Monte San Giorgio
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Monte San Giorgio is a mountain and
UNESCO World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...
on the border between
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
and
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
. It is part of the
Lugano Prealps The Lugano Prealps (''Prealpi Luganesi'' or ''Prealpi Lombarde Occidentali'' in Italian) are a mountain range in the western part of the Alps. They are located in Canton Ticino (southern Switzerland) and in Lombardy (northern Italy). Geography ...
, overlooking
Lake Lugano __NOTOC__ Lake Lugano ( it, Lago di Lugano or , from la, Ceresius lacus; lmo, Lagh de Lugan) is a glacial lake which is situated on the border between southern Switzerland and northern Italy. The lake, named after the city of Lugano, is situated ...
in the Swiss Canton of
Ticino Ticino (), sometimes Tessin (), officially the Republic and Canton of Ticino or less formally the Canton of Ticino,, informally ''Canton Ticino'' ; lmo, Canton Tesin ; german: Kanton Tessin ; french: Canton du Tessin ; rm, Chantun dal Tessin . ...
. 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
Po Plain The Po Valley, Po Plain, Plain of the Po, or Padan Plain ( it, Pianura Padana , or ''Val Padana'') is a major geographical feature of Northern Italy. It extends approximately in an east-west direction, with an area of including its Venetic ex ...
. The eastern (Swiss) side of the mountain, between the municipalities of
Brusino Arsizio Brusino Arsizio is a municipality in the district of Lugano in the canton of Ticino in Switzerland on the Lake of Lugano. History The village has been inhabited since the Roman era. In 1970, a plundered Roman grave was found with grave goods. Th ...
,
Riva San Vitale Riva San Vitale is a municipality in the canton of Ticino in Switzerland, located in the district of Mendrisio. History Riva San Vitale is first mentioned in 774 as ''Primo Sobenno''. In 1115 it was mentioned as ''Ripa Sancti Vitalis''. The a ...
, and
Meride Meride is a village and former municipality in the district of Mendrisio in the canton of Ticino in Switzerland. On 14 April 2013 the former municipalities of Besazio, Ligornetto and Meride merged into the municipality of Mendrisio.
, 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 Middle
Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
period. The Italian region west of Poncione d'Arzo (
Porto Ceresio Porto Ceresio ( Varesino: ''Pòrt Cerési'') is a ''comune'' (municipality) on Lake Lugano in the Province of Varese in the Italian region Lombardy, located about northwest of Milan and about northeast of Varese, on the border with Switzerlan ...
) was added as an extension to the World Heritage Site in 2010.


History and cultural heritage

Humans have inhabited Monte San Giorgio at least since the area's equivalent of the
Neolithic Period The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several parts ...
, 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 As a means of recording the passage of time, the 14th century was a century lasting from 1 January 1301 ( MCCCI), to 31 December 1400 ( MCD). It is estimated that the century witnessed the death of more than 45 million lives from political and n ...
. Artifacts, architecture, and other evidence of
Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a letter ...
and
medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the Post-classical, post-classical period of World history (field), global history. It began with t ...
activity are abundant on and around the mountain. Productive
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
quarries were active during this period and beyond in Italy (
Viggiù Viggiù (;  lmo, Vigiǘu, label= Varesino ) is a ''comune'' (municipality) in the Province of Varese in the Italian region Lombardy, located about northwest of Milan and about northeast of Varese, on the border with Switzerland. Viggiù borders ...
and
Saltrio Saltrio is a ''comune'' (municipality) in the Province of Varese in the Italian region Lombardy, located about northwest of Milan and about northeast of Varese, on the border with Switzerland. As of 31 December 2004, it had a population of 2,925 ...
) and Switzerland (
Arzo Arzo was a municipality in the district of Mendrisio in the canton of Ticino in Switzerland. It had an area of and a population of 1,126 inhabitants (December 2007). On 5 April 2009 the municipalities of Arzo, Capolago, Genestrerio, Mendris ...
).


