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87-736: Before the Kurile Lake caldera formed, the Pauzhetka caldera was active during the Pleistocene , and was the origin of the Golygin ignimbrite at 443,000 ± 8,000 years old. The Kurile Lake caldera erupted 41,500 years ago, and another small eruption occurred between 9,000 and 10,000 years ago; then in 6460–6414 BCE , a very large eruption took place, forming the present-day caldera and the Kurile Lake ignimbrite and depositing ash as far as 1,700 kilometres (1,100 mi) away. This eruption has

174-418: A 1,500-year lull in volcanic activity allowed the deposition of soils in the area. A minor eruption occurred at Kurile Lake between 9,000 and 10,000 years ago, resulting in the deposition of tephra north of the caldera. This tephra is formed by gray fine ash and lapilli consisting of dacitic pumice. Other volcanoes also left several tephra deposits. Soils formed after the caldera forming eruptions also contain

261-611: A change from low-amplitude glacial cycles with a dominant periodicity of 41,000 years to asymmetric high-amplitude cycles dominated by a periodicity of 100,000 years. However, a 2020 study concluded that ice age terminations might have been influenced by obliquity since the Mid-Pleistocene Transition, which caused stronger summers in the Northern Hemisphere . Glaciation in the Pleistocene

348-574: A deviation from today's annual mean temperature, taken as zero. This sort of graph is based on another isotope ratio versus time. Ratios are converted to a percentage difference from the ratio found in standard mean ocean water (SMOW). The graph in either form appears as a waveform with overtones . One half of a period is a Marine isotopic stage (MIS). It indicates a glacial (below zero) or an interglacial (above zero). Overtones are stadials or interstadials. According to this evidence, Earth experienced 102 MIS stages beginning at about 2.588 Ma BP in

435-421: A few regions had been studied and the names were relatively few. Today the geologists of different nations are taking more of an interest in Pleistocene glaciology. As a consequence, the number of names is expanding rapidly and will continue to expand. Many of the advances and stadials remain unnamed. Also, the terrestrial evidence for some of them has been erased or obscured by larger ones, but evidence remains from

522-437: A number of ash layers by volcanoes both near and far. Volcanic activity occurred at Ilinsky volcano after the caldera forming eruption until 1901, and the similarity between Ilinsky and Kurile Lake rocks indicate that the activities of the two centers are related. Diky Greben formed less than 100 years after the formation of the caldera and was last active 1600 BP . A number of other lava domes and pyroclastic cones formed inside

609-417: A ring vent. Fumaroles formed as the ignimbrite overran rivers. Some post-eruption alteration of the ignimbrite deposits also took place. In the lake itself, the ignimbrite is about 400 metres (1,300 ft) thick. The pumice deposits have been affected by erosion and possibly by fumarolic activity, forming structures resembling overturned boats that were named “Khutk's boats” by native settlers. Ash from

696-578: A team of Russian scientists in collaboration with Princeton University announced that they had brought two female nematodes frozen in permafrost , from around 42,000 years ago, back to life. The two nematodes, at the time, were the oldest confirmed living animals on the planet. The evolution of anatomically modern humans took place during the Pleistocene. At the beginning of the Pleistocene Paranthropus species were still present, as well as early human ancestors, but during

783-463: A volume of 14.6 cubic kilometres (3.5 cu mi) and a catchment of 392 square kilometres (151 sq mi) and is surrounded by steep shores. Water remains in the lake for about eighteen years. In June 2011, a water temperature of 1.9 °C (35.4 °F) was measured. The lake waters are oligotrophic . The Ozernaya River drains the lake to the Sea of Okhotsk . Reports in 1923 indicate that

870-586: A volume of 140–170 cubic kilometres (34–41 cu mi), making it a VEI-7 -class eruption and one of the largest during the Holocene . Subsequently, the volcanoes Diky Greben and Ilinsky grew around the caldera; as of 2024, the most recent eruption from Ilinsky was in 1911. The caldera is filled by a lake with an area of 76 square kilometres (29 sq mi), and a maximum depth of 316 metres (1,037 ft). The largest sockeye salmon stocks in Asia live in

