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23-578: The San Ramón is a thrust fault with vertical slippage which has caused the formation of the Sierra de Ramón, a 25 kilometer long mountain chain with a maximum height of 3249 meters above sea level. This range has moved noticeably in the last 10 million years, and grown notably during the recent Quaternary period, which makes it a geologically active fault. It shows traces of deformation on the order of 0,02 mm/year, making it capable of producing significant earthquakes, such as in 1575 and 1647 . The fault represents

46-643: A boundary marker, it has since been identified in strata 4m below the GSSP. However, no other fossil is known that would be preferable. There is no radiometrically datable bed at the boundary at Fortune Head, but there is one slightly above the boundary in similar beds nearby. These factors have led some geologists to suggest that this GSSP is in need of reassigning. Because defining a GSSP depends on finding well-preserved geologic sections and identifying key events, this task becomes more difficult as one goes farther back in time. Before 630 million years ago, boundaries on

69-408: A discontinuity in the rocky subsoil which modifies its characteristics by fragmenting the rock, generating fault ruptures, dislocation and fracturing of blocks in the immediate surroundings, and even generating hot springs which chemically alter the rock. This tectonics article is a stub . You can help Misplaced Pages by expanding it . This Santiago Metropolitan Region location article

92-538: Is a stub . You can help Misplaced Pages by expanding it . Quaternary The Quaternary ( / k w ə ˈ t ɜːr n ə r i , ˈ k w ɒ t ər n ɛr i / kwə- TUR -nə-ree, KWOT -ər-nerr-ee ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of

115-403: Is set at the first appearance of a complex trace fossil Treptichnus pedum that is found worldwide. The Fortune Head GSSP is unlikely to be washed away or built over. Nonetheless, Treptichnus pedum is less than ideal as a marker fossil as it is not found in every Cambrian sequence, and it is not assured that it is found at the same level in every exposure. In fact, further eroding its value as

138-562: The 101 stages that need a GSSP have a ratified GSSP. A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the ICS . The following list summarizes the criteria: Once a GSSP boundary has been agreed upon, a 'golden spike' is driven into the geologic section to mark the precise boundary for future geologists (though in practice the 'spike' need neither be golden nor an actual spike). As such, GSSPs are also sometimes referred to as golden spikes . The first stratigraphic boundary

161-465: The 1970s, the International Commission on Stratigraphy (ICS) tried to make a single geologic time scale based on GSSP 's, which could be used internationally. The Quaternary subdivisions were defined based on biostratigraphy instead of paleoclimate . This led to the problem that the proposed base of the Pleistocene was at 1.805 million years ago, long after the start of the major glaciations of

184-513: The Alps. This idea was initially disputed by another Swiss scientist, Louis Agassiz , but when he undertook to disprove it, he ended up affirming his colleague's hypothesis. A year later, Agassiz raised the hypothesis of a great glacial period that would have had long-reaching general effects. This idea gained him international fame and led to the establishment of the Glacial Theory. In time, thanks to

207-598: The ICS. The Quaternary is typically defined by the Quaternary glaciation , the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused. In 1759 Giovanni Arduino proposed that the geological strata of northern Italy could be divided into four successive formations or "orders" ( Italian : quattro ordini ). The term "quaternary"

230-455: The Quaternary represents the time during which recognisable humans existed. Over this geologically short time period there has been relatively little change in the distribution of the continents due to plate tectonics . The Quaternary geological record is preserved in greater detail than that for earlier periods. The major geographical changes during this time period included the emergence of

253-459: The glacial period ended about 11,700 years ago. Modern humans evolved about 315,000 years ago. During the Quaternary Period, mammals, flowering plants, and insects dominated the land. GSSP A Global Boundary Stratotype Section and Point ( GSSP ), sometimes referred to as a golden spike , is an internationally agreed upon reference point on a stratigraphic section which defines

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276-562: The lower boundary of a stage on the geologic time scale . The effort to define GSSPs is conducted by the International Commission on Stratigraphy , a part of the International Union of Geological Sciences . Most, but not all, GSSPs are based on paleontological changes. Hence GSSPs are usually described in terms of transitions between different faunal stages , though far more faunal stages have been described than GSSPs. The GSSP definition effort commenced in 1977. As of 2024, 79 of

