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57-592: The formation is a relatively thin band of dark dolomite and shale, approximately 5 to 16 metres (16 to 52 ft) in total thickness. It extends about 10 kilometres (6.2 mi) from east to west along the northern edge of Monte San Giorgio and across the Swiss-Italian border towards Besano. In individual outcrops, the Grenzbitumenzone overlies the lower part of San Salvatore Dolomite , a thick and widespread carbonate-rich formation. The later parts of

114-502: A decrease in benthic macroinvertebrate biomass, which lead to the disappearance of food sources into the substrate. Because the benthic system regulates energy in aquatic ecosystems, studies have been made of the mechanisms of the benthic zone in order to better understand the ecosystem. Benthic diatoms have been used by the European Union's Water Framework Directive (WFD) to establish ecological quality ratios that determined

171-541: A dysoxic environment, preservation may have been facilitated by bacterial mats, adhering and sealing a skeleton onto the substrate. However, direct evidence for bacterial mats is not present. Two ways to quantify a skeleton’s preservation are completeness (the proportion of a skeleton present in a fossil) and articulation (the proportion of a skeleton preserved in life position). The completeness and articulation of Serpianosaurus fossils are variable, though are fairly high on average. The two factors are most clearly linked in

228-692: A final stretch separating Val Müstair and the Engadin from Vinschgau , South Tyrol , terminating at the Austrian-Swiss-Italian tripoint just north of Piz Lad . Campione d'Italia is a comune of the Province of Como in the Lombardy region of Italy and an exclave surrounded by the Swiss canton of Ticino . At its closest, the exclave is less than one kilometre (0.6 mi) from

285-458: A stretch of the Melezza . It rises again to Pilone peak before descending to Lago Maggiore between Brissago and Cannobio , on the left bank making landfall at Caviano and passing west of Lugano and the villages of Malcantone to Ponte Tresa at Lake Lugano . It then forms the southernmost corner of Switzerland including Chiasso , turning north again outside of Como and now forming

342-660: A white color extend over a wide area. They have very little organic matter and instead contain shell fragments and peloids. This white dolomite likely represents distal turbidite deposits, collapsed from nearby carbonate sources. A similar origin is inferred for massive (unbedded) dolomite layers, which have a porous texture and heterogenous grain sizes. There is some evidence of reworking, as thin dolomite layers rarely show wavy layering or are ripped up into clasts by deep currents. The black shale layers occasionally preserve bands of chert , derived from radiolarian blooms. Numerous narrow bentonite layers ( volcanic tuffs ) occur throughout

399-475: Is a gently sloping benthic region that extends away from the land mass. At the continental shelf edge, usually about 200 metres (660 ft) deep, the gradient greatly increases and is known as the continental slope. The continental slope drops down to the deep sea floor. The deep-sea floor is called the abyssal plain and is usually about 4,000 metres (13,000 ft) deep. The ocean floor is not all flat but has submarine ridges and deep ocean trenches known as

456-533: Is no specific region of the body with significantly lower completeness, arguing that the fossils were unaffected by preferential scavenging. Fossil completeness may have been enhanced by the relatively small and isolated nature of the Grenzbitumenzone basin, protected from the influence of stronger marine currents. The actinopterygian fauna of the Besano Formation was described in detail by James Brough (1939) and Toni Bürgin (1992). The cephalopod fauna of

513-466: Is not easy to map or observe these organisms and their habitats, and most modern observations are made using remotely operated underwater vehicles (ROVs), and rarely submarines . Benthic macroinvertebrates have many important ecological functions, such as regulating the flow of materials and energy in river ecosystems through their food web linkages. Because of this correlation between flow of energy and nutrients, benthic macroinvertebrates have

570-635: Is not possible to reach the territory without crossing either Swiss territory or waters. On 1 January 2020, Campione and the Italian waters of Lake Lugano became part of the European Customs Union and a customs border crossing and check points were established. As of the December 2023 timetable change, cross-border services between Italy and Switzerland exist on the following railway lines (from West to East): There have been plans in

627-508: Is present but uncommon, likely a consequence of low iron availability. The organic matter can be characterized as type II kerogen , enriched in hopane and porphyrin compounds, though strongly depleted in Carbon-13 . These biomarkers , when combined, indicate that most of the organic material was derived from cyanobacteria . Other sediments and rock types are uncommon in the formation. Thin layers of fine-grained laminated dolomite with

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684-525: Is probably a result of subtle deep-water currents, during a long period of slow decay on the seabed. Heads and tails tend to curve in the same direction, which may be a consequence of current flow. Saurichthys fossils of the Grenzbitumenzone are often well-preserved, though disarticulated and twisted specimens are more common than in the Cassina beds of the Meride Limestone. This may be due to