957-477: Is 81 metres (266 ft), this lake hosts a cryptodepression of 235 metres (771 ft). The southern basin is deeper than the northern basin (300 metres (980 ft) against the 200 metres (660 ft) of the northern basin) and is a Holocene caldera. The nature of the northern basin is less clear; Bondarenko in 1991 supposed that it was an older, separate caldera which he named Ilinsky, but Braitseva et al. 1997 and Ponomareva et al. 2004 consider both to be

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1044-781: Is estimated that, at maximum glacial extent, 30% of the Earth's surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America , and several hundred in Eurasia . The mean annual temperature at the edge of the ice was −6 °C (21 °F); at the edge of the permafrost, 0 °C (32 °F). Each glacial advance tied up huge volumes of water in continental ice sheets 1,500 to 3,000 metres (4,900–9,800 ft) thick, resulting in temporary sea-level drops of 100 metres (300 ft) or more over

1131-624: Is included in the Eastern Volcanic Zone of Kamchatka, 200 kilometres (120 mi) away from the trench. It is one of the two or three volcanic zones of Kamchatka, the other ones being the Central Depression and the Sredinny Range . Only the first two have had historical activity. The neighbouring volcano Ilinsky was active in 1911, and Zheltovsky was active in 1923. Hydrothermal activity may still be ongoing in

1218-459: Is no systematic correspondence between pluvials to glacials, however. Moreover, regional pluvials do not correspond to each other globally. For example, some have used the term "Riss pluvial" in Egyptian contexts. Any coincidence is an accident of regional factors. Only a few of the names for pluvials in restricted regions have been stratigraphically defined. The sum of transient factors acting at

1305-688: Is still a magma chamber beneath Kurile Lake at a depth of about 4 kilometres (2.5 mi). This magma chamber is about 10 kilometres (6.2 mi) wide. The Pacific Plate subducts at a pace of about 8 centimetres per year (3.1 in/year) beneath the Okhotsk Plate and Asian Plate . This subduction is responsible for the Kamchatka-Kuril Trench as well as for volcanism in Kamchatka. The Wadati-Benioff Zone lies about 100 kilometres (62 mi) beneath Kurile Lake. Kurile Lake

1392-522: Is the geological epoch that lasted from c.  2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations . Before a change was finally confirmed in 2009 by the International Union of Geological Sciences , the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of

1479-415: Is the largest known Holocene eruption in Kamchatka. Tephra from this eruption has been found in southern Kamchatka and also Magadan in Asia. The total volume of the Kurile Lake caldera forming eruption is about 140–170 cubic kilometres (34–41 cu mi), corresponding to a volcanic explosivity index of 7 and comparable to the 1815 eruption of Tambora . Other volcanoes with such large eruptions during

1566-659: The Alpine ice sheet on the Alps . Scattered domes stretched across Siberia and the Arctic shelf. The northern seas were ice-covered. South of the ice sheets large lakes accumulated because outlets were blocked and the cooler air slowed evaporation. When the Laurentide Ice Sheet retreated, north-central North America was completely covered by Lake Agassiz . Over a hundred basins, now dry or nearly so, were overflowing in

1653-656: The Chersky Range in eastern Siberia . It also includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge . The western edge is a triple junction plate boundary with the North American plate and Nubian plate at the seismically active Azores triple junction extending northward along the Mid-Atlantic Ridge towards Iceland . Ridges like

1740-529: The ICS timescale, the Pleistocene is divided into four stages or ages , the Gelasian , Calabrian , Chibanian (previously the unofficial "Middle Pleistocene"), and Upper Pleistocene (unofficially the "Tarantian"). In addition to these international subdivisions, various regional subdivisions are often used. In 2009 the International Union of Geological Sciences (IUGS) confirmed a change in time period for

1827-657: The Isthmus of Panama , causing a faunal interchange between the two regions and changing ocean circulation patterns, with the onset of glaciation in the Northern Hemisphere occurring around 2.7 million years ago. During the Early Pleistocene (2.58–0.8 Ma), archaic humans of the genus Homo originated in Africa and spread throughout Afro-Eurasia . The end of the Early Pleistocene is marked by