299-595: The northern hemisphere. The ICS then proposed to abolish use of the name Quaternary altogether, which appeared unacceptable to the International Union for Quaternary Research (INQUA). In 2009, it was decided to make the Quaternary the youngest period of the Cenozoic Era with its base at 2.588 mya and including the Gelasian Stage, which was formerly considered part of the Neogene Period and Pliocene Epoch. This

322-600: The periodic flash flooding of Scablands of the American Northwest by glacial water. The current extent of Hudson Bay , the Great Lakes and other major lakes of North America are a consequence of the Canadian Shield 's readjustment since the last ice age; different shorelines have existed over the course of Quaternary time. The climate was one of periodic glaciations with continental glaciers moving as far from

345-463: The poles as 40 degrees latitude . Glaciation took place repeatedly during the Quaternary Ice age  – a term coined by Schimper in 1839 that began with the start of the Quaternary about 2.58 Mya and continues to the present day. In 1821, a Swiss engineer, Ignaz Venetz , presented an article in which he suggested the presence of traces of the passage of a glacier at a considerable distance from

368-596: The refinement of geology, it has been demonstrated that there were several periods of glacial advance and retreat and that past temperatures on Earth were very different from today. In particular, the Milankovitch cycles of Milutin Milankovitch are based on the premise that variations in incoming solar radiation are a fundamental factor controlling Earth's climate. During this time, substantial glaciers advanced and retreated over much of North America and Europe, parts of South America and Asia, and all of Antarctica. There

391-470: The start of the Quaternary at the onset of Northern Hemisphere glaciation approximately 2.6 million years ago ( mya ). Prior to 2009, the Pleistocene was defined to be from 1.805 million years ago to the present, so the current definition of the Pleistocene includes a portion of what was, prior to 2009, defined as the Pliocene . Quaternary stratigraphers usually worked with regional subdivisions. From

414-657: The straits of Bosphorus and Skagerrak during glacial epochs, which respectively turned the Black Sea and Baltic Sea into fresh water lakes, followed by their flooding (and return to salt water) by rising sea level; the periodic filling of the English Channel , forming a land bridge between Britain and the European mainland; the periodic closing of the Bering Strait , forming the land bridge between Asia and North America ; and

437-681: The twelve periods of the Phanerozoic eon. It follows the Neogene Period and spans from 2.58 million years ago to the present. The Quaternary Period is divided into two epochs: the Pleistocene (2.58 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today); a proposed third epoch, the Anthropocene , was rejected in 2024 by IUGS , the governing body of

460-563: Was a major extinction of large mammals globally during the Late Pleistocene Epoch. Many forms such as sabre-toothed cats , mammoths , mastodons , glyptodonts , etc., became extinct worldwide. Others, including horses , camels and American cheetahs became extinct in North America . The Great Lakes formed and giant mammals thrived in parts of North America and Eurasia not covered in ice. These mammals became extinct when

483-587: Was defined in 1972 by identifying the Silurian - Devonian boundary with a bronze plaque at a locality called Klonk , northeast of the village of Suchomasty in the Czech Republic . The Precambrian - Cambrian boundary GSSP at Fortune Head , Newfoundland is a typical GSSP. It is accessible by paved road and is set aside as a nature preserve . A continuous section is available from beds that are clearly Precambrian into beds that are clearly Cambrian. The boundary

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506-404: Was introduced by Jules Desnoyers in 1829 for sediments of France 's Seine Basin that clearly seemed to be younger than Tertiary Period rocks . The Quaternary Period follows the Neogene Period and extends to the present. The Quaternary covers the time span of glaciations classified as the Pleistocene , and includes the present interglacial time-period, the Holocene . This places

529-470: Was later revised to 2.58 mya. The Anthropocene was proposed as a third epoch as a mark of the anthropogenic impact on the global environment starting with the Industrial Revolution , or about 200 years ago. The Anthropocene was rejected as a geological epoch in 2024 by the International Union of Geological Sciences (IUGS), the governing body of the ICS. The 2.58 million years of

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