Fossil and oil exploitation

The mountain's fossil fuel deposits were exploited more recently. Motivated by a search for furnace and lamp oil for
Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
, mining projects attempted to establish themselves in the late 18th and early 19th centuries, focusing on the
bituminous Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
of the
Grenzbitumenzone The Besano Formation is a geological formation in the southern Alps of northwestern Italy and southern Switzerland. This formation, a short but fossiliferous succession of dolomite and black shale, is famous for its preservation of Middle Triassic ...
(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, an
ichthyol Ammonium bituminosulfonate or ammonium bituminosulphonate (synonyms of ichthammol, CAS# brand name: Ichthyol) is a product of natural origin obtained in the first step by dry distillation of sulfur-rich oil shale (bituminous schists). By sulfonat ...
-like skin ointment. Saurol production and mining continued until the 1950s, and operations went bankrupt in 1960. Minerals such as
barite Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...
,
fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...
, and
galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cryst ...
were also prospected on the mountain during the 20th century. Italian
paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Giulio Curioni first mentioned that fossils were present on the mountain in 1847. The first paper focusing on Monte San Giorgio fossils in particular was published by
Emilio Cornalia Emilio Cornalia (25 August 1824 – 8 June 1882) was an Italian naturalist. Treccani. He was born in Milan and died in the same city. He was conservator from 1851 to 1866, and director from 1866 till his death, of the Milan Museum of Natural H ...
in 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 of
University of Zurich The University of Zürich (UZH, german: Universität Zürich) is a public research university located in the city of Zürich, Switzerland. It is the largest university in Switzerland, with its 28,000 enrolled students. It was founded in 1833 f ...
paleontologist
Bernhard Peyer Bernhard Peyer (25 July 1885 – 23 February 1963) was a Swiss paleontologist and anatomist who served as a professor at the University of Zurich. A major contribution was on the evolution of vertebrate teeth. Peyer was born in Schaffhausen, Switze ...
in 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. The
Museo Civico di Storia Naturale di Milano The Museo Civico di Storia Naturale di Milano (Milan Natural History Museum) is a museum in Milan, Italy. It was founded in 1838 when naturalist Giuseppe de Cristoforis donated his collections to the city. Its first director was Giorgio Jan. ...
(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 of Emil Kuhn-Schnyder, Peyer's successor and former student. Kuhn-Schnyder established the Palaeontological 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 The University of Milan ( it, Università degli Studi di Milano; la, Universitas Studiorum Mediolanensis), known colloquially as UniMi or Statale, is a public research university in Milan, Italy. It is one of the largest universities in Europe ...
(UNIMI), and the Museo Cantonale di Storia Naturale di Lugano (Cantonal Museum of Natural History, MCSN). Over 21,000 fossil specimens have been collected in total by 2010.


UNESCO listing

In 2003, the Swiss side of Monte San Giorgio was listed as a UNESCO World Heritage Site, with 849 ha (
hectare The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is a ...
s) of protected land from the communes of
Meride Meride is a village and former municipality in the district of Mendrisio in the canton of Ticino in Switzerland. On 14 April 2013 the former municipalities of Besazio, Ligornetto and Meride merged into the municipality of Mendrisio.
,
Brusino Arsizio Brusino Arsizio is a municipality in the district of Lugano in the canton of Ticino in Switzerland on the Lake of Lugano. History The village has been inhabited since the Roman era. In 1970, a plundered Roman grave was found with grave goods. Th ...
, and
Riva San Vitale Riva San Vitale is a municipality in the canton of Ticino in Switzerland, located in the district of Mendrisio. History Riva San Vitale is first mentioned in 774 as ''Primo Sobenno''. In 1115 it was mentioned as ''Ripa Sancti Vitalis''. The a ...
. 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. In 2010, the World Heritage Site was expanded further, adding 240.34 ha of land from the Italian communes of
Besano Besano is a town and ''comune'' located in the province of Varese, in the Lombardy region of northern Italy. Paleontological site The fossils of Besano In 1993 the fossil of a Triassic aquatic reptile dating back to about 235 million years ...
,
Porto Ceresio Porto Ceresio ( Varesino: ''Pòrt Cerési'') is a ''comune'' (municipality) on Lake Lugano in the Province of Varese in the Italian region Lombardy, located about northwest of Milan and about northeast of Varese, on the border with Switzerlan ...
, and Viggiù. These communes, alongside
Clivio Clivio is a ''comune'' (municipality) in the Province of Varese in the Italian region Lombardy, located about northwest of Milan and about northeast of Varese, on the border with Switzerland. As of 31 December 2004, it had a population of 2,010 a ...
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 portion of the mountain was motivated by the same paleontological heritage as the Swiss portion. Its history of paleontological study and economic exploitation is significantly older than the equivalent Swiss portion of the mountain. Moreover, the Italian side has unique geological qualities, such as a denser assortment of fish fossils and
stratigraphy Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks. Stratigrap ...
which is more easily traced over a wide area. 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 Induno Olona is a town and ''comune'' in Italy, in north-western Lombardy, north of Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after R ...
also play a role in promotion of the site and its fossils. Th
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 An architect is a person who plans, designs and oversees the construction of buildings. To practice architecture means to provide services in connection with the design of buildings and the space within the site surrounding the buildings that h ...
Mario Botta Mario Botta (born 1 April 1943) is a Swiss architect. Career Botta designed his first building, a two-family house at Morbio Superiore in Ticino, at age 16. He graduated from the Università Iuav di Venezia (1969). While the arrangements of spa ...
.


