Monte San Giorgiois a Swiss mountain andUNESCO World Heritage Sitenear theborderbetweenSwitzerlandandItaly.It is part of theLugano Prealps,overlookingLake Luganoin the SwissCantonofTicino.
| Monte San Giorgio | |
|---|---|
 Monte San Giorgio (right), amongLake LuganoandMonte Generoso(left, background) | |
| Highest point | |
| Elevation | 1,097 m (3,599 ft) |
| Prominence | 758 m (2,487 ft)[1] |
| Coordinates | 45°54′49″N8°56′59″E/ 45.91361°N 8.94972°E |
| Geography | |
  Monte San Giorgio Location in Switzerland  Monte San Giorgio Monte San Giorgio (Switzerland)  Monte San Giorgio Monte San Giorgio (Lombardy)  Monte San Giorgio Monte San Giorgio (Italy) | |
| Location | Ticino,Switzerland |
| Parent range | Lugano Prealps |
| Topo map | Swisstopo1373 Mendrisio |
| Climbing | |
| Easiest route | Trail |
| Official name | Monte San Giorgio |
| Type | Natural |
| Criteria | viii |
| Designated | 2003(27thsession) |
| Reference no. | 1090 |
| Region | Europe and North America |
| Extensions | 2010 |
Monte San Giorgio is a wooded mountain, rising to 1,097 m (3,600 feet) above sea level. It has a roughly pyramidal shape, with a steep north edge sloping towards Lake Lugano and a more shallow South Slope extending towards thePo Plain.The eastern (Swiss) side of the mountain, between the municipalities ofBrusino Arsizio,Riva San Vitale,andMeride,was listed as a World Heritage Site in 2003. This was in recognition of its cultural, biological, and especially paleontological significance. The site is renowned for its fossil content, one of the best known records of marine life in the MiddleTriassicperiod.[2][3][4]The Italian region west ofPoncione d'Arzo(Porto Ceresio) was added as an extension to the World Heritage Site in 2010.[5]
History and cultural heritage
editHumans have inhabited Monte San Giorgio at least since the area's equivalent of theNeolithic Period,around 6,000 years ago. The south side of the mountain is home toTremona-Castello Archaeological Park,a fortress and settlement which was continuously inhabited by artisans from the Neolithic up until the14th century.Artifacts, architecture, and other evidence ofRomanandmedievalactivity are abundant on and around the mountain. Productivelimestonequarries were active during this period and beyond in Italy (ViggiùandSaltrio) and Switzerland (Arzo).[3][5]
Fossil and oil exploitation
editThe mountain's fossil fuel deposits were exploited more recently. Motivated by a search for furnace and lamp oil forMilan,mining projects attempted to establish themselves in the late 18th and early 19th centuries, focusing on thebituminousshaleof theGrenzbitumenzone(Besano Formation). Though these early efforts did not last very long, exploitation of the Grenzbitumenzone ramped up in the early 20th century once its pharmaceutical properties were discovered. In 1908, the Spinirolo plant was built for the purpose of processing the shale into saurol, anichthyol-like skin ointment. Saurol production and mining continued until the 1950s, and operations went bankrupt in 1960. Minerals such asbarite,fluorite,andgalenawere also prospected on the mountain during the 20th century.[3][5][4]
ItalianpaleontologistGiulio Curionifirst mentioned that fossils were present on the mountain in 1847. The first paper focusing on Monte San Giorgio fossils in particular was published byEmilio Cornaliain 1854. Small excavations by Milanese paleontological societies in 1863 and 1878 provided more specific context on the paleontology of Monte San Giorgio. Shale extraction brought the fossil deposits to the attention ofUniversity of ZurichpaleontologistBernhard Peyerin 1919. Peyer and his associates began a series of large and systematic excavations in 1924, greatly expanding both the number of known fossil sites and the number of geological layers known to preserve fossils. Peyer's excavations continued until 1938, discovering many new species of fossil animals in the process. World War II paused both