741-672: Is recommended in the European Union benthic monitoring program (by Kelly 1998 for the United Kingdom then in the EU and for the EU as a whole by CEN 2003 and CEN 2004) and in some United States programs (by Moulton et al. 2002). Benthic gross primary production (GPP) may be important in maintaining biodiversity hotspots in littoral zones in large lake ecosystems . However, the relative contributions of benthic habitats within specific ecosystems are poorly explored and more research

798-572: Is separated from Valtellina by the border passing just north of Tirano , turning north again along Piz Paradisin , Munt Cotschen , Piz da l'Acqua to the inclusion of Livigno in Italy. The border now follows the southern watershed of Val Müstair , touching Piz Murtaröl , Piz Tea Fondada , Piz Schumbraida , Piz Umbrail until it reaches the pass road connecting Vinschgau with the Valtellina and Stilfserjoch . The border now turns north for

855-569: Is the ecological region at the lowest level of a body of water such as an ocean , lake , or stream , including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word βένθος ( bénthos ), meaning "the depths". Organisms living in this zone are called benthos and include microorganisms (e.g., bacteria and fungi ) as well as larger invertebrates , such as crustaceans and polychaetes . Organisms here generally live in close relationship with

912-527: Is the longest border of both Italy and of Switzerland . The border is a product of the Napoleonic period , established with the provisional constitution of the Helvetic Republic of 15 January 1798, restored in 1815. While this border existed as a border of Switzerland from 1815, there was only a unified Italian state to allow the existence of a "Swiss-Italian border" with the formation of

969-629: The European migrant crisis , the Swiss government cracked down on the practice, establishing more stringent controls in Swiss-bound trains and deploying helicopter and drone patrols. The government rejected calls to build a fence along the border. In April 2017, the Italian foreign ministry called the Swiss ambassador for "urgent talks" after Switzerland decided to close "three minor border crossings" at night. Benthic zone The benthic zone

1026-649: The Kingdom of Italy in 1861, it previously comprised the borders between Switzerland and the Kingdom of Sardinia , the Kingdom of Lombardy–Venetia and the province of Cisleithania of Austria-Hungary . There remained some territorial disputes after the formation of the Kingdom of Italy, resolved in the Convenzione tra l'Italia e la Svizzera per l'accertamento della frontiera fra la Lombardia ed il Cantone dei Grigioni of 1863. Other Swiss-Italian treaties regarding

1083-497: The hadal zone . For comparison, the pelagic zone is the descriptive term for the ecological region above the benthos, including the water column up to the surface. At the other end of the spectrum, benthos of the deep ocean includes the bottom levels of the oceanic abyssal zone . For information on animals that live in the deeper areas of the oceans see aphotic zone . Generally, these include life forms that tolerate cool temperatures and low oxygen levels, but this depends on

1140-466: The water column ; even within the benthic zone variations in such factors as light penetration, temperature and salinity give rise to distinct differences, delineated vertically, in the groups of organisms supported. Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column: the pressure difference can be very significant (approximately one atmosphere for each 10 meters of water depth). Many have adapted to live on

1197-510: The Besano Formation was described in detail by Hans Rieber in the 1960s and 1970s. Most fossils are concentrated at Point 902, occupying several distinct biostratigraphic zones recorded through the outcrop, bed-by-bed. Some of the most abundant fossils in the Besano Formation belong to the bivalve Daonella , with multiple species evolving in a sequence through the formation (according to the stratigraphic implications of Point 902). Italy%E2%80%93Switzerland border The border between

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1254-503: The Grenzbitumenzone are probably a consequence of sea level fluctuations. Raised sea levels would have submerged the carbonate platforms, which may have enhanced dolomite deposition in the basin. Alternatively, it would have connected the basin to other nutrient-rich areas, leading to phytoplankton blooms and thus more shale deposition. Laminations within dolomite layers correspond to fluctuating carbonate levels, possibly linked to runoff from carbonate platforms during storms. The sediments of

1311-408: The Grenzbitumenzone are undisturbed by benthic (seabed-living) organisms, while well-preserved fossils, organic matter, and heavy metal ions are prevalent. This evidence supports the traditional view that the seabed of the basin was completely anoxic – stagnant, oxygen-deprived, and lifeless. However, abundant fossils of nektonic (swimming) and planktonic (free-floating) life indicate that oxygen

