern Pyrenean foreland was abandoned by its mountainous feeder stream during the Quaternary and subsequently incised, leaving a flight of alluvial terraces along the stream network. We use numerical models to explore the relative roles of autogenic processes and external forcing in the building, abandonment and incision of a foreland megafan, and we compare the results with the inferred evolution of the Lannemezan megafan. Autogenic processes are sufficient to explain the building of a megafan and the long-term entrenchment of its feeding river on time and space scales that match the Lannemezan setting. Climate, through temporal variations in precipitation rate, may have played a role in the episodic pattern of incision on a shorter timescale. In contrast, base-level changes, tectonic activity in the mountain range or tilting of the foreland through flexural isostatic rebound do not appear to have played a role in the abandonment of the megafan.

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The last maximum ice extent and subsequent deglaciation of the Pyrenees: an overview of recent research

Cited by 51 publications

References 51 publications

Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales

Los efectos geoecológicos del cambio global en el Pirineo Central español: una revisión a distintas escalas espaciales y temporales

Long-term entrenchment and consequences for present flood hazard in the Garona River (Val d'Aran, Central Pyrenees, Spain)

Autogenic versus allogenic controls on the evolution of a coupled fluvial megafan–mountainous catchment system: numerical modelling and comparison with the Lannemezan megafan system (northern Pyrenees, France)

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