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1914-677: The Laurentide Ice Sheet . Charles Lyell introduced the term "Pleistocene" in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today. This distinguished it from the older Pliocene Epoch , which Lyell had originally thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" ('most new' or 'newest') from the Greek πλεῖστος ( pleīstos ) 'most' and καινός ( kainós ( Latinized as cænus ) 'new'). This contrasts with

2001-615: The Mid-Pleistocene Transition , with the cyclicity of glacial cycles changing from 41,000-year cycles to asymmetric 100,000-year cycles, making the climate variation more extreme. The Late Pleistocene witnessed the spread of modern humans outside of Africa as well as the extinction of all other human species. Humans also spread to the Australian continent and the Americas for the first time, co-incident with

2088-662: The Ruwenzori Range in east and central Africa were larger. Glaciers existed in the mountains of Ethiopia and to the west in the Atlas Mountains . In the northern hemisphere, many glaciers fused into one. The Cordilleran Ice Sheet covered the North American northwest; the east was covered by the Laurentide . The Fenno-Scandian ice sheet rested on northern Europe , including much of Great Britain;

2175-602: The Sea of Okhotsk then south through Sakhalin Island and Hokkaido to the triple junction in the Japan Trench . But this simple view has been successfully challenged by more recent research. During the 1970s, Japan was thought to be located on the Eurasian plate at a quadruple junction with the North American plate when the eastern boundary of the North American plate was drawn through southern Hokkaido . New research in

2262-477: The last glacial period ended about 10,000 years ago. Over 11 major glacial events have been identified, as well as many minor glacial events. A major glacial event is a general glacial excursion, termed a "glacial." Glacials are separated by "interglacials". During a glacial, the glacier experiences minor advances and retreats. The minor excursion is a "stadial"; times between stadials are "interstadials". These events are defined differently in different regions of

2349-599: The woolly rhinoceros , various giraffids , such as the Sivatherium ; ground sloths , Irish elk , cave lions , cave bears , Gomphotheres , American lions , dire wolves , and short-faced bears , began late in the Pleistocene and continued into the Holocene. Neanderthals also became extinct during this period. At the end of the last ice age, cold-blooded animals, smaller mammals like wood mice , migratory birds, and swifter animals like whitetail deer had replaced

2436-569: The 1990s supported that the Okhotsk microplate was independent from the North American plate and a boundary with the Amurian microplate , sometimes described as "a division within the Eurasian plate" with an unknown western boundary. All volcanic eruptions in Iceland, such as the 1973 eruption of Eldfell , the 1783 eruption of Laki and the 2010 eruption of Eyjafjallajökull , are caused by

2523-569: The Early Pleistocene Gelasian . Early Pleistocene stages were shallow and frequent. The latest were the most intense and most widely spaced. By convention, stages are numbered from the Holocene, which is MIS1. Glacials receive an even number and interglacials receive an odd number. The first major glacial was MIS2-4 at about 85–11 ka BP. The largest glacials were 2, 6, 12, and 16. The warmest interglacials were 1, 5, 9 and 11. For matching of MIS numbers to named stages, see under

2610-409: The Earth's surface is cyclical: climate, ocean currents and other movements, wind currents, temperature, etc. The waveform response comes from the underlying cyclical motions of the planet, which eventually drag all the transients into harmony with them. The repeated glaciations of the Pleistocene were caused by the same factors. The Mid-Pleistocene Transition , approximately one million years ago, saw

2697-690: The Eurasian plate with the Arabian plate in the East Anatolian Fault Zone . The boundary between the North American plate and the Eurasian plate in the area around Japan has been described as "shifty". There are different maps for it based on recent tectonics, seismicity and earthquake focal mechanism . The simplest plate geometry draws the boundary from the Nansen Ridge through a broad zone of deformation in North Asia to

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2784-550: The Holocene include Baitoushan , Crater Lake and Kikai . The caldera forming eruption commenced with a phreatoplinian eruption that generated deposits of fine ash. Several yellowish rhyolitic ignimbrites were erupted, reaching a thickness of over 50 metres (160 ft). These ignimbrites filled gullies around the lake and also reach thicknesses of several tens of centimeters in the Vychenkiya River and Unkanovich River valleys. This eruption phase occurred through

