The Iapetus Ocean was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale. The Iapetus Ocean was situated in the southern hemisphere, between the paleocontinents of Laurentia and Avalonia; the ocean disappeared with the Acadian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between Western Gondwana and Laurentia; because the Iapetus Ocean was positioned between continental masses that would at a much time form the opposite shores of the Atlantic Ocean, it can be seen as a sort of precursor of the Atlantic. The Iapetus Ocean was therefore named for the titan Iapetus, who in Greek mythology was the father of Atlas, after whom the Atlantic Ocean was named. At the start of the 20th century, American paleontologist Charles Walcott noticed differences in early Paleozoic benthic trilobites of Laurentia, as found in Scotland and western Newfoundland and those of Baltica, as found in the southern parts of the British Isles and eastern Newfoundland.
Geologists of the early 20th century presumed that a large trough, a so-called geosyncline, had existed between Scotland and England in the early Paleozoic, keeping both sides separated. With the development of plate tectonics in the 1960s, geologists such as Arthur Holmes and John Tuzo Wilson concluded that the Atlantic Ocean must have had a precursor before the time of Pangaea. Wilson noticed that the Atlantic had opened at the same place where its precursor ocean had closed; this led him to his Wilson cycle hypothesis. In many spots in Scandinavia basaltic dikes are found with 650 million years; these are interpreted as evidence that by that time, rifting had started that would form the Iapetus Ocean. In Newfoundland and Labrador, the Long Range dikes are thought to have formed during the formation of the Iapetus Ocean, it has been proposed that both the Fen Complex in Norway and the Alnö Complex in Sweden formed as consequence to mild extensional tectonics in the ancient continent of Baltica that followed the opening of the Iapetus Ocean.
The southern Iapetus Ocean opened between Laurentia and southwestern Gondwana about 550 Ma in the Ediacaran–Cambrian transition. At the time it did; the opening of the Iapetus Ocean postdates the opening of the Puncoviscana Ocean with the Iapetus Ocean being separated from the Puncoviscana Ocean by the ribbon-shaped Arequipa-Antofalla terrane. However, the formation of both oceans seems unrelated. Southwest of the Iapetus, a volcanic island arc evolved from the early Cambrian onward; this volcanic arc was formed above a subduction zone where the oceanic lithosphere of the Iapetus Ocean subducted southward under other oceanic lithosphere. From Cambrian times the western Iapetus Ocean began to grow progressively narrower due to this subduction; the same happened further north and east, where Avalonia and Baltica began to move towards Laurentia from the Ordovician onward. Trilobite faunas of the continental shelves of Baltica and Laurentia are still different in the Ordovician, but Silurian faunas show progressive mixing of species from both sides, because the continents moved closer together.
In the west, the Iapetus Ocean closed with the Taconic orogeny, when the volcanic island arc collided with Laurentia. Some authors consider the oceanic basin south of the island arc a part of the Iapetus, this branch closed during the Acadian orogeny, when Avalonia collided with Laurentia, it has been suggested that the southern Iapetus Ocean closed during a continental collision between Laurentia and Western Gondwana. If factual the Taconic orogen would be the northward continuation of the Famatinian orogen exposed in Argentina. Meanwhile, the eastern parts had closed too: the Tornquist Sea between Avalonia and Baltica during the late Ordovician, the main branch between Baltica-Avalonia and Laurentia during the Grampian and Scandian phases of the Caledonian orogeny. At the end of the Silurian period the Iapetus Ocean had disappeared and the combined mass of the three continents formed the "new" continent of Laurasia, which would itself be the northern component of the singular supercontinent of Pangaea.
