Geomorphologic equifinality: A comparison between shore platforms in Höga Kusten and Fårö, Sweden and the Vale of Glamorgan, South Wales, UK

Abstract

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.