2871-420: The Kurile Lake caldera. This caldera has an area of about 45 square kilometres (17 sq mi), or 14 by 8 kilometres (8.7 mi × 5.0 mi). In that case, the ridge that separates the two basins may be a deposit left when earthquakes preceding the caldera-forming eruption caused Ilinsky volcano to collapse. The caldera collapse was controlled by faults that parallel the lake shores. Some islands in

2958-573: The Mid-Atlantic ridge form at a divergent plate boundary . They are located deep underwater and very difficult to study. Scientists know less about ocean ridges than they do the planets of the solar system. There is another triple junction where the Eurasian plate meets the Anatolian sub-plate and the Arabian plate . The Anatolian sub-plate is currently being squeezed by the collision of

3045-583: The North American and the Eurasian plates moving apart, which is a result of divergent plate boundary forces. The convergent boundary between the Eurasian plate and the Indian plate formed the Himalayas mountain range. The geodynamics of Central Asia is dominated by the interaction between the Eurasian plate and the Indian plate. In this area, many sub-plates or crust blocks have been recognized, which form

3132-479: The North American west. Lake Bonneville , for example, stood where Great Salt Lake now does. In Eurasia, large lakes developed as a result of the runoff from the glaciers. Rivers were larger, had a more copious flow, and were braided . African lakes were fuller, apparently from decreased evaporation. Deserts, on the other hand, were drier and more extensive. Rainfall was lower because of the decreases in oceanic and other evaporation. It has been estimated that during

3219-434: The Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. Radiocarbon dating is considered to be inaccurate beyond around 50,000 years ago. Marine isotope stages (MIS) derived from Oxygen isotopes are often used for giving approximate dates. Pleistocene non-marine sediments are found primarily in fluvial deposits , lakebeds, slope and loess deposits as well as in

3306-496: The Pleistocene's overall climate could be characterised as a continuous El Niño with trade winds in the south Pacific weakening or heading east, warm air rising near Peru , warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, and other El Niño markers. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places. It

3393-584: The Pleistocene, calderas, lava plateaus , and somma volcanoes like pre-Ilinsky stratovolcanoes formed in the area. One caldera that formed in the area is the Pauzhetka Caldera , of middle Pleistocene age. As of 2004, the possibility that a later caldera existed in the Pauzhetka caldera was considered. Kurile Lake is located in the eastern part of this Pauzhetka caldera, which has dimensions of 55 by 35 kilometres (34 mi × 22 mi). In

3480-503: The Pleistocene, changing the start date from 1.806 to 2.588 million years BP, and accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola GSSP . The start date has now been rounded down to 2.580 million years BP. The IUGS has yet to approve a type section , Global Boundary Stratotype Section and Point (GSSP), for the upper Pleistocene/Holocene boundary ( i.e.

3567-805: The Pleistocene, the East Antarctic Ice Sheet thinned by at least 500 meters, and that thinning since the Last Glacial Maximum is less than 50 meters and probably started after ca 14 ka. During the 2.5 million years of the Pleistocene, numerous cold phases called glacials ( Quaternary ice age ), or significant advances of continental ice sheets, in Europe and North America, occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter interglacials which lasted about 10,000–15,000 years. The last cold episode of

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3654-411: The Pleistocene, the plates upon which they sit probably having moved no more than 100 km (62 mi) relative to each other since the beginning of the period. In glacial periods, the sea level would drop by up to 120 m (390 ft) lower than today during peak glaciation, exposing large areas of the present continental shelf as dry land. According to Mark Lynas (through collected data),

3741-566: The Pliocene or Pleistocene and was most likely accompanied by the eruption of the 300–450-cubic-kilometre (72–108 cu mi) Golygino ignimbrite . The eruption of this ignimbrite occurred 443,000 ± 8000 years ago. Afterwards, a resurgent dome named the Kambalny ridge formed in the Pauzhetka structure, as well as a proto-Ilinsky volcano. The basement in the area is formed by Miocene-Pliocene sedimentary rocks and volcanic rocks . During

