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This study uses results from a series of analogue models, and field observations, scanned data and sections of natural landslides to investigate the kinematics and internal deformation during the failure of an unstable slope. The models simulate collapse of granular slopes and focus on the spatial and temporal distribution of their internal structures. Using a series of systematically designed models, we have studied the effect of friction and deformability of the runout base on internal deformation within a granular slope. The results of these different models show that the collapse of granular slopes resulted in different-generation extensional faults at the back of the slope, and contractional structures (overturned folds, sheath folds and thrusts) at the toe of the slope. The failure surfaces and the volume of the failure mass changed both spatially and temporally. Younger failure surfaces formed in the back of the older ones by incorporating additional new material from the head of the slope. Our model results also show that the nature of the runout base has a significant influence on the runout distance, topography and internal deformation of a granular slope. Model results are compared with natural landslides where local profiles were dug in order to decipher the internal structures of the failure mass. The natural cases show similar structural distribution at the head and toe of the failure mass. As in model results, our field observations indicate the presence of at least two generations of failure surfaces where the older ones are steeper.

This paper presents a case study comparing shore platforms of the same lithology and different rock structures (limestone) with those of different lithologies but similar rock structures (limestone, dolerite) in Wales and Sweden. Results of this study illustrate that different erosion mechanisms (i.e. wave action and ice scour) produce similar erosion products and meso-scale (cm–m) landforms (i.e. stepped shore platforms) in structurally similar lithologies. In contrast, lithologically similar rocks (i.e. limestones) generate different meso-scale landforms and shore platform morphologies. Thus, structural controls appear to be more critical than lithological controls in generating meso-scale erosion products, such as rock blocks, in this comparative study. The similarities in the meso-scale geomorphology appear to be caused by uniform rock structure (i.e. rock hardness, joint density, spacing of bedding/horizontal jointing and the slope and direction of bedding/horizontal jointing in relation to the sea). Blocks produced by the jointing have been eroded by high energy waves in the case of Wales and drifting sea ice in the case of one of the Swedish sites. Meanwhile, different rock structures in a similar lithology (i.e. limestone) resulted in very different landforms, under the same environmental conditions as the previous example. As such, this research also provides observational evidence supporting the concept of equifinality.

Rock surface millimetre-scale roughness and weathering of supratidal Mallorcan carbonate coasts (Balearic Islands)