Avalonia – A microcontinent in the Paleozoic era Baltica – Late-Proterozoic to early-Palaeozoic continent Geologic timescale Khanty Ocean – A small Precambrian ocean between Baltica and the Siberian continent List of ancient oceans – A list of former oceans that disappeared due to tectonic movements and other geographical and climatic changes London-Brabant Massif Plate tectonics – The scientific theory that describes the large-scale motions of Earth's lithosphere Southern uplands of Scotland Cocks, L. R. N.. A.. "Biogeography of Ordovician and Silurian faunas". In McKerrow, W. S.. Geological Society of London Memoirs. 12. Pp. 97–104. Doi:10.1144/GSL. MEM.1990.012.01.08. Dalziel, I. W.. "Neoproterozoic-Paleozoic geography and tectonics: Review, environmental speculation". Geological Society of America Bulletin. 109: 16–42. Doi:10.1130/0016-7606109<0016:ONPGAT>2.3. CO. Harland, W. B. & Gayer, R. A.. Meert, J. G. & Torsvi
The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, placed them in a system of their own; the Ordovician received international approval in 1960, when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, although the end of the period was marked by the Ordovician–Silurian extinction events.
Invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event increased the diversity of life. Fish, the world's first true vertebrates, continued to evolve, those with jaws may have first appeared late in the period. Life had yet to diversify on land. About 100 times as many meteorites struck the Earth per year during the Ordovician compared with today; the Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event, about 485.4 Mya. It lasted for about 42 million years and ended with the Ordovician–Silurian extinction events, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary from those found in other sources; this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is significant, it correlates well with the occurrence of widespread graptolite and trilobite species.
The base of the Tremadocian allows scientists to relate these species not only to each other, but to species that occur with them in other areas. This makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of regional terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected a formal international system of subdivisions. There exist Baltoscandic, Siberian, North American, Chinese Mediterranean and North-Gondwanan regional stratigraphic schemes; the Ordovician Period in Britain was traditionally broken into Early and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, or Upper part of the column; the faunal stages from youngest to oldest are: Late Ordovician Hirnantian/Gamach Rawtheyan/Richmond Cautleyan/Richmond Pusgillian/Maysville/Richmond Middle Ordovician Trenton Onnian/Maysville/Eden Actonian/Eden Marshbrookian/Sherman Longvillian/Sherman Soudleyan/Kirkfield Harnagian/Rockland Costonian/Black River Chazy Llandeilo Whiterock Llanvirn Early Ordovician Cassinian Arenig/Jefferson/Castleman Tremadoc/Deming/Gaconadian The Tremadoc corresponds to the Tremadocian.
The Floian corresponds to the lower Arenig. The Llanvirn occupies the rest of the Darriwilian, terminates with it at the base of the Late Ordovician; the Sandbian represents the first half of the Caradoc. During the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician, the continents of Laurentia and Baltica were still independent continents, but Baltica began to move towards Laurentia in the period, causing the Iapetus Ocean between them to shrink; the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia. The Taconic orogeny, a major mountain-building episode, was well under way in Cambrian times. In the early and middle Ordovician, temperatures were mild, but at the beginning of the Late Ordovician, from 460 to 450 Ma, volcanoes along the margin of the Iapetus Ocean spewed massive amounts of carbon dioxide, a greenhouse gas, into the atmosphere, turning the planet into a hothouse.
Sea levels were high, but as Gondwana moved south, ice accumulated into glaciers and sea levels dropped. At first, low-lying sea beds increased diversity, but glaciation led to mass extinctions as the seas drained and continental shelves became dry land. During the Ordovician, in fact during the Tremadocian, marine transgressions worldwide were the greatest for which evidence is preserved; these volcanic island arcs collided with proto North America to form the Appalachian mountains. By the end of the Late Ordovician the volcanic emissions had stopped. Gondwana had by that time neared the South Pole and was glaciated
Siberia known as Angaraland and Angarida, is an ancient craton located in the heart of Siberia. Today forming the Central Siberian Plateau, it formed an independent continent before the Permian period. Angaraland was named in the 1880s by Austrian geologist Eduard Suess who erroneously believed that in the Paleozoic there were two large continents in the Northern Hemisphere: "Atlantis", North America connected to Europe by a peninsula. About 2.5 billion years ago, Siberia was part of a continent of Arctica, along with the Canadian Shield. Around 1.1 billion years ago, Siberia became part of the major supercontinent of Rodinia, a state of affairs which lasted until the Cryogenian about 750 million years ago when it broke up, Siberia became part of the minor supercontinent of Protolaurasia. During the Ediacaran Period around 600 million years ago, Protolaurasia became part of the major southern supercontinent of Pannotia but around 550 million years ago, both Pannotia and Protolaurasia split up to become the continents of Laurentia and Siberia.
