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In the Drakensberg Range of eastern Lesotho, periglacial sorted circles, stone-banked and turf-banked lobes, blockfields, block streams and wetland thúfur (earth hummocks) are present. These features are of varying ages (likely from Last Glacial Maximum to contemporary) and have been disturbed by soil formation and vegetation growth. This study uses a mixed methodology to investigate relationships between periglacial landforms, slope aspect and their associated ecosystems, and the relative age relationships of these components at Mafadi Peak on the Lesotho-South Africa border. A distinctive alpine flora, belonging to the Drakensberg Alpine Centre of the wider Afromontane phytochorion, is found in association with different periglacial landforms. Vegetation quadrat analysis shows that slope and aspect have no significant effect on vegetation cover, plant species abundance and bare ground cover. The most likely microscale relationships are with surface geomorphic features. The relative surface hardness and thus age of clasts within and outside of the stone/turf-banked lobes show that even within single landforms, variations in weathering exist, likely related to episodic and seasonal alpine cryoturbation. Major soil physical properties (grain size, organic and C/N content) and soil depth were measured. Weathering and soil development, influenced by climate, provide a substrate for a nutrient-deficient, sparse alpine flora and vegetation assemblage. The relationships between periglacial geomorphology and alpine ecosystems are not well understood from southern African high mountain regions, but are important with respect to ecosystem responses to ongoing climate change. [ABSTRACT FROM AUTHOR]

For several decades, geomorphologists have focused on the functioning of geomorphic systems after deglaciation. The relative importance of paraglacial vs. periglacial processes has been highly debated. At present, the development of dating techniques allows to contribute to this debate. We reconstruct in this paper the geomorphic evolution of Tindastóll mountain slopes in Laxárdalur valley (Skagafjörður area, central northern Iceland), where a chronological framework can be established through tephrochronology and an assemblage of dated raised beaches. Volumetric calculations of constructed and excavated landforms were created from field data and from DEM and geographical information system techniques. Collectively, our data exhibit a first stage of paraglacial landsliding during the first half of the Holocene, followed by a stage of scree and rockglacier development (during the second half of the Holocene, but before 1100 AD). Our estimations indicate that more than 85% of the total sediment production were due to rock slope failure, and the rate of bedrock denudation due to periglacial processes was about one half of the rate of paraglacial processes. Nevertheless, paraglacial and periglacial processes cannot be seen here as antagonistic processes: they are organized in a sequence during which periglacial processes are conditioned (enhancement of bedrock denudation rates) by fracturing and consequent mass wasting. Screes and concomitant rockglaciers were indeed preconditioned by the landslide, while areas non-affected by landslides have remained mostly intact, characterized by a very low rate of accumulation due to geomorphic (periglacial) activity. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper interprets a stone-banked lobe on the upper western face of Mt Rufus, at an altitude of 1380 m in western Tasmania, Australia. The morphology of the deposit resembles that of a solifluction lobe. Field observations show vertical and downslope movement of pebbles, cobbles and small boulders over a single winter season. The movement is largely related to frost pull (10-15 cm) and shallow freeze-thaw processes promoting the downslope (up to 50 cm yr-1) creep of material and the accumulation of coarse clasts at the lobe riser. The climate of Mt Rufus is strongly maritime and this is reflected in the limited duration and depth of penetration of frozen ground at this site during the 2013 winter. Despite the relatively mild climatic conditions, freeze-thaw processes are clearly the dominant geomorphic force operating at the site. These findings support observations of active stone-banked lobes on sub-Antarctic islands where intense freezing is absent. Both there and at Mt Rufus, movement is dominated by freeze-thaw processes operating in the upper c. 20 cm of the regolith. These are typical landforms of marginal freeze-thaw settings. [ABSTRACT FROM AUTHOR]