1368-577: The Italian Domodossola valley, passing Gonda , Monte Leone , Bortelhorn , Helsenhorn , traversed by the Simplon Tunnel connecting Brig with Varzo , Grieshorn just south of Nufenen Pass , and forming the western border of Ticino runs across Marchhorn , Basodino , Pizzo Fiorera , Wandfluhhorn , Pizzo Quadro , Pizzo di Porcaresc , Pilone and descends below 1,000 metres (3,300 ft) running across Centovalli along

1425-773: The San Salvatore Dolomite further north and west, and the Esino Limestone further east. The Grenzbitumenzone basin may be up to 20 km wide, if the Perledo-Varenna Formation east of Lake Como also belongs to the basin. This system of carbonate platforms and basins developed along a western tongue of the Tethys Ocean , which transgressed eastwards during the Middle Triassic. Alternations between dolomite and shale in

1482-557: The San Salvatore Formation, exposed north of Monte San Giorgio, are partially isochronous with the Grenzbitumenzone (formed at the same time). At its upper extent, the Grenzbitumenzone grades into the San Giorgio Dolomite , a formation with fewer fossils and a lower concentration of organic matter. The San Giorgio Dolomite itself is succeeded by the fossil-rich Meride Limestone . As its name indicates,

1539-875: The Swiss canton of Valais from the Italian Aosta Valley and Piedmont region, the canton of Ticino from Piedmont and Lombardy , and the canton of Grisons from Lombardy and South Tyrol . Running east from Mont Dolent, the border touches Grand Golliat and the Great St Bernard Pass and then visits a series of three-thousander peaks including Mont Velan , Mont Brulé and Tête Blanche before rising to 4,171 metres (13,684 ft) at Dent d'Herens and to 4,476 metres (14,685 ft) at Matterhorn , followed by Furgghorn , Breithorn , Zwillinge , Monte Rosa at 4,554 metres (14,941 ft), and Grenzgipfel just east of Dufourspitze at 4,618 metres (15,151 ft). The border now encircles

1596-517: The ability to influence food resources on fish and other organisms in aquatic ecosystems . For example, the addition of a moderate amount of nutrients to a river over the course of several years resulted in increases in invertebrate richness, abundance, and biomass . These in turn resulted in increased food resources for native species of fish with insignificant alteration of the macroinvertebrate community structure and trophic pathways. The presence of macroinvertebrates such as Amphipoda also affect

1653-426: The basin from the anoxic lower part. There is little evidence for microbial activity on the seabed during the deposition of the Grenzbitumenzone. Later studies have argued that the seabed could have been dysoxic – with low oxygen levels, though still greater than in anoxic waters. Among the most common fossils belong to Daonella , a bivalve with strong debate over its habitat preferences. Early studies argued that it

1710-418: The benthic food chain ; most organisms in the benthic zone are scavengers or detritivores . Some microorganisms use chemosynthesis to produce biomass . Benthic organisms can be divided into two categories based on whether they make their home on the ocean floor or a few centimeters into the ocean floor. Those living on the surface of the ocean floor are known as epifauna . Those who live burrowed into

1767-969: The benthic zone. The microbes found in the benthic zone, specifically dinoflagellates and foraminifera , colonize quite rapidly on detritus matter while forming a symbiotic relationship with each other. In the deep sea, which covers 90–95% of the ocean floor, 90% of the total biomass is made up of prokaryotes. To release all the nutrients locked inside these microbes to the environment, viruses are important in making it available to other organisms. Modern seafloor mapping technologies have revealed linkages between seafloor geomorphology and benthic habitats, in which suites of benthic communities are associated with specific geomorphic settings. Examples include cold-water coral communities associated with seamounts and submarine canyons, kelp forests associated with inner shelf rocky reefs and rockfish associated with rocky escarpments on continental slopes. In oceanic environments, benthic habitats can also be zoned by depth. From

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1824-867: The course of the border date to 1873/4, 1936/7 and 1941. Since 1946, it has remained unchanged as the border between the Italian Republic and the Swiss Confederation, with the exception of minor corrections and exchanges of territory, such as the inclusion of the Lago di Lei barrage in Switzerland in the 1950s. In 2008 Switzerland became part of the Schengen Area , meaning that border controls were removed along this border as of 12 December 2008. However, while border guards from both countries are no longer allowed to stop travellers for

1881-439: The deposition of organic matter, and bacterial communities. The amount of material sinking to the ocean floor can average 307,000 aggregates per m per day. This amount will vary on the depth of the benthos, and the degree of benthic-pelagic coupling. The benthos in a shallow region will have more available food than the benthos in the deep sea. Because of their reliance on it, microbes may become spatially dependent on detritus in

