FIGURE 1 - uploaded by Marc Oliva
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Sketch with the location of the study areas in Sierra Nevada in which solifluction landforms are distributed. Example of a solifluction lobe formed below a snow patch.
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In the highest land of the Sierra Nevada National Park, an experiment to monitor solifluction
rates together with the thermal regime of the ground was implemented during the
period 2005–2011. Data show evidence of the low activity of solifluction processes in
the present-day periglacial belt of Sierra Nevada. Annual displacement rates were lower
th...
Contexts in source publication
Context 1
... landforms are distributed in the headwaters of the highest glacial valleys in Sierra Nevada. They show a large variety of morphologies and dimensions, and the majority is densely vegetated ( Oliva et al., 2009). Up to 17 solifluction features concentrated in four study areas from San Juan and Rio Seco valleys have been monitored in this study (Fig. 1). These solifluction landforms are turf-banked lobes, ...
Context 2
... distribution of long-lying snow patches in Sierra Nevada is strongly controlled by the orientation of the valleys, with north- erly exposed valleys having longer duration of snow cover (Oliva, 2009). In Sierra Nevada, solifluction landforms are mostly distrib- uted below snow patches, as can be seen in Figure 1. The proxim- ity of solifluction landforms to snow patches lengthens the water runoff period, which in turn enhances slow mass movement per- iglacial processes during late spring and early summer. ...
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... Where there are landslide scars in the cliff face that persist until the onset of winter, snow accumulation is greater in these scars. As some authors have pointed out, snow can, on the one hand, protect against erosion associated with daily thermal variations, but, on the other hand, its melting in spring can promote hydrogeological processes that can lead to geomorphological processes of greater magnitude in the cliff [47,102,103]. play a significant role in cliff erosion. Retreat events can thus take place in all seasons. ...
This article focuses on the quantification of retreat rates, geomorphological processes, and hydroclimatic and environmental drivers responsible for the erosion of an unconsolidated fine-sediment cliff along the north shore of the Gulf of St. Lawrence (Quebec, Canada). Annual monitoring using field markers over a period of twenty years, coupled with photo interpretation and historical archive analysis, indicates an average annual erosion rate of 2.2 m per year between 1948 and 2017. An acceleration in retreat occurred during the last 70 years, leading to a maximum between 1997 and 2017 (3.4 m per year) and 2000–2020 (3.3 m per year). Daily observations based on six monitoring cameras installed along the cliff between 2008 and 2012 allowed the identification of mechanisms and geomorphological processes responsible for cliff retreat. Data analysis reveals seasonal activity peaks during winter and spring, which account for 75% of total erosional events. On an annual basis, cryogenic processes represent 68% of the erosion events observed and subaerial and hydrogeological processes account for 73%. Small-scale processes, such as gelifraction, solifluction, suffosion, debris collapse, and thermoabrasion, as well as mass movement events, such as slides and mudflows, induced rapid cliff retreat. Lithostratigraphy and cliff height exert an important control on erosion rates and retreat modes, which are described by three main drivers (hydrogeologic, cryogenic, and hydrodynamic processes). Critical conditions promoting high erosion rates include the absence of an ice-foot in winter, the absence of snow cover on the cliff face allowing unrestricted solar radiation, the repetition of winter warm spells, snow melting and sediment thawing, and high rainfall conditions (>30 mm or SPI > 2). The relationships between hydroclimatic forcing and retreat rates are difficult to establish without taking into account the quantification of the geomorphological processes involved. The absence of quantitative data on the relative contribution of geomorphological processes can constitute a major obstacle in modeling the retreat of cliffs with regard to climate change.
... Due to the fact that nivation processes are generally operating slowly and on a long timescale, presumably their effect might be combined with or superseded by the effect of either faster-working periglacial processes such as creep, solifluction, or earth flows (Matsuoka, 2001;Oliva et al., 2014); or wind action, which is an important geomorphic agent within hot deserts as well as the conditions of cold semi-arid to arid climates (McKenna Neuman, 1993;Seppälä, 2004). Therefore, the effect of nivation alone may be hard, if not impossible, to quantify in most places. ...
