Comparison of geological aspects

One of the exceptional values on which the nomination is based is the fact that the Dolomites document a significant interval of the Earth’s history, from the Upper Permian through to the end of the Mesozoic. The most important interval of the succession is represented by Permian and Triassic rocks. Since this interval of time is well represented in other sites, comparison both with localities already included in the WHL and with other areas is necessary.

Comparison with properties already on the World Heritage List

The first comparison with already-inscribed sites considers the example of Monte San Giorgio site in Switzerland, because this is a part of the same structural and paleogeographic context of the Dolomites. The site is on the WHL for its exceptional marine vertebrate fauna of the Ladinian period (Middle Triassic), found in intra-platform lagoons located on the western side of the Triassic Tethian Ocean. The quantity and quality of the fossils present at Monte S. Giorgio are certainly more relevant than the marine vertebrate findings found in the Dolomites. The latter, however, preserves spectacularly the original palaeogeography of Mesozoic seas and islands, allowing the immediate visualization and understanding of the ancient environment where these large reptiles lived. Furthermore the Swiss site represents only the Ladinian stage, a shorter time interval when compared with the Dolomites, where the whole Mesozoic Era is represent with a comparable richness of information for a twenty times-longer time period. The Triassic is represented in continental facies in the Ischigualasto Provincial Park-Talampaya National Park (Argentina) where a succession of vertebrate fauna and fossil flora are superbly documented. Here the comparison is more complex, since the site is included on the list only from the viewpoint of fossiliferous documentation. Many intervals where it is possible to analyze the continental flora and fauna are also present in the Dolomites. In fact, remains of terrestrial vertebrates have been found at several levels, and the discovery of important groups of fossil footprints is important for the study of the evolution of reptiles and dinosaurs. The peculiarity of the Dolomites is that these fossiliferous levels that document the terrestrial environments can be linked physically and/or by biostratigraphy with the marine successions, and are therefore easier to outline in a bio- and chronostratigraphic context. The best-represented intervals are the Lower Triassic and the Anisian ones (the latter have no match elsewhere), but also the Late Triassic (Carnian) and the base of the Norian are well documented. In the Dolomites area there is also the most important Upper Permian site preserving tetrapods footprints (the Bletterbach/Butterloch section, Rio delle Foglie). The uniqueness of the site is enhanced by its closeness with several other footprints sites that offer an enlarged vision spanning from the Permian up to the Lower Jurassic (e.g. the Lavini di Marco site). The Argentine succession is exclusively continental, so it represents palaeoenvironments that are sensitively different from the Dolomites. For this reason, the two sites then may eventually be considered as complementary for the Triassic Period. A more extensive time interval, and therefore with more common elements, is documented in the site in Dorset and on the East Devon Coast, which through a series of separate sections along the south coast of Great Britain allows for the reconstruction of a more or less continuous succession of the whole Mesozoic. The Triassic in the Dorset area is represented by about 1,100 meters of sandstone and limestone in prevalently continental facies (the so-called “Germanic facies”) whereas the marine facies are only appears at the summit. But there are enormous differences between this succession and that of the Dolomites, since the Triassic is prevalently marine in the latter, represented by more than 3,500 meters of sediments deposited in a tropical environment, documenting both sedimentation and physiography of the Triassic Tethian Ocean. As regards the Jurassic, the Dorset/East Devon Coast offers one of the most complete basin successions in the world, with at least 74 biozones with ammonites. In the Dolomites, the Jurassic is distinguished instead by the presence of carbonate platforms and adjacent basins, which give fauna and ammonoids comparable to those of the English site only locally. The different and exceptional aspect of the Dolomites Jurassic is, however, the possibility of documenting the evolution of these platforms, and their response to climatic and tectonic forcing. In particular, during the Jurassic the shallow flooding of the carbonate sedimentation areas with encrinites and Rosso Ammonitico facies, is documented. Also for the Cretaceous, the stratigraphic succession of the Dorset/East Devon Coast is very different from that of the Dolomites, which is prevalently emipelagic and deep. Therefore, the comparison with the two areas is not simple, since both demonstrate the response of the depositional systems to the development of a passive continental margin, but from completely different paleogeographical positions.