1938-453: The depth of the water. As with oceans, the benthic zone is the floor of the lake, composed of accumulated sunken organic matter . The littoral zone is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The pelagic zone represents the broad mass of water, down as far as the depth to which no light penetrates. Benthos are the organisms that live in the benthic zone, and are different from those elsewhere in

1995-438: The dolomite, while vertebrates and radiolarian molds are preserved less often. Finely-laminated black shale with up to 40% organic matter makes up a smaller portion. Radiolarians and vertebrate fossils are common in the shale. However, invertebrates are practically absent, and crystals of dolomite and detrital quartz are rare. These major dolomite or shale layers show very little evidence of bioturbation or disturbance. Pyrite

2052-462: The dominance of certain types of algae in Benthic ecosystems as well. In addition, because benthic zones are influenced by the flow of dead organic material , there have been studies conducted on the relationship between stream and river water flows and the resulting effects on the benthic zone. Low flow events show a restriction in nutrient transport from benthic substrates to food webs, and caused

2109-410: The eastern border of Ticino running west of Lake Como , of passing Lake Lugano again east of Lugano and touching Monte Boglia , Cima di Fojorina , Gazzirola , Cima di Cugn , Pizzo Campanile , again reaching 3,000 metres (9,800 ft) at Pizzo Quadro between Val Mesolcina and Chiavenna , and further north to Pizzo Tambo , Splügen Pass and Piz Timun . The Swiss-Italian border here has

2166-652: The ecological status of lakes in the UK. Beginning research is being made on benthic assemblages to see if they can be used as indicators of healthy aquatic ecosystems. Benthic assemblages in urbanized coastal regions are not functionally equivalent to benthic assemblages in untouched regions. Ecologists are attempting to understand the relationship between heterogeneity and maintaining biodiversity in aquatic ecosystems. Benthic algae has been used as an inherently good subject for studying short term changes and community responses to heterogeneous conditions in streams. Understanding

2223-542: The formation. They are mostly composed of illite and montmorillonite , with occasional crystals of sanidine . Unlike most Triassic tuffs from the Southern Alps, plagioclase crystals are completely absent. The formation is representative of a small intraplatform basin , a deep and stable marine environment which would have been positioned among shallow-water reefs and carbonate platforms . The carbonate platforms themselves are preserved in thick sequences, such as

2280-479: The future. Currently, connections exist through bus routes over these passes. The highest border crossing by cable car is at Testa Grigia (3,458 m (11,345 ft)). It is also the highest Alpine crossing, culminating near the summit of the Klein Matterhorn at 3,821 m (12,536 ft) above sea level. In 2016, due to increased illegal immigration from Italy into Switzerland related to

2337-431: The head, a heavy part of the skeleton which is most likely to sink first, detaching from the rest of a floating body. Even so, headless and relatively incomplete specimens are rare, so bodies are unlikely to fall apart while floating for an extended period. The vertebrae and ribs tend to be disarticulated, though only over a short distance. Peripheral elements such as the toes are also prone to disarticulation. Disarticulation

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2394-575: The low sedimentation rate of the Grenzbitumenzone relative to the Meride Limestone, providing more time for the influence of bottom currents prior to burial. The Cassina beds also have more direct evidence for microbial mats, which could have played a role in stabilizing decaying carcasses. Conversely, ichthyosaur fossils of the Grenzbitumenzone tend to have higher completeness than those found in Early Jurassic formations elsewhere in Europe. There

2451-603: The modern states of Switzerland and Italy extends for 744 kilometres (462 mi), from the French-Swiss-Italian tripoint at Mont Dolent in the west to the Austrian-Swiss-Italian tripoint near Piz Lad in the east. Much of the border runs across the High Alps , rising above 4,600 metres (15,100 ft) as it passes east of Dufourspitze , but it also descends to the lowest point in Switzerland as it passes Lago Maggiore at below 200 metres (660 ft). It

2508-403: The ocean begins at the shore line ( intertidal or littoral zone ) and extends downward along the surface of the continental shelf out to sea. Thus, the region incorporates a great variety of physical conditions differing in: depth, light penetration and pressure. Depending on the water-body, the benthic zone may include areas that are only a few inches below the surface. The continental shelf

2565-456: The ocean floor are known as infauna . Extremophiles, including piezophiles , which thrive in high pressures, may also live there. An example of benthos organism is Chorismus antarcticus . Sources of food for benthic communities can derive from the water column above these habitats in the form of aggregations of detritus , inorganic matter, and living organisms. These aggregations are commonly referred to as marine snow , and are important for