Saurol production and fossil collection. TheMuseo Civico di Storia Naturale di Milano(Milan Civic Museum of Natural History, MSNM) was bombed in 1943, destroying its collection of Monte San Giorgio specimens. Fossil excavations resumed in 1950 under the helm ofEmil Kuhn-Schnyder,Peyer's successor and former student. Kuhn-Schnyder established thePalaeontological Institute and Museum of the University of Zurich(PIMUZ) in 1956, which now hosts over 15,000 specimens of Monte San Giorgio fossils. Collection campaigns have continued intermittently up until the present day, managed by the MSNM,University of Milan(UNIMI), and theMuseo Cantonale di Storia Naturale di Lugano(Cantonal Museum of Natural History, MCSN). Over 21,000 fossil specimens have been collected in total by 2010.[3][5][4]
UNESCO listing
editIn 2003, the Monte San Giorgio was listed as a UNESCO World Heritage Site, with 849 ha (hectares) of protected land from the Swiss communes ofMeride,Brusino Arsizio,andRiva San Vitale.This protected area was surrounded by a 1389 ha buffer zone overlapping six additional communes. The nomination of Monte San Giorgio was inspired by its exceptional paleontological value, with multiple fossiliferous levels preserving among the best records of Middle Triassic life in the world. Monte San Giorgio also presents a link between local geology and culture, as well as unique ecological heritage relative to the rest of Switzerland.[3]
In 2010, the World Heritage Site was expanded further, adding 240.34 ha of land from the Italian communes ofBesano,Porto Ceresio,and Viggiù. These communes, alongsideClivioand Saltrio, were also included within an 1818.45 ha Italian buffer zone. This additional land brings the total area of UNESCO protected property to 1089.34 ha and the total buffer zone area to 3207.45 ha. Inclusion of the Italian territory was motivated for its paleontological heritage.[5]
Each side of the site is managed by separate Swiss and Italian organizations, as well as a transnational board which moderates between the management organizations. The site is not in any particular danger from overutilization or degradation, so management is mainly related to closely-regulated fossil excavations, promotion, and maintenance of low-impact tourism facilities. Monte San Giorgio fossils are collected, curated, and displayed by a small number of museums, primarily the PIMUZ, MSNM, and MCSN. Local museums in Besano, Meride, andInduno Olonaalso play a role in promotion of the site and its fossils. TheMuseo dei fossili del Monte San Giorgio(Museum of fossils from Monte San Giorgio) in Meride was first opened 1973, receiving a 2012 redesign and expansion courtesy of TicinesearchitectMario Botta.[5]
Geology
editThe geological layers of Monte San Giorgio span more than 100 million years, from thePermiantoJurassicperiods. The rocks forming the mountaindipsouthwards, with older rocks exposed as one travels north and younger rocks exposed as one travels south. The oldest rocks are Permianvolcanicbasementmaterial on the mountain's steep north slope. These are followed byTriassicsedimentsandcarbonatesat higher elevations on the mountain.Middle Triassiclayers are the most fossiliferous and extraordinary from a global perspective, and are encompassed by the protected area north of Meride. South of Meride, they are replaced byLate Triassiccoastal sediments which give way toEarly Jurassiclimestoneoverlooking the Po Plain.[5]
Permian volcanics and Triassic transgression
editThestratigraphicallylowest rocks exposed on Monte San Giorgio areLower Permianin age, around 290-280Ma(million years old). They are remnants of early rifting and volcanic activity in the aftermath of theVariscan orogeny.These volcanic rocks are mainly reddishrhyoliteandandesitewith aporphyritictexture, produce large crystals of quartz, barite, and fluorite.[6][4]The Permian basement rocks are terminated by anunconformity,an erosional surface succeeded by Triassic sediments.