In this study, we aim to describe geomorphological processes related to snow patches in the ice-free environment of James Ross Island located in Maritime Antarctica. The area of interest for this study is situated on Cape Lachman and consists of an approximately 1500 m long and 300 m wide oval-shaped depression with two shallow lakes at the bottom. Due to the varied aspect of the slopes, large snow accumulations form in the southern part of the depression, where the slopes exhibit a lee aspect towards the prevailing southwestern wind. Within the semi-arid conditions of James Ross Island, the redistribution of snow by wind and the availability of moisture from the melting snow play a key role in shaping of the landscape. Via repeated UAV surveys, field campaigns and construction of a digital terrain model of the study area, we were able to identify the specific landforms that have been shaped by nival processes, such as winnowing of the fine material and its subsequent transport downslope; and mass-wasting, resulting from slumping of the meltwater-saturated active layer. We developed a three-step model of landscape evolution throughout the Holocene, which helps to explain how snow-related processes contribute to landscape shaping within the ice-free environment of James Ross Island.
... 22 Early studies of geomorphological processes related to cold climates in the Iberian Peninsula focused on geomorphological mapping, description, and relative dating of relict landforms and slope deposits. [23][24][25][26][27][28][29][30][31][32][33] Recently, monitoring of present-day processes has increased in the Iberian Peninsula mountains, [34][35][36] but only a few studies provide absolute dating of periglacial features. 21 The complexity of factors such as rough orography, high Holocene erosion rates and land degradation, has made it difficult to provide a chronological framework for the sedimentation, and additional geographic locations need to be investigated to allow reconstruction of the regional characteristics of Iberian periglacial paleoenvironments. ...
The paper focuses on analysis of macro‐ and micromorphological characteristics of relict slope deposits in Serra da Estrela (Portugal) to understand the significance of different slope processes and paleoenvironmental settings. Micromorphology is a useful sedimentology technique allowing significant advances compared to macroscopic techniques. Results show that different processes are involved in the development of the slope deposits, reflecting different environmental conditions. The main processes responsible for the emplacement of the relict slope deposits are solifluction, debris‐flow and runoff, but postdepositional changes are also present. Solifluction was identified in slope deposits between 650 and 1500 m a.s.l. The common microfeatures identified are circular arrangement of grains with a core grain, rounded vesicles, vertical grains, matrix deformations and fine‐grained deposits. Slope deposits above 1300 m a.s.l have a platy microstructure and coincide with the altitudinal range of the relict rock glaciers, indicating the elevation limit of permafrost. Below this altitude platy microstructures are less frequent. Slope deposits in north‐facing slopes were affected by frost‐induced processes in a seasonal frost regime, followed by a postdeposition illuvial phase. Debris‐flow and runoff were identified in slope deposits between 680 and 1260 m a.s.l. The common microfeatures are oblique grains, grain dumps, and coarse and fine grain lineations, and banded microstructures were identified in runoff processes. Debris‐flow deposits have a circular arrangement of grains without a core grain, identified in sediments in paraglacial and periglacial environments. The slope deposits show evidence of past periods of enhanced periglacial activity since the last glaciation until the Younger Dryas.
... The headwaters of both valleys were heavily glaciated during the Last Glaciation, and wetlands formed during the Holocene including abundant solifluction features, generally next to long-term snow patches. 29 ...
... We update data and provide the most extensive and complete review of the thermal regime of a southern massif in Europe, complementing previous works. [18][19][20][21]27,[29][30][31][32][33][34][35] ...
Outside the Alps, the Sierra Nevada is probably the best studied European massif with respect to its past and current environmental dynamics. A multi‐approach research program started in the early 2000s focused on the monitoring of frozen ground conditions in this National Park. Here, we present data on the thermal state and distribution of permafrost and seasonal frozen ground in different sites across the highest areas of the massif. New results confirm the absence of widespread permafrost conditions, with seasonal frost prevailing above 2500 m. Small permafrost patches have been only detected in glaciated areas of the Veleta and Mulhacén cirques during the Little Ice Age at elevations of 3000–3100 m. The remnants of those glaciers are still preserved under the thick debris layer covering the cirque floors. Geomatic and geophysical surveying of a rock glacier existing in the Veleta cirque, together with the monitoring of soil temperature at different depths, have revealed permanently frozen conditions undergoing a process of degradation. In the rest of the massif, a seasonal frost regime prevails, even at the highest plateaus at 3300–3400 m, where annual soil temperatures average 2.5°C. The monitoring of soil temperatures in other different periglacial features has also revealed positive average values ranging between 2°C (inactive sorted‐circles) and 3–4°C (inactive and weakly active solifluction lobes). Consequently, we conclude that the present‐day climatic regime does not allow the existence of permafrost in the Sierra Nevada, and environmental dynamics is controlled by the intensity and duration of seasonal frost in the ground.
