Landscapes and landsystems: Rock glaciers in the mountain slope domain of South America

Abstract

Satellite imagery provides a basis for detailed geomorphological mapping using a landsystem approach for the study of mountain environment landscapes in the Andes. The optical precision now available in repeated Google Earth imagery shows that weathering of rock free-faces supplies debris to glacier systems of various sizes, from snow-patches to cirque and valley glaciers and rock glaciers. The debris supplied to glacier ice bodies gives a variety of landscape features in accord with the relative fluxes of debris and ice. Identification of features and mapping transects provide a means of implementing detailed landsystem analysis in remote mountain areas with field checking in glacigenic systems. Decimal latitude-longitude, [dLL], provides a robust way to identify and record features of interest. In the Andes, no evidence can be found for considering rock glaciers as permafrost-related features, they are best viewed as part of a debris-glacier-debris-covered-glacier to rock glacier continuum. Google Earth images show that the, sometimes complex, nature of rock glacier surfaces can be explained by debris accumulation on active glacier ice systems. Meltwater surface pools, developing over time, have formed in the surfaces of debris-covered glaciers and expose glacier ice cores. This is confirmed by field investigations. Rock glaciers develop in areas outside any high latitude permafrost presence being, clear from rock glacier and moraine systems down valley. The presence of rock glaciers as indicators of mountain permafrost is also falsified by the high geothermal heat flow in many high mountain areas of the Andes. These findings can, with precise geolocation, be brought together in the “Digital Earth” where geo-referenced locations can be viewed in Google Earth as part of information surfaces.