These following Triassic sediments aresiliciclasticand terrestrial in origin, mainlysandstoneandconglomerateeroded from the underlying volcanic material. "Servino"is the name given to older sediments from theEarly Triassic(about 252-247 Ma). Slightly younger sediments from the lateAnisian(the first stage of the Middle Triassic, 247-242 Ma) are called theBellano Formation.The Servino and Bellano Formation can be difficult to differentiate, but together they reconstruct a period oftransgression(rising sea levels) encroaching onto a sandy coastline dotted withdeltasandfloodplains.[7][8][9][10][4]
As the Anisian stage continued, the coastal sandstone of the Bellano Formation was replaced withcalcareousmarine deposits. These were the first of many massivecarbonate platformsbuilding up on a branch of theTethys Seawhich was expanding westwards. The shallow carbonate platform of Monte San Giorgio and surrounding areas is known as the Salvatore platform, which is now preserved as theSan Salvatore Dolomite.It reconstructs a warm, tropical environment, with the most common fossils belonging to algae and shelledinvertebrates.Only the lower portion of the San Salvatore Dolomite is preserved on Monte San Giorgio, corresponding to a particularly shallow andsalineperiod in the history of the platform.Stromatolitesand otheralgal laminationsare generally the only fossils found in the Lower Salvatore Dolomite.[7][11]
Grenzbitumenzone / Besano Formation
editNear the end of the Anisian, the southern edge of the Salvatore platform deepens abruptly, giving way to a more sterile basin developed between carbonate platforms. The basin is now preserved as a relatively narrow band of dark dolomite and shale, running east to west along the edge of Monte San Giorgio. This formation has been called the Besano Formation (in Italy) or the Grenzbitumenzone (in Switzerland). It represents the first of several sections on the mountain enriched with well-preserved fossils. The Grenzbitumenzone, especially its shale layers, is enriched with organic material derived fromcyanobacteria.This accumulation of organic material presumably made the bottom of the basinanoxicor dysoxic, with low oxygen levels in the seawater. The only fossils of seabed-living organisms belong toDaonella,a thin-shelledbivalveadapted to low oxygen. Fossils of free-swimming animals are more diverse, with marinereptiles,fish, and shelledcephalopodsbeing the most prominent. Terrestrial and shallow-water organisms such asshrimps,coniferbranches (Voltzia), and land reptiles (Ticinosuchus) were occasionally washed into the basin as well.[7][12][4][5]
Meride Limestone
editThe basin responsible for the Grenzbitumenzone continued to persist through the Ladinian, though the Grenzbitumenzone itself transitioned into a less fossiliferous formation known as theSan Giorgio Dolomite.This formation has lower organic content, no shale, and only a few fragmentary fossils. Higher organic content and finer laminations return a short while later, forming the lower part of the fossil-richMeride Limestone.The Meride Limestone probably represents a period of increased instability on the growing carbonate platforms, sending surges of carbonate grains into the basin. Skeletons tend to be even better preserved than in the Grenzbitumenzone, suggesting that the basin deepened further or acquired extensive microbial mats. A section of dolomite, the "Dolomitband", forms the top of the Lower Meride Limestone. It also marks the start of the Upper Meride Limestone, which is similar to the lower part of the formation but has only a few fossiliferous sections. The Upper Meride Limestone eventually becomes dominated by very finely-laminated marls and shales with increased clay content. This clay-rich interval, indicative of increased terrestrial runoff within the shrinking basin, is known as the "Kalkschieferzone".[7]
Late Triassic
editBy the beginning of the Late Triassic, a majormarine regression(sea level fall) threatened the fossil-rich basin and carbonate system of the Middle Triassic. During theCarnian(around 237 to 227 Ma), the first stage of the Late Triassic, carbonate platforms were replaced by shallow-water and coastal sediments. This formation, thePizzella Marls,is diagnosed by a higher amount ofsiliciclastics(sediments eroded down from terrestrial rocks) andevaporites(mineral deposits from dried water), such asgypsum.[13]In the succeedingNorianstage (around 227 to ~208 Ma), carbonate platforms and rising sea levels were renewed with vigor, depositing a massive expanse of carbonate known as theDolomia Principaleor Hauptdolomit.[14]The Dolomia Principale is a brittle, crystalline rock mass which was fractured bynormal faultsnot long after it was first formed. This is an early pulse of an overallextensionaltectonic regime, a period of rifting which would eventually break upPangea.By the time of theRhaetianstage (~208 to 201 Ma), the Dolomia Principale was buried by a shorter but more stable sequence of shallow-watermarland carbonate, theTremona Series.[15][16]
Early Jurassic
editRifting continued into theEarly Jurassic,alongside marine sedimentation. From theHettangiantoPliensbachianstages (201 to 183 Ma), the area reacquired a deeper basinal environment. These basin sediments are preserved as theMoltrasio Limestone,a thick sheet ofmicrite(fine-grained limestone) with abundantchertyandmarlybeds created byturbidites(mudslides). Jurassic sediments are preserved to the east, south, and west of Monte San Giorgio; the position of the modern mountain would have been an island or shallow environment during the Jurassic. Its Jurassic sediments are now eroded away to reveal older Triassic and Permian rocks. Conversely,Monte Generoso,immediately to the east of Monte San Giorgio, is composed mostly of Jurassic basinal sediments. Outcrops of Jurassic sediments are also seen close to the Po Plain, at the south edge of Monte San Giorgio (in a broad sense).[17][16]The productive "marble"quarries found south of Monte San Giorgio actually mined non-metamorphosedlimestone, rather than true marble. These limestone units were formed at the same general time as the Moltrasio Limestone.
