The climatic significance of rock glaciers

Abstract

To obtain knowledge on the typical regional climate for rock glacier initiation and growth, a number of diagnostic geomorphological associations of normal glaciers and rock glaciers are analysed in selected regions of central west Greenland, north‐east Greenland and Antarctica. In these study areas, active rock glaciers and normal glaciers occur in proximity, and meteorological data are at hand. In general, the overall climate at active rock glaciers is not significantly different from that at the equilibrium line of normal glaciers nearby; the mean annual air temperature at rock glaciers usually is only slightly higher, if at all, than at nearby ELAs, and also the annual regional precipitation is only slightly lower than at nearby glaciers. In a regional temperature–precipitation space, active rock glaciers therefore tend to plot close to ELAs for modern glaciers, although with a tendency towards somewhat drier environments. The typical rock glacier climate is not exactly continental as has often been argued; it is rather a dry to moderate humid climate with cool summers. An important difference appears to be that while glaciers typically are situated at sites with a local, high accumulation of snow in relation to the input of talus, the opposite is true for rock glaciers. The different locations of glaciers and rock glaciers are thus mainly controlled by topoclimatic differences, rather than being a result of regional climatic differences. The observational data are still geographically limited and require both quality improvement and testing from other regions with active rock glaciers, but the topographic position and altitudinal distribution of rock glaciers probably contain unique climatic information, much the same as normal glaciers do. Therefore, relict rock glaciers represent a potentially important source of palaeoclimatic information. © 1998 John Wiley & Sons, Ltd.

Chronology and palaeoenvironmental implications of the ice‐wedge pseudomorphs and composite‐wedge casts on the Magdalen Islands (eastern Canada)

“…ka BP were described by Liverman et al . () in Newfoundland, and inactive rock glaciers described as geomorphic indicators of past permafrost (Humlum ) were associated with the Younger Dryas in Maine (USA; Putnam & Putnam ) and the Gaspésie peninsula (Québec; Hétu & Gray ; Hétu et al . ).…”

Age and origin of ice-cored moraines in Jotunheimen and Breheimen, southern Norway: insights from Schmidt-hammer exposure-age dating

“…The overall convex‐upwards cross profile of ice‐cored moraine complexes and their formation in proglacial position on almost flat terrain are perhaps more characteristic of ice‐cored moraines than rock glaciers, though ‘glacier‐derived’ or ‘moraine‐derived’ rock glaciers certainly occur (e.g. Potter ; Vere and Matthews ; Whalley and Martin ; Barsch ; Humlum ; Berthling ; Lilleøren et al . ), and ice‐cored moraines may be transformed into rock glaciers if the moraines have sufficient thickness or are located on sufficiently steep slopes.…”

Permafrost Favorability Index: Spatial Modeling in the French Alps Using a Rock Glacier Inventory

“…The rock glaciers were inventoried using Bing satellite imagery (yearly updated and accessible via QGIS), IGN aerial orthophotography (available for 2013 and at 50 × 50 cm resolution) (IGN, 2013). The digitized outlines of the landforms included their rooting zones, i.e., the slopes that furnish the debris to the rock glaciers and where the ice-debris mixture is supposed to originate (Humlum, 1998). The activity status was judged according to morphologic indicators (Barsch, 1996;Scapozza, 2008).…”

“…The rooting zone is the area where the mixture of ice and debris is created, and due to an over-saturation with ice, permafrost creep starts generating the rock glacier (Barsch, 1996;Humlum, 1998). The hypothesis behind this was that the climatic conditions favorable for mountain permafrost existence are found primarily in the rooting zone of active rock glaciers.…”

“…The hypothesis behind this was that the climatic conditions favorable for mountain permafrost existence are found primarily in the rooting zone of active rock glaciers. In this way the model was considered to avoid bias by including the rock glaciers' dynamical processes that export permafrost toward lower altitudes and that depend not only on the local climate but also on the morphometric characteristics of the rock glaciers' catchment (Humlum, 1998;Matsuoka and Ikeda, 2001;Frauenfelder et al, 2003;Brenning, 2005;Janke and Frauenfelder, 2007;Cossart et al, 2010). The break between the talus and the typical morphology of an active rock glacier, dominated by ridges and furrows, was used as a morphological criterion to identify the lower limit of production areas.…”