3828-512: The amounts released by Tambora in 1815 and by Huaynaputina in 1600. Two sulfate spikes identified in the GISP2 ice core of Greenland around 6470 and 6476 BC may be linked to the Kurile Lake eruption. The Kurile Lake eruption may have influenced the global climate . The eruption devastated the vegetation in southern Kamchatka, causing an ecological catastrophe. Close to Kurile Lake, all vegetation would have been wiped out, and deposits left by

3915-706: The appearance of Homo sapiens about 300,000 years ago. Artifacts associated with modern human behavior are unambiguously attested starting 40,000–50,000 years ago. According to mitochondrial timing techniques, modern humans migrated from Africa after the Riss glaciation in the Middle Palaeolithic during the Eemian Stage , spreading all over the ice-free world during the late Pleistocene. A 2005 study posits that humans in this migration interbred with archaic human forms already outside of Africa by

4002-527: The articles for those names. Both marine and continental faunas were essentially modern but with many more large land mammals such as Mammoths , Mastodons , Diprotodons , Smilodons , tigers , lions , Aurochs , short-faced bears , giant sloths , species within Gigantopithecus and others. Isolated landmasses such as Australia , Madagascar , New Zealand and islands in the Pacific saw

4089-585: The bulk of the eruption products of Kurile Lake. Minerals contained include plagioclase , orthopyroxene , clinopyroxene , magnetite , and hornblende , in decreasing order of importance. The ash becomes white away from the vent, while near-vent deposits are often yellow. Vegetation around the caldera consists mostly of bush and forest . At the edge of the lake there is no macrovegetation. Vegetation in Kamchatka overall consists mostly of alder bushes, pine , and stone birch . Along valleys, cottonwood and willow can be found as well. In 1998, Kurile Lake had

4176-425: The caldera by the caldera-forming eruption. The rim of the Kurile Lake caldera is best expressed at Ilinsky volcano and south and northwest thereof. Close to the lake, two Pleistocene caldera rims can be found and there may be more. The volcanoes Diky Greben, Ilinsky, Kambalny , Kosheleva , and Zheltovsky surround Kurile Lake. Diky Greben formed after the eruption of Kurile Lake. Gravimetry indicates that there

4263-449: The caldera shortly after the caldera-forming eruption. The caldera-forming eruption of Kurile Lake had a devastating effect on the surrounding area and had a noticeable effect far from the lake. A significant amount of gas was released during the eruption, including 3.7–4.2 billion metric tons of water , 43–49 million tons of chlorine , 8.6–9.8 million tons of fluorine , and 26–29 million tons of sulfur , comparable to

4350-477: The center of the Pauzhetka caldera lies a 650-metre (2,130 ft)-wide depression that covers an area of 25 by 20 kilometres (16 mi × 12 mi). Southern Kamchatka has been the site of explosive eruptions during history; the Ksudach volcano 50 kilometres (31 mi) north of Kurile Lake had five caldera forming eruptions during the Pleistocene and Holocene. The time period between 6400 and 6600 BCE

4437-424: The dominant cladocerans Daphnia longiremis . Other species as well as rotifers are also present; they constitute sources of food for sockeye salmons. A number of annelid species are also found, many of the species that are found in neighboring waters cannot be found in the lake. The chironomid midge Chaetocladius tatianae is endemic to the Kurile Lake watershed. Sockeye salmon fisheries are present at

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4524-618: The entire surface of the Earth. During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Zealand and Tasmania . The current decaying glaciers of Mount Kenya , Mount Kilimanjaro , and

4611-626: The eruption spread west-northwest of Kurile Lake, covering a total surface of over 2,000,000 square kilometres (770,000 sq mi). It can be found at large distances from the caldera; 1-millimetre-thick (0.04 in) layers have been found in the upper reaches of the Indigirka River , 1,700 kilometres (1,100 mi) away from Kurile Lake, and in the Oymyakon Plateau . Thicknesses still reach several centimeters in Magadan. In

4698-459: The eruption would have hampered the revegetation as well. In more favorable terrain where the volcanic deposits were quickly removed, some plants like Alnus fruticosa did survive and quickly resettled the terrain. Pleistocene The Pleistocene ( / ˈ p l aɪ s t ə ˌ s iː n , - s t oʊ -/ PLY -stə-seen, -⁠stoh- ; referred to colloquially as the Ice Age )

