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48-544: Seymour Island or Marambio Island , is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula . Graham Land is the closest part of Antarctica to South America. It lies within the section of the island chain that resides off the west side of the peninsula's northernmost tip. Within that section, it is separated from Snow Hill Island by Picnic Passage, and sits just east of

96-504: A member of the enigmatic extinct order Gondwanatheria , possibly Sudamerica ameghinoi . In respect of the site being the 'most representative high latitude K-Pg boundary location and one of the most significant and best exposed globally' the 'Cretaceous-Paleogene Transition at Seymour (Marambio) Island' was included by the International Union of Geological Sciences (IUGS) in its assemblage of 100 'geological heritage sites' around

144-631: A northward course towards Asia. In the Southern Hemisphere, Australia and Antarctica seem to have remained connected and began to drift away from Africa and South America. Europe was an island chain. Populating some of these islands were endemic dwarf dinosaur species. In the Late Cretaceous, the hadrosaurs , ankylosaurs , and ceratopsians experienced success in Asiamerica (Western North America and eastern Asia). Tyrannosaurs dominated

192-519: A northwest–southeast direction, cutting through the mid-part of Seymour Island. Discovered by the SwedAE under Otto Nordenskjöld, 1901-04, and named Querthal (cross valley) because of the transverse alignment of the valley. 64°16′S 56°39′W  /  64.267°S 56.650°W  / -64.267; -56.650 . A bight on the southeast coast of Seymour Island, northward of Penguin Point. The feature

240-581: A single and severe mass extinction event occurred at this time in Antarctica just as at lower latitudes. Seymour Island has also been the site of much study of the Eocene Epoch of climatic cooling, a process that culminated in the initiation of Antarctic glaciation . Studies of the fine fraction carbonate from sites in the Southern Ocean suggest that, rather than a monotonic decrease in temperature over

288-536: A very different dinosaurian fauna, with most predators being abelisaurids and carcharodontosaurids ; and titanosaurs being among the dominant herbivores. Spinosaurids were also present during this time. Birds became increasingly common, diversifying in a variety of enantiornithe and ornithurine forms. Early Neornithes such as Vegavis co-existed with forms as bizarre as Yungavolucris and Avisaurus . Though mostly small, marine Hesperornithes became relatively large and flightless, adapted to life in

336-473: Is entirely snow-free and of remarkable appearance. The northern portion of the island is a high, level, extensive plateau which reaches an elevation of 591 feet. Below this smooth plateau are terraces containing valleys and small irregular knolls of hard rock. A transverse valley, the bottom of which is not much above sea level, cuts through the island from east to west. This valley opens into Papua Beach (Penguin Bay) on

384-474: Is it particularly evident that a true systematic decline was ever in place, especially with the discovery of smaller pterosaur species. Several old mammal groups began to disappear, with the last eutriconodonts occurring in the Campanian of North America . In the northern hemisphere, cimolodont , multituberculates , metatherians and eutherians were the dominant mammals, with the former two groups being

432-407: Is separated by a strait about 1 mile wide. Strong currents and tide rips exist in this channel which shoals to less than 1.8mi (1 nm) in the center of the channel at low tide. The bottom deepens steeply on the northwestern side of the channel. The Island is 8 miles long and about 4 miles wide opposite Bodman Point (Cape Bodman) on the northwestern coast; the ends on the island are about 2 miles wide. It

480-649: Is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale . Rock strata from this epoch form the Upper Cretaceous Series . The Cretaceous is named after creta , the Latin word for the white limestone known as chalk . The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. During the Late Cretaceous,

528-554: The Jason , on Seymour Island, he returned with more than maps of the territory, he found fossils of long- extinct species. Larsen's trip aboard the Jason was significantly more successful than his Swedish Antarctic Expedition journey between 1901 and 1904. During that trip, his ship, the Antarctic , was crushed and sunk by icebergs , and he and his crew were forced to weather fourteen months on

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576-569: The Chicxulub impactor in the Gulf of Mexico. Directly above the boundary a layer of disarticulated fish fossils occurs, victims of a disturbed ecosystem immediately following the impact event. Multiple reports have described evidence for climatic changes in Antarctica prior to the mass extinction, but the extent to which these affected marine biodiversity is debated. Based on extensive marine fossil collections from Seymour Island, recent work has confirmed that

624-415: The bivalvia class and various types of flora and fauna , including a frog. A fossil marsupial of the extinct family Polydolopidae was found on Seymour Island in 1982. This was the first evidence of land mammals having lived in Antarctica. Further fossils have subsequently been found, including members of the marsupial orders Didelphimorphia (opossum) and Microbiotheria , as well as ungulates and