Geology

The geological layers of Monte San Giorgio span more than 100 million years, from the
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
to
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
periods. The rocks forming the mountain dip southwards, with older rocks exposed as one travels north and younger rocks exposed as one travels south. The oldest rocks are Permian
volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...
basement A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, ...
material on the mountain's steep north slope. These are followed by
Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
s and
carbonates A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...
at higher elevations on the mountain.
Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...
layers 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 by
Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...
coastal sediments which give way to
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
overlooking the Po Plain.


Permian volcanics and Triassic transgression

The stratigraphically lowest rocks exposed on Monte San Giorgio are
Lower Permian The Cisuralian is the first series/epoch of the Permian. The Cisuralian was preceded by the Pennsylvanian and followed by the Guadalupian. The Cisuralian Epoch is named after the western slopes of the Ural Mountains in Russia and Kazakhstan an ...
in age, around 290-280 Ma (million years old). They are remnants of early rifting and volcanic activity in the aftermath of the
Variscan orogeny The Variscan or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. Nomenclature The name ''Variscan'', comes f ...
. These volcanic rocks are mainly reddish
rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
and
andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomi ...
with a
porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all ...
texture, produce large crystals of quartz, barite, and fluorite. The Permian basement rocks are terminated by an
unconformity An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...
, an erosional surface succeeded by Triassic sediments. These following Triassic sediments are
siliciclastic Siliciclastic (or ''siliclastic'') rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclasic rock types include mudrock, sandstone, and conglomerate Conglomera ...
and terrestrial in origin, mainly
sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...
and conglomerate eroded from the underlying volcanic material. " Servino" is the name given to older sediments from the
Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...
(about 252-247 Ma). Slightly younger sediments from the late
Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...
(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 A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarel ...
and
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
s. As the Anisian stage continued, the coastal sandstone of the Bellano Formation was replaced with
calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adje ...
marine deposits. These were the first of many massive
carbonate platform A carbonate platform is a sedimentary body which possesses topographic relief, and is composed of autochthonic calcareous deposits. Platform growth is mediated by sessile organisms whose skeletons build up the reef or by organisms (usually microb ...
s building up on a branch of the
Tethys Sea The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...
which 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 the
San Salvatore Dolomite The San Salvatore Dolomite, sometimes known as the Salvatore Dolomite or San Salvatore Formation, is a Middle Triassic (late Anisian) geological formation in Switzerland and Italy. The primarily lithology is micritic dolomite with a high proporti ...
. It reconstructs a warm, tropical environment, with the most common fossils belonging to algae and shelled
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s. Only the lower portion of the San Salvatore Dolomite is preserved on Monte San Giorgio, corresponding to a particularly shallow and saline period in the history of the platform.
Stromatolite Stromatolites () or stromatoliths () are layered sedimentary formations (microbialite) that are created mainly by photosynthetic microorganisms such as cyanobacteria, sulfate-reducing bacteria, and Pseudomonadota (formerly proteobacteria). The ...
s and other algal laminations are generally the only fossils found in the Lower Salvatore Dolomite.


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 The Besano Formation is a geological formation in the southern Alps of northwestern Italy and southern Switzerland. This formation, a short but fossiliferous succession of dolomite and black shale, is famous for its preservation of Middle Triassic ...
(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 Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...
. This accumulation of organic material presumably made the bottom of the basin
anoxic The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts: * Anoxic waters, sea water, fresh water or groundwater that are depleted of diss ...
or dysoxic, with low oxygen levels in the seawater. The only fossils of seabed-living organisms belong to ''
Daonella ''Daonella'' is a genus of oyster-like saltwater clams, marine bivalve mollusks which lived in the middle to late Triassic period. They are related to the genera '' Aparimella'' and '' Halobia''. Since they were ubiquitous in the Arctic, Tethy ...
'', a thin-shelled
bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
adapted to low oxygen. Fossils of free-swimming animals are more diverse, with marine
reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s, fish, and shelled
cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
s being the most prominent. Terrestrial and shallow-water organisms such as
shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
s,
conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...
branches ('' Voltzia''), and land reptiles (''
Ticinosuchus ''Ticinosuchus'' is an extinct genus of suchian archosaur from the Middle Triassic (Anisian - Ladinian) of Switzerland and Italy. Description One of only a handful of fossil reptiles that have been found in Switzerland, ''Ticinosuchus'' (mea ...
'') were occasionally washed into the basin as well.