4785-782: The evolution of large birds and even reptiles such as the Elephant bird , moa , Haast's eagle , Quinkana , Megalania and Meiolania . The severe climatic changes during the Ice Age had major impacts on the fauna and flora. With each advance of the ice, large areas of the continents became depopulated, and plants and animals retreating southwards in front of the advancing glacier faced tremendous stress. The most severe stress resulted from drastic climatic changes, reduced living space, and curtailed food supply. A major extinction event of large mammals ( megafauna ), which included mammoths , mastodons , saber-toothed cats , glyptodons ,

4872-444: The extinction of most large-bodied animals in these regions. The aridification and cooling trends of the preceding Neogene were continued in the Pleistocene. The climate was strongly variable depending on the glacial cycle, with the sea levels being up to 120 metres (390 ft) lower than present at peak glaciation, allowing the connection of Asia and North America via Beringia and the covering of most of northern North America by

4959-414: The glacial range, which have their own glacial history depending on latitude, terrain and climate. There is a general correspondence between glacials in different regions. Investigators often interchange the names if the glacial geology of a region is in the process of being defined. However, it is generally incorrect to apply the name of a glacial in one region to another. For most of the 20th century, only

5046-454: The highest density of brown bears of Kamchatka , and possibly of the entirety of Russia. The lake is a nature reserve . The Kurile Lake caldera is filled by the Kurile crater lake, covering a surface area of 76 square kilometres (29 sq mi) to 77.1 square kilometres (29.8 sq mi). A lake existed already before the Kurile Lake caldera-forming eruption. The present-day lake has

5133-450: The historical terminology was established. Corresponding to the terms glacial and interglacial, the terms pluvial and interpluvial are in use (Latin: pluvia , rain). A pluvial is a warmer period of increased rainfall; an interpluvial is of decreased rainfall. Formerly a pluvial was thought to correspond to a glacial in regions not iced, and in some cases it does. Rainfall is cyclical also. Pluvials and interpluvials are widespread. There

5220-445: The immediately preceding Pliocene ("newer", from πλείων ( pleíōn , "more") and kainós ) and the immediately subsequent Holocene ("wholly new" or "entirely new", from ὅλος ( hólos , "whole") and kainós ) epoch , which extends to the present time. The Pleistocene has been dated from 2.580 million (±0.005) to 11,700 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. It covers most of

5307-402: The lake formed by slumping and others are volcanic cones; the “Heart of Alaid” (Serdtze Alaida) is a lava dome 300 metres (980 ft) high. A number of lava domes and pyroclastic cones are found in the lake. The Severnaya bay may be an explosion crater . Lava flows from Ilinsky extend into the lake. Ring faults , partially buried by alluvial fans and landslides , limit the caldera in

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5394-454: The lake is formed by a flat basin; canyons cut into the slopes of the western side of the lake, where the Ozernaya and Kumnynk rivers open into the lake. The Etamynk and Khakytsin rivers conversely have formed an alluvial fan . The maximum depth of the lake is 316 metres (1,037 ft), with an average depth of 195 metres (640 ft) or 180 metres (590 ft). Since the surface elevation

5481-490: The lake was formerly up to 50 metres (160 ft) higher than today, possibly because lava flows dammed its outlet. At least two other shorelines are found 15–20 metres (49–66 ft) above the current water level. The caldera lake may have suffered a catastrophic outburst flood in the past. Diatoms form most of the phytoplankton , with Cyclotella , Melosira , Stephanodiskus , and Synedra . Dominant copepod species in summer 2011 include Cyclops scutifer and

5568-477: The lake. Kurile Lake is found in the southern part of the Kamchatka Peninsula, in a rugged volcanic landscape. The region was not always part of the Kamchatka Peninsula; during the middle Pleistocene, it was an island. Georg Wilhelm Steller visited the area in 1740–1743. Kurile Lake is formed by two basins, which are separated by a 150-metre-wide (490 ft) subaqueous ridge. The center part of