672-642: The Argentinian Corvette Uruguay on a mission to rescue the members of the Swedish expedition led by Otto Nordenskiöld . The inscription on the plaque, placed where the two parties met, reads: “10.XI.1903 Uruguay (Argentine Navy) in its journey to give assistance to the Swedish Antarctic expedition”. The cairn was erected in January 1990 by Argentina at the site of the plaque in commemoration of

720-813: The Cretaceous Period derived from the German name Kreidezeit , and T is the abbreviation for the Tertiary Period (a historical term for the period of time now covered by the Paleogene and Neogene periods). The event marks the end of the Mesozoic Era and the beginning of the Cenozoic Era. "Tertiary" being no longer recognized as a formal time or rock unit by the International Commission on Stratigraphy ,

768-584: The Eocene Epoch, the middle of the epoch was punctuated by a brief duration of warming (Bohaty and Zachos, 2003). Seymour Island has been a site of study of many fossils from this particular part of the Eocene Epoch, during which there was a more flourishing ecosystem with diverse biota as a result of the warmer climate. A diverse array of fossilized species has been studied on the island, including extinct penguin species (such as Palaeeudyptes klekowskii and Archaeospheniscus wimani ), various species in

816-745: The James Ross Island group. First surveyed by the Swedish Antarctic Expedition (SwedAE) under Otto Nordenskjöld , 1901-04, who named it Cape Bodman after Doctor Gosta Bodman, hydrographer and meteorologist with the expedition. Resurveyed by the Falkland Islands Dependencies Survey (FIDS) in 1952. Point is considered a more suitable descriptive term for this feature than cape. 64°15′S 56°44′W  /  64.250°S 56.733°W  / -64.250; -56.733 . A bay between Bodman Point and Cape Wiman on

864-847: The K-T event is now called the Cretaceous—Paleogene (or K-Pg) extinction event by many researchers. Non- avian dinosaur fossils are found only below the Cretaceous–Paleogene boundary and became extinct immediately before or during the event. A very small number of dinosaur fossils have been found above the Cretaceous–Paleogene boundary, but they have been explained as reworked fossils , that is, fossils that have been eroded from their original locations then preserved in later sedimentary layers. Mosasaurs , plesiosaurs , pterosaurs and many species of plants and invertebrates also became extinct. Mammalian and bird clades passed through

912-539: The US Advisory Committee on Antarctic Names , in which the name "Antarctic Peninsula" was approved for the major peninsula of Antarctica , and the names Graham Land and Palmer Land for the northern and southern portions, respectively. The line dividing them is roughly 69 degrees south. Graham Land is named after Sir James R. G. Graham , First Lord of the Admiralty at the time of John Biscoe 's exploration of

960-601: The area Tierra de San Martín (Land of San Martin) and also calls the northern peninsula ( Trinity Peninsula ) Península Trinidad or Tierra de la Trinidad . Similarly, Chile calls the entire Antarctic Peninsula Tierra de O'Higgins (Land of O'Higgins). The interior of Graham Land is occupied by a series of plateaus, namely (north to south) Laclavère Plateau , Louis Philippe Plateau , Detroit Plateau , Herbert Plateau , Foster Plateau , Forbidden Plateau , Bruce Plateau , Avery Plateau and Hemimont Plateau . Late Cretaceous The Late Cretaceous (100.5–66 Ma )

1008-468: The boundary with few extinctions, and evolutionary radiation from those Maastrichtian clades occurred well past the boundary. Rates of extinction and radiation varied across different clades of organisms. Many scientists hypothesize that the Cretaceous–Paleogene extinctions were caused by catastrophic events such as the massive asteroid impact that caused the Chicxulub crater , in combination with increased volcanic activity , such as that recorded in

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1056-531: The cape was not adequately surveyed until 1902-03 when the Swedish expedition under Otto Nordenskjöld wintered in the area. Named by UK-APC after C. Wiman, who worked on the Seymour Island fossils collected by the Swedish expedition. 64°13′S 56°35′W  /  64.217°S 56.583°W  / -64.217; -56.583 . A cove at the northeast end of Seymour Island, southeast of Cape Wiman. The cove

1104-584: The climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Due to plate tectonics , the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia . India maintained

1152-542: The discoveries of the British Graham Land Expedition of 1934–1937, it was generally supposed to be an archipelago rather than a peninsula. The mountains of Graham Land are the last range of the American Cordillera , the almost continuous sequence of mountain ranges forming the western "backbone" of North America, Central America, South America and the Antarctic Peninsula . Argentina calls

1200-440: The eastern shore, and into an unnamed bay on the opposite shore east of Bodman Point. From Papua Beach to the northeastern extremity of the island runs a strip of deeply diffracted land. The southwestern portion of the island offers an appearance in marked contrast with the smooth surface of the northern portion. The southern half of the island has a peculiar ribbed appearance, being low and deeply dissected with many low hills between