Sailer, R., Bollmann, E., Hoinkes, S., Rieg, L., Sproß, M. and Stötter, J., 2012. Quantification of geomorphodynamics in glaciated and recently deglaciated terrain based on airborne laser scanning data. Geografiska Annaler, Series A: Physical Geography, 94, 17-32. doi:10.1111/j.1468-0459.2012.00456.x ABSTRACT This article highlights the ability of airborne laser scanning (ALS) to detect, map and quantify geomorphological processes in high alpine environments. Since 2001, ALS measurements have been carried out regularly at Hintereisferner (Ötztal Alps, Tyrol, Austria), resulting in a unique data record of 18 ALS flight campaigns. The quantifications of volumetric earth surface changes caused by dead-ice melting, fluvial erosion/deposition, rock-fall activity, gravitational displacements and permafrost degradation in glaciated, recently deglaciated and periglacial terrain is based on the analysis of ALS point clouds (vector data) to preserve the high quality of the data. We present inter-annual, annual and perennial trends of geomorpho-dynamically induced topographic changes. The most significant changes occurred at two dead ice bodies (−0.48 m and −0.24 m respectively per year). At a complex rock fall site, mean annual vertical changes of −0.25 m are observed in the source area, respectively 0.25 m of deposited material in the run-out area. Fluvial erosion processes are connected with subsequent gravitational denudation, reallocation and deposition. Topographic changes caused by fluvial erosion between 2001 and 2009 range from −0.68 m to −1.20 m. Surface elevation increase caused by fluvial accumulation is found to be 0.48 m from 2001 to 2009. Minor annual surface elevation changes (between −0.05 m and −0.10 m a−1) are detected in permafrost areas. Finally, the significance of the process-dependent topographic change rates is assessed, regarding the accuracy of the ALS data, the magnitude of the process, the time lapse between the single ALS-campaigns and disturbing factors (e.g. snow cover). For processes with high magnitudes time lapse rates can be shorter than one year and disturbing factors have only minor influences on the results. In contrast, results of processes with low magnitudes gain relevance with an increasing time lapse between the ALS campaigns, the frequency of flight campaigns and if disturbing factors can be excluded. [ABSTRACT FROM AUTHOR]

New data technologies and modelling methods have gained more attention in the field of periglacial geomorphology during the last decade. In this paper we present a new modelling approach that integrates topographical, ground and remote sensing information in predictive geomorphological mapping using generalized additive modelling (GAM). First, we explored the roles of different environmental variable groups in determining the occurrence of non-sorted and sorted patterned ground in a fell region of 100 km2 at the resolution of 1 ha in northern Finland. Second, we compared the predictive accuracy of ground-topography- and remote-sensing-based models. The results indicate that non-sorted patterned ground is more common at lower altitudes where the ground moisture and vegetation abundance is relatively high, whereas sorted patterned ground is dominant at higher altitudes with relatively high slope angle and sparse vegetation cover. All modelling results were from good to excellent in model evaluation data using the area under the curve (AUC) values, derived from receiver operating characteristic (ROC) plots. Generally, models built with remotely sensed data were better than ground-topography-based models and combination of all environmental variables improved the predictive ability of the models. This paper confirms the potential utility of remote sensing information for modelling patterned ground distribution in subarctic landscapes. [ABSTRACT FROM AUTHOR]

Recent research has identified problems inherent in the identification and description of landforms. Morphologically similar small-scale glacial and periglacial landforms can be misinterpreted, thus hindering environmental reconstruction. This study reveals that a landform resembling a moraine at Stígárjökull, southern Iceland, is the product of both glacial deposition and mass movement. The landform has two distinct morphological and sedimentological components: a basal, lithologically diverse component, and an upper, lithologically homogenous component. Clast lithological analysis, particle shape and particle size measurements demonstrate that the basal component of the landform consists of sediment whose characteristics match nearby moraines. In contrast, the source of the upper component is a narrow outcrop of rock above the valley floor. Evidence suggests that frost-shattered material was transported across a perennial snow patch to a small moraine, leading to growth of the ‘moraine’. This combination of processes is unlikely to be unique, but the geological peculiarities of the field site permitted their identification. It is possible that many similar ‘moraines’ could be enlarged by subaerial feeding, leading to false reconstruction of glacier form and/or associated rates of erosion and sedimentation. Such polygenetic landform genesis therefore has implications for environmental reconstruction. [ABSTRACT FROM AUTHOR]