5655-567: The lake. The oldest volcanoes of the Pauzhetka structure may be of Oligocene - Miocene age; during that time, the area was in the sea. The sedimentary Paratunka Formation and the Kurilsky complex were deposited during that time; they are exposed east and southwest of Kurile Lake. About 600–650 cubic kilometres (140–160 cu mi) of basaltic rocks were erupted during the Miocene- Pliocene . The Pauzhetka depression formed during

5742-459: The lake. A large landslide forms Glinyany Peninsula in the southeastern shore of the lake. Post-caldera activity has formed some islands in the lake and the Diky Greben volcano. Both Glinyany Peninsula and the post-caldera lava domes (Chayachii, Serdtze Alaida, Tugumynk) were affected by slumping. Approximately 120–160 metres (390–520 ft) of sediment and volcanites bury the deposits left in

5829-401: The lake. All these deposits were formed by the same event. Subsequently, a short eruption of lapilli and pumice consisting of dacite and rhyolite occurred, most of it falling towards the northwest; their thickness reaches 20 centimetres (7.9 in) north of the lake. Some basaltic scoria was also deposited during this phase. At this point, the vent had emerged above the water level and

5916-609: The lake. The lake is a major nursery for this species of fish. The number of fish in the lake ranges from 260,000 to over 6 million. The stocks found at Kurile Lake are the largest in Asia . Fishing of the salmon of the Ozernaya River has been regulated to allow their reproduction and to conserve bear populations. The lake is part of the Kamchatka National Reserve. The idea that pumice around Kurile Lake

6003-622: The large amounts of material moved about by glaciers. Less common are cave deposits, travertines and volcanic deposits (lavas, ashes). Pleistocene marine deposits are found primarily in shallow marine basins mostly (but with important exceptions) in areas within a few tens of kilometres of the modern shoreline. In a few geologically active areas such as the Southern California coast, Pleistocene marine deposits may be found at elevations of several hundred metres. The modern continents were essentially at their present positions during

6090-399: The late Pleistocene, incorporating archaic human genetic material into the modern human gene pool. Asian Plate The Eurasian plate is a tectonic plate that includes most of Eurasia (a landmass consisting of the traditional continents of Asia and Europe ), with the notable exceptions of the Arabian Peninsula , the Indian subcontinent , and the area east of

6177-415: The latest period of repeated glaciation , up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9700 BCE (11,700 calendar years BP). The end of the Younger Dryas is the official start of the current Holocene Epoch . Although it is considered an epoch, the Holocene is not significantly different from previous interglacial intervals within the Pleistocene. In

6264-470: The lower Palaeolithic they disappeared, and the only hominin species found in fossilic records is Homo erectus for much of the Pleistocene. Acheulean lithics appear along with Homo erectus , some 1.8 million years ago, replacing the more primitive Oldowan industry used by A. garhi and by the earliest species of Homo . The Middle Paleolithic saw more varied speciation within Homo , including

6351-478: The megafauna and migrated north. Late Pleistocene bighorn sheep were more slender and had longer legs than their descendants today. Scientists believe that the change in predator fauna after the late Pleistocene extinctions resulted in a change of body shape as the species adapted for increased power rather than speed. The extinctions hardly affected Africa but were especially severe in North America where native horses and camels were wiped out. In July 2018,

6438-408: The more mafic deposits. These mafic ignimbrites are not found around the entire lake, indicating that the magma chamber was asymmetric or its contents were erupted in an asymmetric fashion. The ignimbrite contains remnants of vegetation, accretionary structures formed when the ignimbrite interacted with water, and breccia probably formed when conditions at the vent changed, involving the formation of

6525-452: The northern Kuriles , the thickness reaches several tens of centimeters. This ash is found in drilling cores in the Sea of Okhotsk. Coignimbrite ash formed when the ignimbrites reached the sea. In terms of composition, it ranges from rhyolite to dacite and is poor in potassium. The ash is an important tephrochronological marker and has been found as far away as Greenland . Before the eruption,

6612-478: The period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology . The name is a combination of Ancient Greek πλεῖστος ( pleîstos ) 'most' and καινός ( kainós ; Latinized as cænus ) 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by