Ecological heritage
editThefaunaandfloraof Monte San Giorgio are diverse, with some species found nowhere else in Switzerland. The prevailing ecosystems aremixed broadleaf forestsandmeadowsinfluenced by the mountain'ssub-Mediterranean climate.Monte San Giorgio is one of the southernmost areas of Switzerland, with mild winters, high humidity, and many hours of sunshine. Due to the variation in underlying geology, bothacidicandalkalinesoilsare developed, supporting different vegetation communities. Therhyolite-based northern slope is mostly covered byCastanea sativa(sweet chestnut),Quercus petraea(sessile oak), andFraxinus excelsior(European ash). Thedolomite-based southern slope is more diverse in its plant life and soil quality, with common plants includingCarpinus betulus(common hornbeam),Ostrya carpinifolia(European hop-hornbeam),Tilia(linden),Asperula taurina,Quercus pubescens(pubescent oak), andFraxinus ornus(manna ash).[3]
The driest and most alkaline soils of Monte San Giorgio are home to the Ticino dry meadows, a unique biome with over 100 plant and species, 38 of which are rare or endangered within Switzerland.Carex humilis(dwarf sedge) andMolinia caerulea arundinacea(tall moor grass) are the most commongrasses,while Monte San Giorgio supports the few Swiss populations ofwildflowerssuch asAdenophora liliifolia,Gladiolus imbricatus,Iris graminea,Lotus herbaceus,andDanthonia alpina.[3]
102 species ofvertebratesare found on Monte San Giorgio, 37 of which are endangered in Switzerland. The mountain is the only Swiss stronghold forMicrotus savii(Savi's pine vole), and hosts breeding sites foramphibianssuch asBufo bufo(common toad),Rana temporaria(common frog),Rana dalmatina(agile frog),Hyla intermedia(Italian tree frog), and other species. Invertebrates are even more diverse, including some species which are very rare in Switzerland, such asPyrgus armoricanus(Oberthur's grizzled skipper),Euchorthippus declivus(Jersey grasshopper), andPholidoptera littoralis insubrica(littoral dark bush-cricket). The dry meadows are especially diverse, hosting several species of previously undiscovered or undocumentedspiders.Isolated populations ofcrustaceansandmillipedesinhabit the deep karst and cave systems found on the mountain. Monte San Giorgio is considered a "mycologicalwonder ", with over 500 species offungi,several of which are endemic.[3]
References
edit- ^Swisstopomap
- ^Monte San Giorgio – UNESCO World Heritage Centre
- ^abcdefgh"Nomination of Monte San Giorgio for inclusion in the World Heritage List"(PDF).UNESCO World Heritage Centre.2003.
- ^abcdefRieppel, Olivier (2019).Mesozoic Sea Dragons: Triassic Marine Life from the Ancient Tropical Lagoon of Monte San Giorgio.Bloomington, IN:Indiana University Press.ISBN978-0-253-04013-8.
- ^abcdefgh"Nomination of Monte San Giorgio (Italian extension of Monte San Giorgio, Switzerland, inscribed in 2003) for inscription on the UNESCO World Heritage List"(PDF).UNESCO World Heritage Centre.2010.
- ^Beltrán-Triviño, Alejandro; Winkler, Wilfried; von Quadt, Albrecht; Gallhofer, Daniela (2016)."Triassic magmatism on the transition from Variscan to Alpine cycles: evidence from U–Pb, Hf, and geochemistry of detrital minerals".Swiss Journal of Geosciences.109(3): 309–328.doi:10.1007/s00015-016-0234-3.ISSN1661-8734.S2CID133145459.
