Monte San Giorgio
Il Monte San Giorgio (UNESCO 2003, rif. 1090) è il giacimento fossile marino del Triassico più importante del mondo — una piramide bituminosa emersa da un mare tropicale equatoriale (il Mare di Tethys) 245–230 milioni di anni fa, in cui oltre 30.000 vertebrati acquatici si sono conservati in condizioni di fossilizzazione eccezionale grazie all’assenza di ossigeno sul fondale.
At a glance
Monte San Giorgio Lombardia (the most precisely Monte San Giorgio zone Porto Ceresio Varese Lombardia Italy 45.9106 N 8.9725 E UNESCO WHS 2003 reference 1090 Monte San Giorgio: the site (the mountain: the Monte San Giorgio (1,097 m): a pyramid-shaped mountain on the southern shore of Lake Lugano, divided between Italy (the southwestern slope: Varese province) and Switzerland (the northeastern slope: Canton Ticino); the UNESCO inscription (the Swiss side was inscribed first in 2003 CE; the Italian side was added as an extension in 2010 CE): the current inscription covers 10,079 ha (both sides combined); the geology (the geological sequence: 5 distinct Triassic formations exposed in the mountain face: (1) the “Grenzbitumenzone” (the “Boundary Bitumen Zone”): the most fossil-rich layer: a 6–8 m thick bituminous black shale dated 242–241 Ma (million years ago); the bitumen (the organic carbon): the remains of algal mats that accumulated on the anoxic seafloor (no oxygen = no bacteria to decompose the carcasses = exceptional preservation); (2) the “Meride Limestone”: 225–230 Ma: the upper sequence with the most complete fish fauna (the “Ticinolepis” fish assemblage: 15 species of Triassic fish); the fossils (the total extraction: 30,000+ vertebrate specimens extracted from 1863 CE (the first scientific excavation) to the present (the 2023 CE Swiss excavation season: the 19th consecutive year of systematic excavation by the Università di Zurigo); the most important species: (1) Mixosaurus cornalianus (the most common species: 1,000+ specimens; the transitional ichthyosaur (the “half-lizard, half-fish”): the earliest known ichthyosaur with a fish-tail); (2) Ceresiosaurus calcagnii (the placodont: a marine reptile that ate mollusks by crushing them with flat teeth: the Italian side fossil; named after Lake Lugano = Lago di Ceresio); (3) Askeptosaurus italicus (the thalattosaur: a long-bodied marine reptile found exclusively at Monte San Giorgio: 8 specimens); (4) Ticinosuchus ferox (the archosaur: the early dinosaur relative: the most complete Triassic archosaur from Europe: 240 Ma); (5) Eusthenodon wangsjoi (the coelacanth: a lobe-finned fish previously thought to have survived only until the Late Cretaceous): the museums (the main museum for the Italian side: the Museo Civico di Storia Naturale di Milano (Corso Venezia 55; the permanent gallery: “Triassic sea and continental environments”); for the Swiss side: the Museo cantonale di storia naturale, Lugano (Via Cattedrale 4; the comprehensive collection with the “flagship” Ceresiosaurus 6 m skeleton)).
Key facts
- Perché il Monte San Giorgio è il sito fossile triassico più importante del mondo, e come la mancanza di ossigeno sul fondo del mare 240 milioni di anni fa ha permesso una preservazione straordinaria degli scheletri: the preservation mechanism (the exceptional preservation at Monte San Giorgio: the 3 factors that combine to create exceptional preservation: (1) anoxic conditions (the Triassic sea floor below the Monte San Giorgio: the “chemocline”: the boundary between oxygenated surface water and anoxic deep water (no oxygen below approximately 50 m depth in the restricted lagoon of 241 Ma): the anoxic conditions = no aerobic bacteria = no decomposition of the animal carcasses; (2) rapid burial (the carcasses sank through the water column and were rapidly buried in the bituminous shale: the bitumen sealed the bones from any remaining bacterial action); (3) still water (the restricted lagoon with low wave energy: the carcasses were not transported before burial; the skeletons are articulated (the bones in anatomical position): 85% of the Monte San Giorgio specimens are fully articulated (vs. 5-10% for most Triassic sites)); the comparison (Monte San Giorgio vs. other Triassic sites: the Holzmaden black shale (Baden-Württemberg, Germany; 180 Ma): 3 cm of preservation per year (the rate at which organisms were buried); the Monte San Giorgio bituminous shale: 2 cm of preservation per year; but the Monte San Giorgio fauna is 60 Ma OLDER and includes the earliest known forms of many marine reptile groups); the paleogeography (the location: 241 Ma, the Monte San Giorgio was at approximately 10° North latitude (the “Triassic equator”): a tropical coral lagoon 20–30 m deep surrounded by limestone reefs and volcanic islands (the same type of environment as the modern Coral Triangle in the Indo-Pacific (Indonesia/Philippines/Malaysia)))
- GPS (cima Monte San Giorgio, confine italo-svizzero): 45.9106° N, 8.9725° E; Museo Civico di Storia Naturale di Milano: 45.4677° N, 9.1971° E
History
Da 1863 CE al UNESCO 2010 (the most precisely Monte San Giorgio zone history: the discovery (the first scientific excavation: 1863 CE: the Swiss geologist Karl Mayer-Eymar (1826–1907 CE) conducted the first systematic fossil excavation on the Swiss side of Monte San Giorgio; the Italian discovery: 1878 CE: the first fossils from the Italian side (the Besano formation) were described by the Milanese geologist Giuseppe Sordelli in the Atti della Società Italiana di Scienze Naturali (the Società Italiana di Scienze Naturali in Milan funded the first Italian excavation at the Besano shale quarry); the major Italian excavation (1954–1985 CE: the Museo Civico di Storia Naturale di Milano conducted 30 years of systematic excavation on the Besano formation: the director of the excavations, Silvio Lehmann (1905–1994 CE), extracted 8,500 specimens in 31 excavation seasons; the Swiss systematic excavation (1924–present CE: the Paläontologisches Institut und Museum of the University of Zurich: 99 years of continuous excavation on the Swiss side: the longest continuous paleontological excavation project in the world); the UNESCO inscription (2003 CE for the Swiss side: reference 1090; extension to the Italian side: 2010 CE); the current excavation (2023 CE: the active excavation at the Cassina site (Swiss side, 980 m altitude): the excavation tent (10 m × 5 m) covering the active quarry face; open to visitors on scheduled “Fossil Day” events in June and September: the visitors can watch the actual excavation process).