6699-417: The ratio of O to O (two isotopes of oxygen ) by mass (measured by a mass spectrometer ) present in the calcite of oceanic core samples is used as a diagnostic of ancient ocean temperature change and therefore of climate change. Cold oceans are richer in O , which is included in the tests of the microorganisms ( foraminifera ) contributing the calcite. A more recent version of

6786-461: The recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. Formerly, the boundary between the two epochs was drawn at the time when the foraminiferal species Hyalinea baltica first appeared in the marine section at La Castella, Calabria, Italy. However, the revised definition of the Quaternary , by pushing back the start date of

6873-407: The sampling process makes use of modern glacial ice cores. Although less rich in O than seawater, the snow that fell on the glacier year by year nevertheless contained O and O in a ratio that depended on the mean annual temperature. Temperature and climate change are cyclical when plotted on a graph of temperature versus time. Temperature coordinates are given in the form of

6960-649: The sole factor responsible for the variations in climate since they explain neither the long-term cooling trend over the Plio-Pleistocene nor the millennial variations in the Greenland Ice Cores known as Dansgaard-Oeschger events and Heinrich events. Milankovitch pacing seems to best explain glaciation events with periodicity of 100,000, 40,000, and 20,000 years. Such a pattern seems to fit the information on climate change found in oxygen isotope cores. In oxygen isotope ratio analysis, variations in

7047-421: The study of cyclical climate changes. The glacials in the following tables show historical usages, are a simplification of a much more complex cycle of variation in climate and terrain, and are generally no longer used. These names have been abandoned in favour of numeric data because many of the correlations were found to be either inexact or incorrect and more than four major glacials have been recognised since

7134-648: The upper boundary). The proposed section is the North Greenland Ice Core Project ice core 75° 06' N 42° 18' W. The lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama (C2r) chronozone , isotopic stage 103. Above this point there are notable extinctions of the calcareous nannofossils : Discoaster pentaradiatus and Discoaster surculus . The Pleistocene covers

7221-543: Was a series of glacials and interglacials, stadials and interstadials, mirroring periodic climate changes. The main factor at work in climate cycling is now believed to be Milankovitch cycles . These are periodic variations in regional and planetary solar radiation reaching the Earth caused by several repeating changes in the Earth's motion. The effects of Milankovitch cycles were enhanced by various positive feedbacks related to increases in atmospheric carbon dioxide concentrations and Earth's albedo. Milankovitch cycles cannot be

7308-460: Was especially active, with caldera-forming eruptions including the one that formed Kurile Lake. Kurile Lake is not the only volcano in Kamchatka with major explosive eruptions during the Holocene that exceeded VEI 5 ; three other such eruptions occurred at Ksudach volcano and one at Karymsky volcano. Volcanic rocks of Kurile Lake range from basaltic andesite to rhyolite . They contain small-to-medium amounts of potassium . Rhyolite makes up

7395-609: Was formed by an eruption in the area of the lake was first suggested by Boris Piip in 1947. Later research identified this pumice as the product of the caldera-forming eruption, although some skepticism remains, which considers this pumice as the product of fissure eruptions . An earlier Pleistocene caldera-forming eruption took place 41,500 years ago; ash deposits from this eruption are found as far away as Magadan , 1,000 kilometres (620 mi) away from Kurile Lake, and possibly Lake El′gygytgyn . The Kurile Lake caldera forming eruption, also known as "KO", occurred in 6460–6414 BCE . It

7482-492: Was generating an eruption column that deposited ash over southern Kamchatka. Eventually, the vent widened and caused the eruption column to collapse. At this point, pyroclastic flows formed and deposited the Kurile Lake ignimbrite. Reaching a thickness of 150 metres (490 ft) close to the lake, it filled valleys, overran plateaus and ridges, and reached both the Pacific Ocean and the Sea of Okhotsk . The ignimbrite

7569-403: Was highly mobile, overrunning high topographic obstacles and flowing along valleys in a complex flow pattern. The ignimbrite covered a total surface area of 1,800–1,900 square kilometres (690–730 sq mi). This ignimbrite consists of rocks ranging from basaltic andesite to rhyolite with colors ranging from white to dark. Unusually for such mixed-composition ignimbrites, the rhyolites overlie

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