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Studies on the formation of alpine lateral moraines are rare; consequently, their internal structure and their modes of formation are relatively poorly understood. We present here sedimentological and ground-penetrating radar (GPR) data from a lateral moraine complex where an exposure allows radar facies to be compared to the field evidence. The moraine, which is slightly asymmetric with a slightly steeper distal slope, consists of alternating clast- and matrix-supported stratified diamicts and intercalated sorted sediment units which are all subparallel to the moraine surface. They are interpreted as subaerial debris flows and fluvial sediments, respectively. The GPR, using frequencies of 50, 100 and 200 MHz, allows tracing of very similar subparallel reflectors to c. 10 m into the subsurface. These are interpreted to represent the diamict units while the thickness of the sorted sediment units is below GPR resolution. Our data suggests that a two or three frequency approach supplemented by common-midpoint (CMP) measurements works well in glaciated high-mountain environments. Based on our sedimentological and GPR data we develop a conceptual framework for the formation of successive lateral moraines which involves ice-contact fan sedimentation, followed by collapse and incremental reworking of the proximal side during glacier retreat.

Debris deposition by avalanches was monitored for six years at the Arnspitze south slope in the North-Tyrolean Limestone Alps. The slope investigated was deforested by a severe wildfire event in 1946 and is still largely vegetation-free today. We collected avalanche-transported debris on the snow fields at the base of the slope after ground avalanches in spring. The results show mean sediment yields of 126 t km-2 a-1; the mean erosion rate is 48 mm ka-1 for bedrock or 70 mm ka-1 for soil/debris, respectively. These values are much higher than most previous measurements reported in the literature. Avalanche erosion is extremely variable between the years, ranging from 0 t to 215 t per year. The thickness of the snow cover, the timing of the spring melt, debris storage in the preceding years and unknown random factors appear to be responsible for the temporal variations. There are also large spatial differences between the sub-catchments. The highest absolute removal (in tonnes) occurs in the largest catchments; the correlation between catchment size and removal rate (tonnes per unit size) is positive but weak. The investigations indicate that process equilibrium remains disturbed, even after more than 60 years have elapsed.

Catastrophic deterioration of limestone facades occurs where areas of stonework become rapidly hollowed out. It affects many historic buildings in Oxford, especially where soot-rich gypsum crusts have accumulated. In order to understand the processes of catastrophic deterioration we need to understand the microenvironmental conditions, especially the moisture distributions in the deteriorating walls. Geoelectric methods, in the form of two-dimensional (2D) resistivity surveys, have been used to study the distribution and amount of water stored in deteriorating limestone walls within the historic centre of Oxford. Fifteen vertical profiles, each 2–2.5 m in length, have been monitored at five sites using 50 medical electrodes and GeoTom equipment. Calculated moisture contents and distributions are presented for those profiles that extend up to 40 cm into the wall. The data indicate the diversity and complexity of moisture distributions within these often heterogeneous walls, which have also had long histories of decay and conservation. Replacement stone patches show consistently higher moisture conditions than the surrounding stone. Most profiles indicate the presence of wetter patches 5–10 cm behind the wall face under blackened crusts. Catastrophically decayed sections of profiles often exhibit wetter near-surface conditions than surrounding stonework, whilst areas with shallow but active decay are often much drier than surrounding crusted stone. In conclusion, the results give preliminary confirmation of a simple model of catastrophic decay and illustrate the complexity of moisture regimes in historic walls.