The Geodiversity of the Dolomites
A specific and important characteristic of the Dolomites consists in their geodiversity. This concept first appeared in Australia (especially in Tasmania) in 1991 (Sharples, 1995), during an international congress on geoconservation, and received wide recognition, even if it was not always perfectly understood. This concept has not yet been properly developed in methodological terms and in the applied field. In addition, some examples in different geological contexts (latu sensu) are shown which pinpoint the complexity and, sometimes, the ambiguity of this term (Barthlott & al.,1996; Dixon, 1996; Eberhard, ed., 1997; Erikstad, 1999; Gray, 2004; Zwolinski, 2004; Piacente & Coratza, ed., 2005). Some definitions of geodiversity are here summarised. They underline the complexity and difficulties in defining this concept a priori and, in particular, in applying it (Panizza & Piacente, 2007).
- “intrinsic” geodiversity = on the basis of the geological complexity (l.s.) of the study area;
- “extrinsic” geodiversity = in relation to geological differences (l.s.) compared with other areas;
- “simpler” geodiversity = refers to the total range of geological objects (l.s.) in a given territory;
- “broader” geodiversity = refers to particular geosystems, that are in themselves diverse or complex;
- geodiversity assessed in a different way, according to the “scale” of analysis: global, regional or local;
- geodiversity with a “subjective” criterion, i.e. based on some specific geological objects (l.s.).
As regards the Dolomites, when considered on a global scale, they have specific geological, geomorphological and landscape characteristics which distinguish them from all other mountains in the world: i.e., they have greatly accentuated “extrinsic geodiversity” on a global level. Also on a regional level and in relation to morphostructural landforms, the Dolomites have a high degree of extrinsic geodiversity compared with other alpine mountains. This is particularly true with respect to morphotectodynamics (relief energy, fault scarps, morphoneotectonic evidence etc.), morphotectostatics (fault-line valleys, slopes more or less inclined according to the tectonic dip of strata, rock towers isolated by fracture lines etc.) and morpholithology (steep dolomite walls overlying mild slopes in arenaceous-clayey materials, terraces or steps in correspondence with particular rock types etc.). Furthermore, when observed all together, they are very complex stratigraphically (from the Permian to the Cretaceous), lithologically (prevalently dolostones, but also limestones, sandstones, porphyries, lavas, gypsum etc.) and geomorphologically (mostly climatic landforms: glacial, periglacial, fluvial etc., relict, dormant or active). Therefore, they also have greatly accentuated “intrinsic geodiversity” on a regional scale. Nevertheless, when the petrographic, stratigraphic and paleontological features of certain geological formations such as Dolomia Principale or San Cassiano Formation, are examined in detail, characteristics of accentuated uniformity (i.e. low intrinsic geodiversity) can be noticed in the whole Dolomite area. Moreover, the same uniformity is observed in certain types of landforms (talus cones and scree slopes). Therefore, for a certain typology of “geological objects” on a regional scale, these mountains show limited “intrinsic geodiversity”. On the contrary, if other categories of “geological objects” are taken into account, as, for example, landslides, they show, still on a regional scale, a considerable complexity of types, causes, ages, lithology, movement, extent etc.; that is they have greatly accentuated “intrinsic geodiversity”. Another example is offered by karst areas: they display in detail a vast array of landforms, that is, considerable intrinsic geodiversity on a local scale. These examples confirm that, although geodiversity is assumed as a basic principle for understanding and appraising geological (and geomorphological) heritage, the debate on its definition is still at an early stage and requires further contributions and reflections. Furthermore, whatever may be the specific meaning of this term, diverse geodiversity characteristics (Plate MP-1) lead to an integration of the concept of geoheritage. For all these reasons, the Dolomites can be considered as a high-altitude field laboratory for research, education and development of geological and geomorphological theories and understanding.