Geomorphological maps of Irish peat landslides created using hand-held GPS

Abstract

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Peat mass movements are relatively common geomorphological phenomena in the uplands of Ireland and parts of northern Britain. Geomorphological mapping of many peat landslides has led to the identification of different types of failures based on repeatedly occurring morphological and geometric characteristics. Furthermore, much of the recently enhanced understanding of mass failures in peat deposits, published in several recent reviews, has been obtained through detailed analysis of the geomorphological maps produced from the new field surveys that are herein presented together for the first time. The map that is the focus of this paper is a composite figure that shows geomorphological maps of the majority of extant bogow and bog slide types of peat mass movements in Ireland, together with two peat ows and a large peat slide that has not previously been described. The paper examines the methodology used to create the maps, and highlights the value of the maps in presenting potentially critical evidence that may not be discernible by field inspection alone. Creating geomorphological maps of peat landslides from field sketches provides highly satisfactory results if selected features are geo-referenced using a hand-held GPS at an average frequency of around once for every 30 m of source area perimeter or other linear component of a landslide. In the case of very large failures and very old and degraded failures, lower frequencies of GPS points can be tolerated because critical morphological evidence appears to scale-up with failure size and smaller-scale morphological details are lost with increasing failure age due to natural degradation of the disrupted peat.