2622-890: The past to extend the Rhaetian Railway (RhB) network from St. Moritz to Chiavenna through a tunnel under the Maloja Pass ( Malojatunnel ). Similarly, there have been plans to connect the Vinschgau Railway ( Mals/Malles – Meran/Merano ) in South Tyrol with the RhB network at either Zernez through a tunnel under the Ofen Pass ( Ofenbergbahn ) or Scuol-Tarasp via the Reschenscheideckbahn . Some of these plans are currently reconsidered for

2679-645: The peculiarity of including the reservoir of Lago di Lei in Italy but in an artificial salient including the reservoir's dam in Switzerland. Turning south again it traverses Val Bregaglia at Castasegna and turns east towards Cima di Castello , now forming the northern border of the Valtellina , a territory that was lost by the Three Leagues in 1797 with the formation of the Cisalpine Republic . Val Poschiavo remains part of Grisons, and

2736-471: The potential mechanisms involving benthic periphyton and the effects on heterogeneity within a stream may provide a better understanding of the structure and function of stream ecosystems. Periphyton populations suffer from high natural spatial variability while difficult accessibility simultaneously limits the practicable number of samples that can be taken. Targeting periphyton locations which are known to provide reliable samples – especially hard surfaces –

2793-482: The rest of Italy, but the intervening mountainous terrain requires a journey by road of over 14 km (9 mi) to reach the nearest Italian town, Lanzo d'Intelvi , and over 28 km (17 mi) to reach the city of Como . The entire territory of the Italian village was de facto included in the Swiss Customs Area as per a unilateral decision by the Swiss authorities. Being an exclave of Italy, it

2850-442: The sediments of the formation are bituminous , rich in organic matter to the point that they burn readily. Grey laminated (finely-layered) dolomite with about 20% organic matter comprises the majority of the formation. The width of laminae in these dolomite layers vary widely from sub-millimeter to sub-centimeter scales, as a function of mineral or grain size variation. Invertebrate fossils and isolated quartz grains are common in

2907-664: The shallowest to the deepest are: the epipelagic (less than 200 meters), the mesopelagic (200–1,000 meters), the bathyal (1,000–4,000 meters), the abyssal (4,000–6,000 meters) and the deepest, the hadal (below 6,000 meters). The lower zones are in deep, pressurized areas of the ocean. Human impacts have occurred at all ocean depths, but are most significant on shallow continental shelf and slope habitats. Many benthic organisms have retained their historic evolutionary characteristics. Some organisms are significantly larger than their relatives living in shallower zones, largely because of higher oxygen concentration in deep water. It

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2964-557: The sole purpose of passport checks, they can still carry out customs checks, as Switzerland is not in the EU Customs Union . In May 2023, a joint Italian-Swiss commission agreed to redraw a border that traverses an Alpine peak as melting glaciers shift the historically defined frontier. Switzerland officially approved the treaty in September 2024, but Italy still needs to sign. The border as shown by Swisstopo separates

3021-442: The substrate (bottom). In their habitats they can be considered as dominant creatures, but they are often a source of prey for Carcharhinidae such as the lemon shark . Because light does not penetrate very deep into ocean-water, the energy source for the benthic ecosystem is often marine snow . Marine snow is organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains

3078-447: The substrate and many are permanently attached to the bottom. The benthic boundary layer , which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral , and bay mud . The benthic region of

3135-470: Was pseudoplanktonic (attached to floating objects) or washed in from shallower areas, congruent with an anoxic Grenzbitumenzone seabed. However, Daonella is now believed to have lived in place at the bottom of the basin, specializing in a dysoxic environment inhospitable to most other benthic animals. Disarticulation and reorientation of Grenzbitumenzone fossils have favored the presence of weak and oxygenated bottom currents. Early evidence for bottom currents

3192-506: Was controversial and perhaps based on a misdrawn illustration, but further specimen sampling supports the same general conclusion. Grenzbitumenzone fossils are usually well-preserved, but most are compressed between sediment layers. Compaction is much more pronounced in the thin shale layers than the thicker dolomite layers. Soft tissue preservation is rare but not unheard of: it includes calcified shark cartilage, phosphatized coprolites and gut contents, and organic remnants of reptile scales. In

3249-433: Was more concentrated in seawater closer to the surface. There has been debate over the origin or intensity of this strong stratification in oxygen content. The basin, though relatively deep, was likely too shallow for stratification via deep saline currents or a strong temperature gradient. The traditional view places blame on a concentration of planktonic bacteria at mid-level in the water column, dividing an oxic upper part of

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