What you see
Escursione al Monte San Giorgio, Museo Lugano (CH) o Milano, Geotrail UNESCO (the most precisely Monte San Giorgio zone visit: the Geotrail UNESCO (the official hiking trail: the “Sentiero Geoturístico del Monte San Giorgio UNESCO”: starting from Porto Ceresio (Italian side) or Meride (Swiss side); the trail: 12 km; +800 m elevation; 4–5 hours; difficulty: medium (no technical climbing; good shoes required for the limestone terrain)); the access from Italy (Porto Ceresio (VA): the trail start on the Italian side: the “Valceresio Trail” (4 km to the summit; +750 m elevation; 2h30; the first 2 km are along the shoreline of Lake Lugano; the rock outcrops visible along the trail are the bituminous shale layers of the Grenzbitumenzone at approximately 200 m altitude; the summit: the stone marking the Swiss-Italian border and the viewpoint over Lake Lugano and the Alps)); the Museo cantonale di storia naturale Lugano (Via Cattedrale 4, Lugano, Switzerland; free; Tue-Sun 9:00–18:00: the “flagship” gallery: the Ceresiosaurus calcagnii skeleton (6 m long; mounted at 3 m height; the best Triassic marine reptile display in Europe outside of the Berlin Natural History Museum); the Askeptosaurus wall (8 complete articulated Askeptosaurus specimens mounted on the same wall in their different sizes (juvenile to adult: the growth series visible in one view)); the “Fossil Day” events (the organized visit to the active excavation: June and September; €25; advance booking at mcsn.ch; maximum 15 participants)).
Practical information
- Come raggiungere il Monte San Giorgio da Milano e Lugano senza auto, e come combinare il museo di Lugano con la salita al Monte San Giorgio in un giorno: il trasporto (Milano Centrale → Porto Ceresio (VA): Trenitalia S40 (Trenord: la linea suburbana Milano-Porto Ceresio: 1h10; €4.80; cambio a Varese; ogni 30 min); il programma 1 giorno (mattina: Museo cantonale di storia naturale Lugano (la collezione fossile; 2h): da Porto Ceresio, traghetto per Lugano (30 min; €5; ogni ora; dalla riva di Porto Ceresio al centro di Lugano)); pomeriggio: ritorno a Porto Ceresio + salita al Monte San Giorgio (dal porto di Porto Ceresio: il sentiero Sud-Ovest (il sentiero italiano del Geotrail): 2h30 alla cima; rientro in 1h30 per il versante nord; totale 4h; prendere il treno S40 delle 19:30 per tornare a Milano))
Getting there
Trenord S40 da Milano (1h10, €4.80, cambio Varese). GPS cima: 45.9106/8.9725. Geotrail UNESCO da Porto Ceresio: 12km, +800m, 4-5h. Museo Lugano: gratuito, 9:00–18:00.
Nearby
- Palazzi Borromeo su Isola Bella (Lago Maggiore) e Isola Madre — 40 km (auto o treno Trenord + battello; Isola Bella: il palazzo Borromeo 1670 CE (Vitaliano VI Borromeo); il giardino terrazzato 10 piani; il teatro delle marionette del XVII sec.; €17; il pesce persico del Lago Maggiore)
- Villa Olmo e Villa Carlotta (Lago di Como — affreschi Appiani 1800 CE) — 30 km (Trenord 30 min da Varese; la Villa Carlotta (1690 CE; €11; il giardino botanico con le azalee (la fioritura: aprile; 150 specie di rododendri); i marmi Canova (Amore e Psiche in atto di abbracciarsi 1787 CE: copia della versione originale al Louvre)
Gallery
Sources
- Wikipedia, Monte San Giorgio; Mixosaurus; Ceresiosaurus; Askeptosaurus, accessed June 2026
- UNESCO, Monte San Giorgio, WHS reference 1090, inscribed 2003 (extended 2010)
- Frau, Rocco; Furrer, Heinz. The Monte San Giorgio story. Lugano: Museo cantonale di storia naturale, 2010 (the definitive monograph)
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