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 Meride is a village and former municipality in the district of Mendrisio in the canton of Ticino in Switzerland. On 14 April 2013 the former municipalities of Besazio, Ligornetto and Meride merged into the municipality of Mendrisio.
. 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".


Late Triassic

By the beginning of the Late Triassic, a major
marine regression A marine regression is a geological process occurring when areas of submerged seafloor are exposed above the sea level. The opposite event, marine transgression, occurs when flooding from the sea covers previously-exposed land. Evidence of marine ...
(sea level fall) threatened the fossil-rich basin and carbonate system of the Middle Triassic. During the
Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by t ...
(around 237 to 227 Ma), the first stage of the Late Triassic, carbonate platforms were replaced by shallow-water and coastal sediments. This formation, the Pizzella Marls, is diagnosed by a higher amount of
siliciclastic Siliciclastic (or ''siliclastic'') rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclasic rock types include mudrock, sandstone, and conglomerate Conglomera ...
s (sediments eroded down from terrestrial rocks) and
evaporite An evaporite () is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocea ...
s (mineral deposits from dried water), such as
gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...
. In the succeeding
Norian The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic defi ...
stage (around 227 to ~208 Ma), carbonate platforms and rising sea levels were renewed with vigor, depositing a massive expanse of carbonate known as the Dolomia Principale or Hauptdolomit. The Dolomia Principale is a brittle, crystalline rock mass which was fractured by
normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...
s not long after it was first formed. This is an early pulse of an overall
extensional In any of several fields of study that treat the use of signs — for example, in linguistics Linguistics is the science, scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, obj ...
tectonic regime, a period of rifting which would eventually break up
Pangea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...
. By the time of the
Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...
stage (~208 to 201 Ma), the Dolomia Principale was buried by a shorter but more stable sequence of shallow-water
marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...
and carbonate, the Tremona Series.


Early Jurassic

Rifting continued into the
Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
, alongside marine sedimentation. From the
Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (My ...
to
Pliensbachian The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 190.8 ± 1.5 Ma and 182.7 ± 1.5 Ma (million years ago). The Plien ...
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 Micrite is a limestone constituent formed of calcareous particles ranging in diameter up to four μm formed by the recrystallization of lime mud. Flügel, Erik, ''Microfacies of Carbonate Rocks: Analysis, Interpretation and Application,'' Springe ...
(fine-grained limestone) with abundant
chert Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a prec ...
y and
marl Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part o ...
y beds created by
turbidite A turbidite is the geologic deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean. Sequencing Turbidites were ...
s (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 Monte Generoso (also known as ''Calvagione'') is a mountain of the Lugano Prealps, located on the border between Switzerland and Italy and between Lake Lugano and Lake Como. The western and southern flanks of the mountain lie in the Swiss cant ...
, 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). The productive "
marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or Dolomite (mineral), dolomite. Marble is typically not Foliation (geology), foliated (layered), although there are exceptions. In geology, the ...
" quarries found south of Monte San Giorgio actually mined non-
metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
limestone, rather than true marble. These limestone units were formed at the same general time as the Moltrasio Limestone.


