Analyse de la structure d'un glacier rocheux du domaine tropical (Caquella, sud-Lipez, Bolivie)

The analysis of a rock glacier structure in the tropical area (Caquella, South-Lipez, Bolivia)

¹ LIRIGM, Grenoble
² IRD, ORSTOM, Quito
³ UMR 8591, Meudon
⁴ Université Paris 1 & UMR 8591
⁵ IRD, ORSTOM, La Paz
⁶ Université de Milan
⁷ CEMAGREF, Grenoble

Abstract

The Caquella rock glacier (5960-5400 m asl), by the size (one kilometre long) is probably the most important active rock glacier in the Inner Tropics. In this arid high mountain environment glaciers are lacking and rock glaciers represent, with the salt lakes, the best indicators of the climatic variability. Moreover, they behave as water reservoirs in the present hydrological cycle marked by very scarce precipitation. Direct observations and geoelectrical soundings make it possible to identify interstitial ice in the permafrost. Nevertheless, the resistivity curve profile, the ice distribution in the debris mass as well as observations from the surface topography, bring clear evidences that this rock glacier is in recession. The Caquella rock glacier results from a long evolution, which has probably its origin in the early Holocene. Presence of a very recent moraine in the upper part suggests presence of ELA on the rock glacier during the Little Ice Age.