... As in other mid-latitude mountain environments, periglacial processes in the Iberian ranges are strongly controlled by altitude and latitude, which in turn determines mean annual air temperature. In the high mountains of the western Mediterranean basin winter precipitation is a crucial factor for present-day periglacial activity since it influences the duration and thickness of snow cover, which control soil moisture and the ground thermal regime (Zhang, 2005;Oliva et al., 2014a). Linked to climate conditions, the vegetation type and cover and the degree of soil development, together with other local factors such as the lithology and topography, are also decisive for periglacial activity (Vieira et al., 2003). ...
... Most of the studies that have monitored periglacial processes in Iberian mountains have shown that periglacial landforms show a weakly active to inactive pattern (i.e., Oliva et al., 2014a), being only active in the highest northern cirques and watersheds (i.e., Serrano et al., 2006Serrano et al., , 2011bG omez-Ortiz et al., 2014). This means that the majority of the periglacial landforms and deposits formed during past periods with colder climate conditions that promoted very active periglacial processes. ...
... This is the case of a small rock glacier installed inside the Veleta cirque, which is undergoing rapid degradation due to the melting of the ice and the thawing of the permafrost located below (G omez- Ortiz et al., 1999Ortiz et al., , 2004. In all other environments of the massif, periglacial processes are driven by seasonal frost dynamics (Salvador-Franch et al., 2010Oliva et al., 2014a), with the formation of decimetric patterned ground features at the flat surfaces from 2700 m, debris flows, scree deposits and protalus ramparts (G omez -Ortiz, 2002;Tanarro et al., 2010). ...
This article focuses on the characterization of auriferous deposits, identification of hitherto unknown Roman mining infrastructure remains, and the early attempts of exploitation carried out in north-west Iberia. The research has combined airborne laser scanning (LiDAR) and field prospection to explore the geomorphological signature and landscape transformation resulting from Roman mining works in two unknown sectors of the western Duero Meseta. The integration of geological and remote sensing information contributed to extend the Roman's mining domains, traditionally focused on the river headwaters of the north-west. The article explores the complex hydraulic system developed in the Jamuz and lower sector of the Eria river valleys, as well as the evidence of open-cast mining and their relationship with the Roman army. The results suggest that the highly dispersed and reduced dimensions of the mining sites correspond to a selected method of gold prospection, employed for the identification of viable exploitation sectors. Thus, the initiation of the mining works could have started in the Jamuz valley and developed systematically in this area, to subsequently spread towards the upstream sectors and nearby valleys. This research contributes to gain new insights into the extension and complexity of the mining infrastructure, indicating the importance of the gold-bearing raña deposits within the framework of Roman gold mining in north-west Spain.
... The unconsolidated glacial sediments as well as the weathered bedrock also favour frequent mass movements, both as rapid and slow events. Processes such as rockfalls, landslides, gullying, debris flows and solifluction reshape the soil surface, particularly during the snow melting period as also occurs in the cryonival belt of other mid-latitude mountain environments (Oliva et al., 2014;Fernandes et al., 2017). Along with particles mobilized by wind action in the piedmont, all these processes contribute sediments to the rivers. ...
The Pamir Mountains include peaks exceeding 7000 m, such as Lenin Peak (7134 m) in the northern Zaalai Range. Here, we examine the distribution of soils and geomorphological processes and landforms in its northern slope, from the highest glaciated environments until Alai valley floor. We present the first geomorphological map of the study area as well as an accurate description the main geomorphological units in order to reconstruct landscape dynamics in the area from Quaternary cold stages until present-day. Five main units are distributed: (1) valley floor (2900-3040 m), an area that must have been ice-free during Quaternary glaciations and is currently being reshaped by glaciofluvial processes, with a large alluvial fan reworked by aeolian activity; (2) hummocky terrain (3040-3500 m) including two moraine systems left by a piedmont glacier during the Last Glaciation as well as hilly deposits originated by a catastrophic rockfall event; (3) U-shaped glacial valley (3500-3800 m), including some moraine ridges as well as a sedimentary cover composed of glacial till that is being eroded by fluvial and mass-wasting processes; (4) high mountain valleys (up to 4600-4800 m) adjacent to the main valley floor with small cirque and alpine glaciers and widespread periglacial processes in ice-free environments; (5) glaciers flowing from the Lenin Peak summit until the foot of the mountain, where they form a debris-covered (surge-type) glacier. The existence of abundant glacial, periglacial and rockfall deposits (moraines, till, erratic boulders) allows inferring five different environmental stages since the Last Glaciation. The latest glacial advances took place during the 20th century and the Little Ice Age and deposited two moraine systems near the glacial front. The occurrence of active rock glaciers and protalus lobes indicates that the limit of permafrost conditions is now located at 3400-3500 m, with seasonal frozen ground in lower areas.
