A mountain of fossils
Monte San Giorgio
|(CH 1903)||E 717620||N 83220||H 580.0|
|(WGS 84)||Long. 8.954||Lat. 45.890|
Stratigraphie, Sedimentology, Paleontology
Geo-mining, Hydromorphologie, Karst morphology
Naturalistic, Landscape, Didactic, Hiking
The paleontological wealth of the period between 242 and 235 million years ago is such that it has even earned the designation of the entire district of Mount San Giorgio as a UNESCO World Heritage Site. For the past 150 years, Mount San Giorgio has been the focus of research in the field of paleontology. Historically, the stratigraphic level of excavations is that of the Besano Formation, also called the Bituminous Zone Limit or, in German, Grenzbitumenzone. This is defined as a succession of sedimentary strata which contains an alternation of dolomite, volcanic tuff and bituminous schist formed from the remains of the rich fauna which inhabited the surface sea water of a basin, all arising as a result of the influx of the sea which characterizes the Middle Triassic Period. The isolated situation which the basin was in during the period between the Anisic and Ladinian Stages severely restricted the rate of sedimentation, so that the bodies fallen to the bottom accumulated, resulting in the formation of rock. Consequentially, circulation was restricted within the enclosed basin. This led to a scant replacement of water at the bottom of the sea, resulting in long periods without oxygen (i.e. a completely anoxic environment), thus excluding any necrophagic organisms. These conditions therefore guaranteed a perfect preservation of the skeletons which lay on the seabed. Reptiles, fish and invertebrates have been discovered in large quantities and varieties in just 16 metres of strata in the Besano Formation. Other types of fossils such as insects, plants and microfossils are rather more rare, which is why nowadays the research conducted by the Cantonal Museum of Natural History of Lugano has led to the carrying out of new excavations in the upper levels of the Saint Giorgio Dolomites and the Limestones of Meride.
Along the A2, take exit 52 Varese-Mendrisio-Stabio and head towards Varese-Stabio for about 1 kilometre, turning towards Genestrerio-Novazzano-Rancate-Arzo. Follow the signs for Arzo, reached by passing through the villages of Rancate and Besazio. From Arzo turn right towards Meride and continue for 1 kilometre.
Between Meride and Serpiano you can follow various paths which lead into the geological site.
ANTONIETTI A. et al. (1978): Sentiero naturalistico del Monte San Giorgio. Guida, commento e note. Ente ticinese per il turismo. Bellinzona. 163 pp.
COTTI G. et al. (1990): Introduzione al paesaggio naturale del Cantone Ticino.Vol. 1, Le componenti naturali, Bellinzona, 484 pp.
DECUYPER H. & ANTOGNINI M. (2008): Magie di pietra. Locarno. Armando Dadò.
FELBER M. & TINTORI A. (2011): Geoguida del Monte San Giorgio. Geologia insubrica.