Monte San Giorgio
Monte San Giorgio | |
---|---|
Highest point | |
Elevation | 1,097 m (3,599 ft) |
Prominence | 758 m (2,487 ft)[1] |
Isolation | 3.38 km (2.10 mi) |
Coordinates | 45°54′49″N 8°56′59″E / 45.91361°N 8.94972°E |
Geography | |
Location | Ticino, Switzerland |
Parent range | Lugano Prealps |
Topo map | Swisstopo 1373 Mendrisio |
Climbing | |
Easiest route | Trail |
Europe and North America | |
Extensions | 2010 |
Monte San Giorgio is a Swiss mountain and UNESCO World Heritage Site near the border between Switzerland and Italy. It is part of the Lugano Prealps, overlooking Lake Lugano in the Swiss Canton of Ticino.
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 the
History and cultural heritage
Humans have inhabited Monte San Giorgio at least since the area's equivalent of the Neolithic Period, around 6,000 years ago. The south side of the mountain is home to Tremona-Castello Archaeological Park, a fortress and settlement which was continuously inhabited by artisans from the Neolithic up until the 14th century. Artifacts, architecture, and other evidence of Roman and medieval activity are abundant on and around the mountain. Productive limestone quarries were active during this period and beyond in Italy (Viggiù and Saltrio) and Switzerland (Arzo).[3][5]
Fossil and oil exploitation
The mountain's fossil fuel deposits were exploited more recently. Motivated by a search for furnace and lamp oil for
Italian
UNESCO listing
In 2003, the Monte San Giorgio was listed as a UNESCO World Heritage Site, with 849 ha (hectares) of protected land from the Swiss communes of Meride, Brusino Arsizio, and Riva 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 of Besano, Porto Ceresio, and Viggiù. These communes, alongside Clivio and 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, and Induno Olona also play a role in promotion of the site and its fossils. The Museo 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 Ticinese architect Mario Botta.[5]
Geology
The geological layers of Monte San Giorgio span more than 100 million years, from the
Permian volcanics and Triassic transgression
The
These following Triassic sediments are siliciclastic and terrestrial in origin, mainly sandstone and conglomerate eroded from the underlying volcanic material. "Servino" is the name given to older sediments from the Early Triassic (about 252-247 Ma). Slightly younger sediments from the late Anisian (the first stage of the Middle Triassic, 247-242 Ma) are called the Bellano Formation. The Servino and Bellano Formation can be difficult to differentiate, but together they reconstruct a period of transgression (rising sea levels) encroaching onto a sandy coastline dotted with deltas and floodplains.[7][8][9][10][4]
As the Anisian stage continued, the coastal sandstone of the Bellano Formation was replaced with
Grenzbitumenzone / Besano Formation
Near 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 from cyanobacteria. This accumulation of organic material presumably made the bottom of the basin anoxic or dysoxic, with low oxygen levels in the seawater. The only fossils of seabed-living organisms belong to Daonella, a thin-shelled bivalve adapted to low oxygen. Fossils of free-swimming animals are more diverse, with marine reptiles, fish, and shelled cephalopods being the most prominent. Terrestrial and shallow-water organisms such as shrimps, conifer branches (Voltzia), and land reptiles (Ticinosuchus) were occasionally washed into the basin as well.[7][12][4][5]
Meride Limestone
The basin responsible for the Grenzbitumenzone continued to persist through the Ladinian, though the Grenzbitumenzone itself transitioned into a less fossiliferous formation known as the San 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-rich Meride 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
By the beginning of the Late Triassic, a major
Early Jurassic
Rifting continued into the Early Jurassic, alongside marine sedimentation. From the Hettangian to Pliensbachian stages (201 to 183 Ma), the area reacquired a deeper basinal environment. These basin sediments are preserved as the Moltrasio Limestone, a thick sheet of micrite (fine-grained limestone) with abundant cherty and marly beds created by turbidites (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-metamorphosed limestone, rather than true marble. These limestone units were formed at the same general time as the Moltrasio Limestone.
Ecological heritage
The fauna and flora of Monte San Giorgio are diverse, with some species found nowhere else in Switzerland. The prevailing ecosystems are mixed broadleaf forests and meadows influenced by the mountain's sub-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, both acidic and alkaline soils are developed, supporting different vegetation communities. The rhyolite-based northern slope is mostly covered by Castanea sativa (sweet chestnut), Quercus petraea (sessile oak), and Fraxinus excelsior (European ash). The dolomite-based southern slope is more diverse in its plant life and soil quality, with common plants including Carpinus betulus (common hornbeam), Ostrya carpinifolia (European hop-hornbeam), Tilia (linden), Asperula taurina, Quercus pubescens (pubescent oak), and Fraxinus 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.
102 species of
References
- ^ Swisstopo map
- ^ Monte San Giorgio – UNESCO World Heritage Centre
- ^ a b c d e f g h "Nomination of Monte San Giorgio for inclusion in the World Heritage List" (PDF). UNESCO World Heritage Centre. 2003.
- ^ ISBN 978-0-253-04013-8.
- ^ a b c d e f g h "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.
- S2CID 133145459.
- ^ .
- ^ 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.
- .
- S2CID 129454913.
- ^ 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.
- S2CID 140597765.
- S2CID 140164600.
- ^ S2CID 128904701.
- S2CID 219746317.
External links
- Media related to Monte San Giorgio (Prealpi Luganesi) at Wikimedia Commons
- Monte San Giorgio on Hikr
- World Heritage official website
- Museum of fossils from Monte San Giorgio in Meride
- World heritage site of Monte San Giorgio