Siberia was an independent continent through the lower Paleozoic until, during the Carboniferous Period, it collided with the minor continent of Kazakhstania. A subsequent collision with Baltica during the Permian completed the formation of the supercontinent Pangaea; the Siberian Traps formed. Pangaea split up during the Jurassic. Laurasia split up during the Cretaceous with Siberia remaining part of present-day northeastern Eurasia. Today, Siberia forms part of the minor supercontinent of Afro-Eurasia. In around 250 million years from now Siberia may be in the subtropical region and part of a new supercontinent of Pangaea Ultima. Blakey, R. "Global Earth History: Sedimentation and Paleogeography of Asia". Northern Arizona University. Retrieved 25 October 2015
Pannotia known as Vendian supercontinent, Greater Gondwana, the Pan-African supercontinent, was a short-lived Neoproterozoic supercontinent that formed at the end of the Precambrian during the Pan-African orogeny and broke apart 560 Ma with the opening of the Iapetus Ocean. Pannotia formed when Laurentia was located adjacent to the two major South American cratons, Amazonia and Río de la Plata; the opening of the Iapetus Ocean separated Laurentia from Baltica, Río de la Plata. Piper 1976 was the first to propose a Proterozoic supercontinent preceding Pangaea, today known as Rodinia. At that time he referred to it as "the Proterozoic super-continent", but much he named this "symmetrical crescent-shaped analogue of Pangaea"'Palaeopangaea' and still insists there is neither a need nor any evidences for Rodinia or its daughter supercontinent Pannotia or a series of other proposed supercontinents since Archaean times; the existence of a Late Proterozoic supercontinent, much different from Pangaea, was first proposed by McWilliams 1981 based on paleomagnetic data and the break-up of this supercontinent around 625–550 Ma was documented by Bond, Nickeson & Kominz 1984.
The reconstruction of Bond et al. is identical to that of Dalziel 1997 and others. Another term for the supercontinent, thought to have existed at the end of Neoproterozoic time is "Greater Gondwanaland", suggested by Stern 1994; this term recognizes that the supercontinent of Gondwana, which formed at the end of the Neoproterozoic, was once part of the much larger end-Neoproterozoic supercontinent. Pannotia was named by Powell 1995, based on the term "Pannotios" proposed by Stump 1987 for "the cycle of tectonic activity common to the Gondwana continents that resulted in the formation of the supercontinent." Young 1995 proposed renaming the older Proterozoic supercontinent "Kanatia", the St. Lawrence Iroquoian word from which the name'Canada' is derived, while keeping the name Rodinia for the latter Neoproterozoic supercontinent. Powell, objected to this renaming and instead proposed Stump's term for the latter supercontinent. Reconstructions of Rodinia varies but most include five elements: Laurentia or the Canadian Shield is located at the centre.
Less certain position of continental blocks includes: the West African Craton was an extension of the Amazonian Craton. The formation of Pannotia began during the Pan-African orogeny when the Congo continent got caught between the northern and southern halves of the previous supercontinent Rodinia some 750 Ma; the peak in this mountain building event was around 640–610 Ma, but these continental collisions may have continued into the Early Cambrian some 530 Ma. The formation of Pannotia was the result of Rodinia turning itself inside out; when Pannotia had formed, Africa was located at the centre surrounded by the rest of Gondwana: South America, Madagascar, India and Australia. Laurentia, which'escaped' out of Rodinia and Siberia kept the relative positions they had in Rodinia; the Cathaysian and Cimmerian terranes were located along the northern margins of east Gondwana. The Avalonian-Cadomian terranes were located along the active northern margins of western Gondwana; this orogeny extended north into the Uralian margin of Baltica.