1248-455: The erosive lines. Low perpendicular rock cliffs border the shore line but there are many landing places where the gorges slope gradually to the sea. A depot of provisions was placed by Nordenskjold in 1903 at a cairn in the valley behind Penguin Bay. A wooden plaque and rock cairn stand at Penguins Bay, on the southern coast of Seymour Island. The plaque was placed on 10 November 1903 by the crew of

1296-565: The island are the López de Bertodano Formation (Cretaceous to early Paleocene ), Sobral Formation and Cross Valley Formation (Paleocene) and La Meseta Formation (Eocene). Seymour Island has been referred to as the Rosetta Stone of Antarctic palaeontology , due to the unparalleled insight it provides into the geological and palaeontological history of the continent. In December 1892 when Norwegian Captain, Carl Anton Larsen landed his ship,

1344-646: The large predator niche in North America. They were also present in Asia, although were usually smaller and more primitive than the North American varieties. Pachycephalosaurs were also present in both North America and Asia. Dromaeosaurids shared the same geographical distribution, and are well documented in both Mongolia and Western North America. Additionally therizinosaurs (known previously as segnosaurs) appear to have been in North America and Asia. Gondwana held

1392-462: The larger key, James Ross Island , and its smaller, neighboring island, Vega Island . Seymour Island is sometimes called Marambio Island or Seymour-Marambio Island , taking its resident Argentine base as its namesake (see section, Base Antárctica Marambio , below). The US Defense Mapping Agency's Sailing Directions for Antarctica (1976) describes Seymour Island as follows: Seymour Island lies northeastward of Snow Hill Island , from which it

1440-636: The most common mammals in North America. In the southern hemisphere there was instead a more complex fauna of dryolestoids , gondwanatheres and other multituberculates and basal eutherians ; monotremes were presumably present, as was the last of the haramiyidans , Avashishta . Mammals, though generally small, ranged into a variety of ecological niches, from carnivores ( Deltatheroida ), to mollusc-eater ( Stagodontidae ), to herbivores (multituberculates, Schowalteria , Zhelestidae and Mesungulatidae ) to highly atypical cursorial forms ( Zalambdalestidae , Brandoniidae ). True placentals evolved only at

1488-438: The neighboring Snow Hill Island , surviving on penguins and seals . Ever since his voyage on the Jason , the island has been the subject of paleontological study. The Cretaceous-Paleogene boundary (K-Pg) crops out on Seymour Island in the upper levels of the López de Bertodano Formation . A small (but significant) iridium anomaly occurs at the boundary on Seymour Island, as at lower latitudes, thought to be fallout from

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1536-464: The north side of Seymour Island. The name appears on Argentine navy charts from 1957 and recalls J. López de Bertodano, chief engineer in the Argentine corvette Uruguay during the rescue of the shipwrecked SwedAE in 1903. Eastern features, from south to north, include: 64°19′S 56°43′W  /  64.317°S 56.717°W  / -64.317; -56.717 . A point located centrally along

1584-531: The numerous teleost fishes, which in turn evolved into new advanced and modern forms ( Neoteleostei ). Ichthyosaurs and pliosaurs , on the other hand, became extinct during the Cenomanian-Turonian anoxic event . Near the end of the Cretaceous Period, flowering plants diversified. In temperate regions, familiar plants like magnolias , sassafras , roses , redwoods , and willows could be found in abundance. The Cretaceous–Paleogene extinction event

1632-407: The open sea. Though primarily represented by azhdarchids , other forms like pteranodontids , tapejarids ( Caiuajara and Bakonydraco ), nyctosaurids and uncertain forms ( Piksi , Navajodactylus ) are also present. Historically, it has been assumed that pterosaurs were in decline due to competition with birds, but it appears that neither group overlapped significantly ecologically, nor

1680-437: The population of the base can grow to 180. The average temperatures on Seymour Island, as measured at Base Antárctica Marambio, are 1 °C (33.8 °F) during the summer and −21 °C (−5.8 °F) during the winter. In the wintertime, however, strong winds can lower the wind chill temperature feeling to as low as −60 °C (−76 °F) on exposed skin. On 9 February 2020, a temperature of 20.75 °C (69.3 °F)

1728-643: The same event. The site has been designated a Historic Site or Monument (HSM 60), following a proposal by Argentina to the Antarctic Treaty Consultative Meeting . Located in the island is the Marambio Base which is the main Argentine base in Antarctica operating an airfield ( ICAO SAWB) for wheeled landing the whole year. In winter the base has an average of 55 crew members, but in summer