... El tramo altitudinal afectado debió suponer un desnivel en torno a 1000 m aglutinando dos ambientes periglaciares diferenciados. Uno inferior, dominando laderas hasta los 2800 m, con generalización de procesos de solifluxión (Oliva, 2009;Oliva et al., 2014), crio-reptación y presencia de neveros de fusión tardía. Otro superior, repartido en cumbres cimeras y cabeceras de barrancos. ...
Historical documents have shown their potential to infer the origin and evolution of the glacier existing in the Veleta cirque, in the massif of Sierra Nevada (Spain). This information encompasses written sources spanning from the 17th to the mid-20th centuries, and provides valuable knowledge about the Little Ice Age. These new data complement the already existing geomorphological knowledge about the natural system and landscape evolution in Sierra Nevada, particularly with regards to glacial geomorphic events in the summit areas. From a transdisciplinary methodological approach, the results show that the Veleta glacier was a singular geomorphic event that owed its existence to the particular environmental conditions of the high lands of Sierra Nevada, besides the favourable morpho-topographical setting, altitude, aspect as well as microclimate conditions prevailing in this area.
... The first studies on the glacial landscapes of Sierra Nevada date back from the late 19th and early 20th centuries (Schimper, 1849;Macpherson, 1875;Quelle, 1908;Obermaier, 1916). This research was complemented during the last decades with a multi-proxy scientific approach examining both the glacial and periglacial geomorphology, together with palynological, geochronological and sedimentological evidence (Gómez-Ortiz et al., 1992, 2012Oliva et al., 2009Oliva et al., , 2010Oliva et al., , 2011Oliva et al., , 2014aOliva et al., , 2014bOliva et al., , 2016aAnderson et al., 2011;Jiménez-Moreno and Anderson, 2012;Oliva and Gómez-Ortiz, 2012). Consequently, the wide comprehension of the spatial extent and chronology of cold-climate geomorphological processes in Sierra Nevada makes this massif one of the most studied mountain environments of the Iberian Peninsula (Oliva et al., 2014a). ...
... A wide range of solifluction landforms developed in the highest valleys during the last millennia at elevations between 2500 and 3000 m. Some of these landforms are highly vegetated today and others show a scarce vegetation cover on their surface, but they all show today displacement rates < 1 cm yr -1 (Oliva et al., 2014b). In general, periglacial processes are active nowadays above 2500 m, with active talus slopes due to a high number of freeze-thaw cycles (Gómez-Ortiz et al., 1998). ...
... Por otra parte, los lóbulos están condicionados por los factores climáticos, hidrológicos, geológicos y morfotopográficos (MATSUOKA, 2001), y en la alta montaña peninsular se ha constatado (BROSCHE, 1984;OLIVA y GÓMEZ ORTIZ, 2011;OLIVA et al., 2014) su dependencia de la pendiente, la cobertura vegetal, la disponibilidad hídrica, la duración y espesor del manto nival y el régimen térmico del suelo, pero en ambos casos asociados a suelos helados estacionales. El aporte hídrico procedente de la fusión nival satura o sobresatura los depósitos de finos, que pierden cohesión y reptan, en todo caso asociado a la presencia de suelo helado estacional en profundidad (HARRIS et al., 1997;MATSUOKA, 2001;OLIVA et al., 2008OLIVA et al., , 2009, de modo que el mayor desplazamiento se produce durante el deshielo, con procesos sincrónicos de crioreptación y gelifluxión. ...