Pannotia formed by subduction of exterior oceans over a geoid low, whereas Pangaea formed by subduction of interior oceans over a geoid high caused by superplumes and slab avalanche events. The oceanic crust subducted by Pannotia formed within the Mirovoi superocean that surrounded Rodinia before its 830–750 Ma break-up and were accreted during the Late Proterozoic orogenies that resulted from the assembly of Pannotia. One of the major of these orogenies was the collision between East and West Gondwana or the East African Orogeny; the Trans-Saharan Belt in West Africa is the result of the collision between the East Saharan Shield and the West African Craton when 1200–710 Ma-old volcanic and arc-related rocks were accreted to the margin of this craton. 600–500 Ma two Brazilian interior orogenies got deformed and metamorphosed between a series of colliding cratons: Amazonia, West Africa-São Luís, São Francisco-Congo-Kasai. The material, accreted included 950–850 Ma mafic meta-igneous complexes and younger arc-related rocks.
The break-up of Pannotia was accompanied by sea level rise, dramatic changes in climate and ocean water chemistry, rapid metazoan diversification. Bond, Nickeson & Kominz 1984 found Neoproterozoic passive margin sequences worldwide – the first indication of a Late Neoproterozoic supercontinent but the traces of its demise; the Iapetus Ocean started to open while Pannotia was being assembled, 200 Ma after the break-up of Rodinia. This opening of the Iapetus and other Cambrian seas coincided with the first steps in the evolution of soft-bodied metazoans, made a myriad of habitats available for them.
Back-arc basins are geologic basins, submarine features associated with island arcs and subduction zones. They are found at some convergent plate boundaries, presently concentrated in the western Pacific Ocean. Most of them result from tensional forces caused by oceanic trench rollback and the collapse of the edge of the continent; the arc crust is under extension or rifting as a result of the sinking of the subducting slab. Back-arc basins were a surprising result for plate tectonics theorists, who expected convergent boundaries to be zones of compression, rather than major extension. However, they are now recognized as consistent with this model in explaining how the interior of Earth loses heat. Back-arc basins are very long and narrow; the restricted width of back-arc basins is because magmatic activity depends on water and induced mantle convection and these are both concentrated near the subduction zone. Spreading rates vary from slow spreading, a few centimeters per year, to fast, 15 cm/year.
These ridges erupt basalts. The high water contents of back-arc basin basalt magmas is derived from water carried down the subduction zone and released into the overlying mantle wedge. Additional source of water could be the eclogitization of amphiboles and micas in the subducting slab. Similar to mid-ocean ridges, back-arc basins have hydrothermal vents and associated chemosynthetic communities. Evidence of this spreading came from cores of the basin floor; the thickness of sediment that collected in basin decreased toward the center of the basin. The idea that thickness and age of sediment on the sea floor is related to the age of the oceanic crust was proposed by Harry Hess. Magnetic anomalies of the crust formed in back-arc basins deviated in form from the crust formed at mid-ocean ridges. In many areas the anomalies do not appear parallel; the profiles of the magnetic anomalies in the basin do not show symmetry or a central anomaly as a traditional ocean basin does. This has prompted some to characterize the spreading in back-arc basins to be more diffused and less uniform than at mid-ocean ridges.
The idea that back-arc basin spreading is inherently different that mid-ocean ridge spreading has been debated though the years. Other arguments put forward is that the process of seafloor spreading is the same but the movement of seafloor spreading centers in the basin causes the asymmetry in the magnetic anomalies; this can be seen in the Lau back-arc basin. Though the magnetic anomalies are more complex to decipher the rocks sampled from back-arc basin spreading centers do not differ much from those at mid-ocean ridges; the volcanic rocks of the nearby island arc do differ from those in the basin. Back-arc basins are different from normal mid-ocean ridges because they are characterized by asymmetric seafloor spreading, but this is quite variable within single basins. For example, in the central Mariana Trough current spreading rates are 2-3 times greater on the western flank whereas at the southern end of the Mariana Trough the position of the spreading center adjacent to the volcanic front suggests that overall crustal accretion has been nearly 100% asymmetric there.
