Talus instability in a recent deglaciation area and its relationship to buried ice and snow cover evolution (picacho del veleta, sierra nevada, spain)

Abstract

The southernmost glacier in Europe formed during the Little Ice Age at the foot of the north wall of Picacho del Veleta (3 398 m) in Sierra Nevada, in the southeast region of the Iberian Peninsula (lat. 37δ03‘N, long. 3δ22‘W). The glacier gradually retreated during the last century, leaving a large talus slope at the base of the wall. The unconsolidated material covering the ice masses acted as a thermal insulator. Recent bottom temperature of snow (BTS) analyses and drillings indicate that the ice still exists within the talus. Evidence from field observations made during the period 1995–2001, revealed that large mass movements occurred during the driest summers (1998 and especially, 1999 and 2000) when the talus was snow free. These conditions suggest a direct relationship between talus stability and thermal insulation from the snow cover in areas where buried ice or decaying marginal permafrost exists.

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

“…Unable to evacuate the debris provided by the bed erosion and weathering of the backwalls, these very small rag glaciers progressively became stagnant, downwasting and buried ice bodies (Bosson et al, 2015;Carrivick et al, 2015;Capt et al, 2016). With their regular concave topography and dominating stagnant lowering dynamic, les Rognes and Entre la Reille glaciers will likely transform into buried ice patches (Serrano et al, 2011), then talus slopes (Gomez et al, 2003) with the projected future deglaciation context (e.g., Huss and Hock, 2015). Conversely, Tsarmine glacier still retains a flow-dominant dynamic (Figure 6B), due to its larger thickness and the presence of a small accumulation area upslope.…”

Cubierta nival, permafrost y formación de flujos superficiales en un talud detrítico de alta montaña (Corral del Veleta, Sierra Nevada, España)

“…2). El talud está constituido por abundantes derrubios que proceden de la destrucción de la pared (meteorización intensa por gelifracción, caída libre y ocasionales desprendimientos de gran entidad) (Gómez et al, 2003). La forma del talud es escalonada pues los derrubios se acumulan cubriendo repisas estructurales.…”

“…Desde un punto de vista sedimentológico el talud está constituido por una mezcla de derrubios donde predomina la fracción de los bloques y cantos (Gómez et al, 2003). No obstante, cabe destacar la presencia de abundante material fino que proviene de la alteración de los micaesquistos, que por su composición mineralógica resultan muy vulnerables a la meteorización (Puga et al, 2007).…”

“…El talud, situado al pie de la pared norte que delimita el Pico del Veleta (Fig. 2), muestra una activa dinámica geomorfológica, según se ha detectado a lo largo de trabajos de campo realizados en los últimos diez años (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008), en los que se ha podido observar el desarrollo de frecuentes movimientos en masa, entre los cuales destaca la formación de flujos rápidos pero muy superficiales, junto con deslizamientos rotacionales (Gómez et al, 2003). Esta creciente actividad geomorfológica del talud podría estar relacionada con la desprotección de la nieve durante el período estival en estos últimos años y la consecuente degradación del permafrost subyacente.…”

The Debeli Namet glacier (Durmitor, Montenegro) – from the second half of the 20th century to the present

“…They display similar characteristics: small spatial extents, underdeveloped tongues and widths commonly exceeding their lengths. They have been described as the Pyrenean type (Meccerli 1967) and were studied in the Pyrenees (Grove and Gellatly1995;Grove 2004), in the Sierra Nevada (Gómez et al 2003), in Picos de Europa (González-Trueba 2004) in Spain, in the Alpes Maritimes in France (Federici and Stefanini 2001), in the Italian Apennines (D'Orefice et al 2000;Dramis et al 2002;D'Alessandro et al 2003;Pecci 2006;Pecci et al 2008), in the Slovenian Alps ([ifrer 1976;Tintor 1993;Gams 1994;Gabrovec 1998;Pav{ek 2007;Triglav ^ekada et al 2012), in Durmitor Mountains in Montenegro (Djurovi} 1996;1999;2010), in Prokletije Mountains in Albania (Milivojevi} et al 2007;Hughes 2008), in Pirin Mountains in Bulgaria Gachev 2009;Gachev et al 2009;Grünewald and Scheithauer 2010) and elsewhere. Several smaller glaciers existed beyond the Debeli Namet glacier during the LIA on Durmitor Mountain but subsequently disappeared (Hughes 2010).…”