1776-730: The south shore of Seymour Island. The point was possibly seen in 1843 by a British expedition under James Clark Ross , and was roughly charted by Captain Carl Anton Larsen who landed on the island in 1892 and 1893. Recharted by the SwedAE under Otto Nordenskjöld, 1901-04, who so named it because a large penguin colony was found there. 64°17′S 56°43′W  /  64.283°S 56.717°W  / -64.283; -56.717 . A ridge of exposed dark rock trending west-southwest – east.northeast, located 1.5 nautical miles (2.8 km; 1.7 mi) north of Penguin Point in central Seymour Island. The descriptive name "Filo Negro" (black ridge)

1824-433: The very end of the epoch; the same can be said for true marsupials . Instead, nearly all known eutherian and metatherian fossils belong to other groups. In the seas, mosasaurs suddenly appeared and underwent a spectacular evolutionary radiation. Modern sharks also appeared and penguin-like polycotylid plesiosaurs (3 meters long) and huge long-necked elasmosaurs (13 meters long) also diversified. These predators fed on

1872-421: The west part of Seymour Island. The feature was descriptively named "Quebrada Larga" (long valley) in Argentine geological reports and maps of 1978. The term valley has been substituted in place of "quebrada" in the approved name. 64°14′S 56°48′W  /  64.233°S 56.800°W  / -64.233; -56.800 . Rocky point which is situated centrally on the northwest coast of Seymour Island in

1920-599: The west side of Graham Land in 1832. It is claimed by Argentina (as part of Argentine Antarctica ), Britain (as part of the British Antarctic Territory ) and Chile (as part of the Chilean Antarctic Territory ). Graham Land is the closest part of Antarctica to South America. Thus it is the usual destination for small ships taking paying visitors on Antarctic trips from South America . (Larger ships are not allowed to disembark passengers.) Until

1968-609: The world in a listing published in October 2022. The organisation defines an 'IUGS Geological Heritage Site' as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.' Download coordinates as: Western features, from south to north, include: 64°19′S 56°54′W  /  64.317°S 56.900°W  / -64.317; -56.900 . The southwest point of Seymour Island. The cape

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2016-537: Was a large-scale mass extinction of animal and plant species in a geologically short period of time, approximately 66  million years ago (Ma). It is widely known as the K–T extinction event and is associated with a geological signature, usually a thin band dated to that time and found in various parts of the world, known as the Cretaceous–Paleogene boundary (K–T boundary). K is the traditional abbreviation for

2064-698: Was applied to this feature in Argentine geological reports on the island in 1978. The approved name, jointly recommended by the United States Advisory Committee on Antarctic Names (US-ACAN) and the UK Antarctic Place-Names Committee (UK-APC) in 1991, avoids duplication with Black Ridge in the Deep Freeze Range . 64°16′S 56°42′W  /  64.267°S 56.700°W  / -64.267; -56.700 . A valley 2 nautical miles (3.7 km; 2.3 mi) long in

2112-424: Was called "Fossil Bay" or "Bahia Fósiles" by United States Antarctic Research Program (USARP) and Argentine researchers because of fossils found here in 1982. The generic term bight is considered appropriate to this feature 64°17′S 56°49′W  /  64.283°S 56.817°W  / -64.283; -56.817 . A valley 2 nautical miles (3.7 km; 2.3 mi) long, trending northeast-southwest in

2160-563: Was named "Caleta Oviedo" in 1979 after an Argentine sailor who died in the Antarctic. Applied by the names commission, Argentine Ministry of Defense. Graham Land Graham Land is the portion of the Antarctic Peninsula that lies north of a line joining Cape Jeremy and Cape Agassiz . This description of Graham Land is consistent with the 1964 agreement between the British Antarctic Place-names Committee and

2208-406: Was named "Pinguinbucht" (Penguin Bay) from the large penguin rookery observed there by the SwedAE, 1901-04. The term bight is considered appropriate for this feature. 64°13′S 56°38′W  /  64.217°S 56.633°W  / -64.217; -56.633 . A low, rocky cape marking the north extremity of Seymour Island. Probably first seen by Sir James Clark Ross in January 1843, but

2256-681: Was named by the command of the Argentine ship Chiriguano of the Argentine Antarctic Expedition , 1953-54, after Guardiamarina (Midshipman) Lamas, of the Argentine Navy, who died aboard the trawler Fournier off Tierra del Fuego in September 1949. 64°18′S 56°52′W  /  64.300°S 56.867°W  / -64.300; -56.867 . A shallow recession in the north coast of Seymour Island, 1 nautical mile (1.9 km; 1.2 mi) north-northeast of Cape Lamas. The feature

2304-607: Was recorded on the island. However, on 1 July 2021, the World Meteorological Organization invalidated the reading because based on the analysis of the data, the air temperature was recorded in non-standard conditions, leading to bias and errors in the temperature sensor and readings. The rocks making up Seymour Island date mainly from the Late Cretaceous to the Eocene . Successively younger rock formations found on

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