This situation is mirrored to the north where a large spreading asymmetry is developed. Other back-arc basins such as the Lau Basin have undergone large rift jumps and propagation events that have transferred spreading centers from arc-distal to more arc-proximal positions although recent spreading rates appear to be symmetric with small rift jumps; the cause of asymmetric spreading in back-arc basins remains poorly understood. General ideas invoke asymmetries relative to the spreading axis in arc melt generation processes and heat flow, hydration gradients with distance from the slab, mantle wedge effects, evolution from rifting to spreading; the extension of the crust behind volcanic arcs is believed to be caused by processes in association with subduction. As the subducting plate descends into the asthenosphere it is heated up causing the volcanism at the island arcs. Another result of this heating is a convection cell; the rising magma and heat in the convection cell cause a rift to form.
This rift drives the island arc toward the subduction zone and the rest of the plate away from the subduction zone. This process is known as trench rollback; this is the backward motion of the subduction zone relative to the motion of the plate, being subducted. As the subduction zone and its associated trench pull backward, the overriding plate is stretched, thinning the crust, manifest in the back-arc basin. Therefore, back-arc basins form. In some cases, extension is triggered by the entrance of a buoyant feature in the subduction zone, which locally slows down subduction and induce the subducting plate to rotate adjacent to it; this rotation is associated with overriding plate extension. For back-arc extension to form, a subduction zone is required, but not all subduction zones have a back-arc extension feature. Back-arc basins are found in areas where the subducting plate of oceanic crust is old; the age need to establish back-arc spreading is oceanic lithosphere, 55 million years old or older.
This includes areas like the western pacific where
The Tethys Ocean called the Tethys Sea or the Neotethys, was an ocean during much of the Mesozoic Era located between the ancient continents of Gondwana and Laurasia, before the opening of the Indian and Atlantic oceans during the Cretaceous Period. The name stems from the mythological Greek sea goddess Tethys and consort of Oceanus, mother of the great rivers and fountains of the world and of the Oceanid sea nymphs; the eastern part of the Tethys Ocean is sometimes referred to as Eastern Tethys. The western part of the Tethys Ocean is called Tethys Sea, Western Tethys Ocean, or Paratethys or Alpine Tethys Ocean; the Black and Aral seas are thought to be its crustal remains, though the Black Sea may, in fact, be a remnant of the older Paleo-Tethys Ocean. The Western Tethys was not a single open ocean, it covered many small plates, Cretaceous island arcs, microcontinents. Many small oceanic basins were separated from each other by continental terranes on the Alboran and Apulian plates; the high sea level in the Mesozoic flooded most of these continental domains.
As theories have improved, scientists have extended the "Tethys" name to refer to three similar oceans that preceded it, separating the continental terranes: in Asia, the Paleo-Tethys, Meso-Tethys, Ceno-Tethy are recognized. Neither Tethys Ocean should be confused with the Rheic Ocean, which existed to the west of them in the Silurian Period. To the north of the Tethys, the then-land mass was called Angaraland and to the south of it, it was called Gondwanaland. From the Ediacaran into the Devonian, the Proto-Tethys Ocean existed and was situated between Baltica and Laurentia to the north and Gondwana to the south. From the Silurian through the Jurassic periods, the Paleo-Tethys Ocean existed between the Hunic terranes and Gondwana. Over a period of 400 million years, continental terranes intermittently separated from Gondwana in the Southern Hemisphere to migrate northward to form Asia in the Northern Hemisphere. About 250 Mya, during the Triassic, a new ocean began forming in the southern end of the Paleo-Tethys Ocean.
A rift formed along the northern continental shelf of Southern Pangaea. Over the next 60 million years, that piece of shelf, known as Cimmeria, traveled north, pushing the floor of the Paleo-Tethys Ocean under the eastern end of northern Pangaea; the Tethys Ocean formed between Cimmeria and Gondwana, directly over where the Paleo-Tethys used to be. During the Jurassic period about 150 Mya, Cimmeria collided with Laurasia and stalled, so the ocean floor behind it buckled under, forming the Tethyan Trench. Water levels rose, the western Tethys shallowly covered significant portions of Europe, forming the first Tethys Sea. Around the same time and Gondwana began drifting apart, opening an extension of the Tethys Sea between them which today is the part of the Atlantic Ocean between the Mediterranean and the Caribbean; as North and South America were still attached to the rest of Laurasia and Gondwana the Tethys Ocean in its widest extension was part of a continuous oceanic belt running around the Earth between about latitude 30°N and the Equator.
