Concepts and terminology for the risk of degradation of geological heritage sites: fragility and natural vulnerability, a case study

This paper focuses on the conservation of geological heritage sites and specifically on the assessment of the risk of degradation. A review of the relevant literature shows (a) a lack of a standardised terminology used by different authors and (b) a lack of a standard methodology that supports the recognition and prevention of threats affecting a geosite. Three criteria (previous studies, the most common meaning of the words used and the use of terms in related disciplines) were used to select four terms with which to assess the risk of degradation: sensitivity, fragility, natural vulnerability and anthropic vulnerability. This paper provides a detailed description and discussion of these terms and their relevance. To test the use of these terms, an analysis of the fragility and natural vulnerability of geosites was performed in La Rioja (Spain), where more than one hundred outcrops bearing exceptional dinosaur footprints are located. The main factors that affect the fragility of these geosites are related to the lithology and to the location and typology of the ichnite. With respect to natural vulnerability, this study reveals several factors and processes that are involved in the degradation of these sites and establishes several field indicators that indicate deterioration. This research was intended to establish a common framework for specialists (both scientists and managers) working on geoconservation issues.