... En Picos de Europa, en las zonas altas sobre derrubios calcáreos, los desplazamientos solifluidales varían entre 0,21 y 1,88 cm a -1 (BROSCHE, 1994), y en ambientes periglaciares marítimos de Escocia se han medido desplazamientos para 35 años entre 0,78 y 1 cm a -1 (medias de 0,88 cm a -1 ), que sugieren similares velocidades superficiales de los lóbulos de solifluxión y los bloques aradores, y ambas menores que en las zonas desprovistas de vegetación, donde la reptación por agujas de hielo (pipkrake) es el principal componente de la solifluxión (BALLANTYNE, 2013). En Sierra Nevada, en ambientes con suelos helados estacionales, los movimientos de los lóbulos son de ~0,5 cm a -1 y su desplazamiento se corresponde con procesos de centenares a miles de años, y dinámicas actuales asociadas a la saturación por fusión nival (OLIVA et al., 2008(OLIVA et al., , 2009(OLIVA et al., , 2014. ...
En Áliva (Picos de Europa, Montaña Cantábrica) se ha realizado un control de la dinámica de lóbulos de solifluxión, y bloques aradores. Los Puertos de Áliva se sitúan entre el grupo Peña Vieja, en el macizo central, y el macizo oriental o de Andara. Constituido por una sucesión de pizarras negras con intercalaciones de conglomerados calcáreos, calizas y are-niscas, la Formación Lebeña forma una depresión donde domina el modelado glaciar. En las laderas destacan los lóbulos, las terracillas, bloques aradores, acarcavamientos, deslizamientos de ladera y desprendimientos. Con el objetivo de conocer la dinámica geomorfológica actual en los Puertos de Áliva, y establecer la importancia de los procesos asociados al hielo en la transferencia de sedimentos y la erosión de suelos, se ha realizado un control geomático de lóbulos, bloques aradores, cárcavas y deslizamientos. Estos se complementan con registros tér-micos de suelos, análisis de la Estación Meteorológica Automática y cartografía geomorfológica. Las observaciones geomáticas se han realizado entre 2008 y 2015. La técnica empleada ha sido GPS-RTK y TLS. La zona se ha dividido en tres áreas de trabajo: parcela 1, medición de tres lóbulos; parcela 2, observación de dos bloques aradores y un lóbulo y parcela 3, con medición de cuatro bloques aradores. El desplazamiento de los lóbulos y bloques aradores, con promedios menores de 0,5 cm a-1 denotan una baja actividad. El régimen térmico del suelo señala la inexistencia o moderada presencia del hielo en el suelo, por ello se plantea la hipótesis de que correspondan a geoformas heredadas del pasado reciente, con condiciones ambientales más favorables a la actividad periglaciar y con una dinámica actual asociada a la acción nival.
... When snow melts, geomorphic activity intensifies. Such is the case of the mountains of Iberia, where periglacial dynamics is especially effective during the snow melting period when the ground can still be frozen and high water availability enhances erosion and mass-wasting processes (Oliva et al., 2009(Oliva et al., , 2014a. ...
The present study focuses on the analysis of the ground and near-rock surface air thermal conditions at the Forcadona glacial cirque (2227 m a.s.l.) located in the Western Massif of the Picos de Europa, Spain. Temperatures have been monitored in three distinct geomorphological and topographical sites in the Forcadona area over the period 2006–11. The Forcadona buried ice patch is the remnant of a Little Ice Age glacier located in the bottom of a glacial cirque. Its location in a deep cirque determines abundant snow accumulation, with snow cover between 8 and 12 months. The presence of snow favours stable soil temperatures and geomorphic stability. Similarly to other Cantabrian Mountains, the annual thermal regime of the soil is defined by two seasonal periods (continuous thaw with daily oscillations and isothermal regime), as well as two short transition periods. However, the results showed evidence of a significantly different annual thermal regime at the ground and near-rock surface air. Relatively stable soil thermal regimes were observed at the moraine and talus sites, while a more dynamic pattern was recorded at the rock wall site. Here, a higher interannual variability in the number of freeze–thaw days was also detected, which showed evidence of the important role of the snow cover as a ground surface insulator in the area. Seasonal frost conditions are widespread today in the high lands of the massif. No permafrost regime was detected in the area, though mean temperatures measured at 0.5 m depth at the Forcadona buried ice patch during 2006–07 (0.1 °C) suggest that permanent negative values may be reached at deeper layers.