Thus, ocean currents at the time around the Early Cretaceous ran differently from the way they do today. Between the Jurassic and the Late Cretaceous, which started about 100 Mya, Gondwana began breaking up, pushing Africa and India north across the Tethys and opening up the Indian Ocean; as these land masses crowded in on the Tethys Ocean from all sides, to as as the Late Miocene, 15 Mya, the ocean continued to shrink, becoming the Tethys Seaway or second Tethys Sea. Throughout the Cenozoic, global sea levels fell hundreds of meters, the connections between the Atlantic and the Tethys closed off in what is now the Middle East. During the Oligocene, large parts of central and eastern Europe were covered by a northern branch of the Tethys Ocean, called the Paratethys; the Paratethys was separated from the Tethys with the formation of the Alps, Dinarides and Elburz mountains during the Alpine orogeny. During the late Miocene, the Paratethys disappeared, became an isolated inland sea. In 1885, the Austrian palaeontologist Melchior Neumayr deduced the existence of the Tethys Ocean from Mesozoic marine sediments and their distribution, calling his concept Zentrales Mittelmeer and described it as a Jurassic seaway, which extended from the Caribbean to the Himalayas.
In 1893, the Austrian geologist Eduard Suess proposed the theory that an ancient and extinct inland sea had once existed between Laurasia and the continents which formed Gondwana II. He named it the Tethys Sea after the Greek sea goddess Tethys, he provided evidence for his theory using fossil records from the Africa. He proposed the concept of Tethys in his four-volume work Das Antlitz der Erde. In the following decades during the 20th century, "mobilist" geologists such as Uhlig and Daque regarded Tethys as a large trough between two supercontinents which lasted from the late Palaeozoic until continental fragments derived from Gondwana obliterated it. After World War II, Tethys was described as a triangular ocean with a wide eastern end. From 1920s to the 1960s, "fixist" geologists, regarded Tethys as a composite trough, which evolved through a series of orogenic cycles, they used the terms'Paleotethys','Mesotethys', and'Neotethys' for the Caledonian and Alpine orogenies, respe
Chamrousse is a ski resort in southeastern France, in the Belledonne mountain range near Grenoble in the Isère department. It is located in a commune of the same name and is situated on the Recoin at 1,650 m and the Roche Béranger at 1,750 m; the ski-lifts reach the Cross of Chamrousse at 2,253 m. Chamrousse hosted the six alpine skiing events of the 1968 Winter Olympics, where Jean-Claude Killy of France won three gold medals in the men's events. All women's events took place at Recoin de Chamrousse, located 2 km away. There are more than 90 km of downhill runs at 24 ski lifts. There are 37 km of trails for cross-country skiing. Cross-country skiing can be practised from the opening of the resort to mid-April; the road to the ski station starts at Uriage-les-Bains from where the climb is 19 km long, gaining 1,235 m in altitude, at an average gradient of 6.5%. There are several sections in excess off 11% in the early stages of the climb. For the Tour de France, the summit is at an altitude of 1,730 m.
The ski station can be reached by a more northerly route, from Uriage-les-Bains via Saint-Martin-d'Uriage. This climb is 18.2 km gaining 1,315 m in altitude, at an average gradient of 7.2%. The climb of Chamrousse was used in the mountain time-trial in the 2001 Tour de France. Lance Armstrong won the stage on 18 July 2001, when he took just over an hour to complete the hors categorie climb from Grenoble to the ski resort. In 2012, Armstrong was disqualified from winning this stage, following the Lance Armstrong doping case; the ski station was re-visited by the race on 18 July 2014. The winner of the 197 km stage 13 from Saint-Étienne was the Italian Vincenzo Nibali who increased his lead over his nearest rivals, with Richie Porte, who began the day second overall, losing nine minutes on the climb. Media related to Chamrousse at Wikimedia Commons Official website guide web touristique INSEE statistics