- ^abcdBernasconi, Stefano Michele (1991).Geochemical and microbial controls on dolomite formation and organic matter production/preservation in anoxic environments: a case study from the Middle Triassic Grenzbitumenzone, Southern Alps (Ticino, Switzerland).ETH Zurich Dissertation(Doctoral Thesis). pp. 1–198.doi:10.3929/ethz-a-000611458.hdl:20.500.11850/140499.
- ^Sommaruga, A.; Hochuli, P.A.; Mosar, J. (1997). "The Middle Triassic (Anisian) conglomerates from Capo San Martino, South of Lugano-Paradiso (Southern Alps, Switzerland)".Geologia Insubrica.2(1): 1–14.
- ^Sciunnach, Dario; Gaetani, Maurizio; Roghi, Guido (2015)."La successione terrigena pre-Ladinica tra Lugano e Varese (Canton Ticino, Svizzera; Lombardia, Italia)".Geologia Insubrica(in Italian).11(1): 45–61.
- ^RENESTO, SILVIO; STOCKAR, RUDOLF (2018-09-05)."FIRST RECORD OF A COELACANTH FISH FROM THE MIDDLE TRIASSIC MERIDE LIMESTONE OF MONTE SAN GIORGIO (CANTON TICINO, SWITZERLAND)".Rivista Italiana di Paleontologia e Stratigrafia (Research in Paleontology and Stratigraphy).124:No 3 (2018).doi:10.13130/2039-4942/10771.
- ^Stockar, Rudolf (2010-07-01)."Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina beds (Meride Limestone, Monte San Giorgio, Switzerland)".Swiss Journal of Geosciences.103(1): 101–119.doi:10.1007/s00015-010-0008-2.ISSN1661-8734.S2CID129454913.
- ^Etter, Walter (2002). "Monte San Giorgio: remarkable Triassic marine vertebrates". In Bottjer, D.J.; Etter, W.; Hagadorn, J.W.; Tang, C.M. (eds.).Exceptional fossil preservation; a unique view on the evolution of marine life.New York: Columbia University Press. pp. 220–242.
- ^Furrer, Heinz (1995)."The Kalkschieferzone (Upper Meride Limestone, Ladinian) near Meride (Canton Ticino, Southern Switzerland) and the evolution of a Middle Triassic intraplatform basin".Eclogae Geologicae Helvetiae.88(3): 827–852.
- ^Meister, Patrick; Mckenzie, Judith A.; Bernasconi, Stefano M.; Brack, Peter (2013)."Dolomite formation in the shallow seas of the Alpine Triassic".Sedimentology.60(1): 270–291.doi:10.1111/sed.12001.ISSN1365-3091.S2CID140597765.
- ^Neuweiler, Fritz; Bernoulli, Daniel (2005-02-01)."Mesozoic (Lower Jurassic) red stromatactis limestones from the Southern Alps (Arzo, Switzerland): calcite mineral authigenesis and syneresis-type deformation".International Journal of Earth Sciences.94(1): 130–146.doi:10.1007/s00531-004-0442-3.ISSN1437-3262.S2CID140164600.
- ^abBerra, Fabrizio; Galli, Maria Teresa; Reghellin, Federico; Torricelli, Stefano; Fantoni, Roberto (2009-05-18)."Stratigraphic evolution of the Triassic–Jurassic succession in the Western Southern Alps (Italy): the record of the two‐stage rifting on the distal passive margin of Adria".Basin Research.21(3): 335–353.doi:10.1111/j.1365-2117.2008.00384.x.hdl:2434/48580.ISSN1365-2117.S2CID128904701.
- ^Schöllhorn, Iris; Adatte, Thierry; Charbonnier, Guillaume; Mattioli, Emanuela; Spangenberg, Jorge E.; Föllmi, Karl B. (2020-08-01)."Pliensbachian environmental perturbations and their potential link with volcanic activity: Swiss and British geochemical records".Sedimentary Geology.406:105665.doi:10.1016/j.sedgeo.2020.105665.ISSN0037-0738.S2CID219746317.
External links
edit
Media related toMonte San Giorgio (Prealpi Luganesi)at Wikimedia Commons- Monte San Giorgio on Hikr
- World Heritage official website
- Museum of fossils from Monte San Giorgioin Meride
- World heritage site of Monte San Giorgio
