Discussion of ‘A5 Llyn Ogwen peatslide, Capel Curig, North Wales’ by D. Nichol, G.K. Doherty & M.J. Scott, Quarterly Journal of Engineering Geology and Hydrogeology, 40, 293–299

A.P. Dykes & J. Warburton write: Nichol et al . (2007) present an interesting case study of a small shallow landslide that occurred in North Wales in November 2005. They describe the landslide and its local context in sufficient detail to conclude that it was caused by the combination of high rainfall and subsurface hydrological controls. They also conclude that a bio-engineering approach to remediation of the affected slope is necessary to protect the highway and will provide the most appropriate solution given the environmental sensitivity of the site. Although we agree fully with the general conclusions as inferred from the information presented, we feel that it would be beneficial to provide a broader context for this study in terms of recent research into peat instability on hillslopes. The purpose of this discussion is therefore to comment on some of the details provided in the study and, in doing so, to highlight some of the problems and misconceptions often associated with the study of peat landslides. Nichol et al . (2007) begin by stating that ‘Peatslides are relatively uncommon in the UK’ and that ‘as far as can be determined, this is the first example of a natural peatslide event to be documented for Wales’. The latter comment is probably true, as we have not yet verified the reportedly similar event in January 2005 that affected the A470 road 45–50 km south of Llyn Ogwen (Mason 2005). However, peat landslides are perhaps more common in the UK than is often realized. Of all the recorded global peat mass movements, around 20% have occurred in mainland Britain (i.e. excluding Northern Ireland) and 60% in Ireland (Northern Ireland and the Republic of Ireland combined). Over 50 separate landslides involving blanket bog are known from Northern Ireland and at least 35 in northern England …