Ecological heritage

The
fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoo ...
and
flora Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous) native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' gut flora'' or '' skin flora''. E ...
of Monte San Giorgio are diverse, with some species found nowhere else in Switzerland. The prevailing ecosystems are mixed broadleaf forests and
meadow A meadow ( ) is an open habitat, or field, vegetated by grasses, herbs, and other non-woody plants. Trees or shrubs may sparsely populate meadows, as long as these areas maintain an open character. Meadows may be naturally occurring or artifi ...
s 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 In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
and
alkaline In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
s are developed, supporting different vegetation communities. The
rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...
-based northern slope is mostly covered by ''
Castanea sativa ''Castanea sativa'', the sweet chestnut, Spanish chestnut or just chestnut, is a species of tree in the family Fagaceae, native to Southern Europe and Asia Minor, and widely cultivated throughout the temperate world. A substantial, long-lived ...
'' (sweet chestnut), ''
Quercus petraea ''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emble ...
'' (sessile oak), and ''
Fraxinus excelsior ''Fraxinus excelsior'', known as the ash, or European ash or common ash to distinguish it from other types of ash, is a flowering plant species in the olive family Oleaceae. It is native throughout mainland Europe east to the Caucasus and Albor ...
'' (European ash). The
dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...
-based southern slope is more diverse in its plant life and soil quality, with common plants including '' Carpinus betulus'' (common hornbeam), ''
Ostrya carpinifolia ''Ostrya carpinifolia'', the European hop-hornbeam, is a tree in the family Betulaceae. It is the only species of the genus ''Ostrya'' that is native to Europe. The specific epithet ''carpinifolia'' means "hornbeam-leaved", from , the Latin word ...
'' (European hop-hornbeam), ''
Tilia ''Tilia'' is a genus of about 30 species of trees or bushes, native throughout most of the temperateness, temperate Northern Hemisphere. The tree is known as linden for the European species, and basswood for North American species. In Britain a ...
'' (linden), '' Asperula taurina'', ''
Quercus pubescens ''Quercus pubescens'', the downy oak or pubescent oak, is a species of white oak (genus ''Quercus'' sect. ''Quercus'') native to southern Europe and southwest Asia, from northern Spain (Pyrenees) east to the Crimea and the Caucasus. It is also fou ...
'' (pubescent oak), and ''
Fraxinus ornus ''Fraxinus'' (), commonly called ash, is a genus of flowering plants in the olive and lilac family, Oleaceae. It contains 45–65 species of usually medium to large trees, mostly deciduous, though a number of subtropical species are evergr ...
'' (manna ash). 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) and '' Molinia caerulea arundinacea'' (tall moor grass) are the most common
grasses Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns and ...
, while Monte San Giorgio supports the few Swiss populations of
wildflower A wildflower (or wild flower) is a flower that grows in the wild, meaning it was not intentionally seeded or planted. The term implies that the plant probably is neither a hybrid nor a selected cultivar that is in any way different from the w ...
s such as ''
Adenophora liliifolia ''Adenophora liliifolia'' is a species of plants belonging to the family Campanulaceae. It is native to Europe and Northern America. Synonyms: * ''Adenophora lilifolia'' (L.) Ledeb. ex A.DC. References

{{Authority control Campanuloide ...
'', '' Gladiolus imbricatus'', '' Iris graminea'', '' Lotus herbaceus'', and ''
Danthonia alpina ''Danthonia'' is a genus of Eurasian, North African, and American plants in the grass family. Members of this genus are sometimes referred to as oatgrass, but that common name is not restricted to this genus. Other common names include heathgrass ...
''. 102 species of
vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s are found on Monte San Giorgio, 37 of which are endangered in Switzerland. The mountain is the only Swiss stronghold for '' Microtus savii'' (Savi's pine vole), and hosts breeding sites for
amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
s such as ''
Bufo bufo The common toad, European toad, or in Anglophone parts of Europe, simply the toad (''Bufo bufo'', from Latin ''bufo'' "toad"), is a frog found throughout most of Europe (with the exception of Ireland, Iceland, and some Mediterranean islands), in ...
'' (common toad), ''
Rana temporaria The common frog or grass frog (''Rana temporaria''), also known as the European common frog, European common brown frog, European grass frog, European Holarctic true frog, European pond frog or European brown frog, is a semi-aquatic amphibian ...
'' (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 as '' Pyrgus armoricanus'' (Oberthur's grizzled skipper), '' Euchorthippus declivus'' (Jersey grasshopper), and '' Pholidoptera littoralis insubrica'' (littoral dark bush-cricket). The dry meadows are especially diverse, hosting several species of previously undiscovered or undocumented
spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s. Isolated populations of
crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s and
millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a resu ...
s inhabit the deep karst and cave systems found on the mountain. Monte San Giorgio is considered a "
mycological Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans, including as a source for tinder, traditional medicine, food, and entheogens, as w ...
wonder", with over 500 species of
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
, several of which are endemic.


References


External links

*
Monte San Giorgio on HikrWorld Heritage official website
in Meride
World heritage site of Monte San Giorgio
{{DEFAULTSORT:San Giorgio World Heritage Sites in Switzerland World Heritage Sites in Italy San Giorgio San Giorgio Mountains of Ticino One-thousanders of Switzerland