|
Aptian Extinctions
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous. The Aptian partly overlaps the upper part of the Western European Urgonian Stage. The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous Period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years. The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.Archangelsky, Sergio.The Ticó Flora (Patagonia) and the Aptian Extinction Event" ''Acta Paleobotanica'' 41(2), 2001, pp. 115-22. Stratigraphic definitions The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its cry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Commission On Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes referred to unofficially as the "International Stratigraphic Commission", is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, stratigraphical, geology, geological, and chronology, geochronological matters on a global scale. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working committee, working subcommittee, which meets far more regularly than the quadrennial meetings scheduled by the IUGS, when it meets as a congress or committee, membership of the whole. Aims One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontology, paleontological and geobiology, geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic Column
A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest rocks on the bottom and the youngest on top. In areas that are more geologically complex, such as those that contain intrusive rocks, faults, and/or metamorphism, stratigraphic columns can still indicate the relative locations of these units with respect to one another. However, in these cases, the stratigraphic column must either be a structural column, in which the units are stacked with respect to how they are observed in the field to have been moved by the faults, or a time column, in which the units are stacked in the order in which they were formed. Stratigraphy is a branch of geology that concerns the order and relative position of geologic strata and their relationship to the geologic time scale. The relative time sequencing req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Provence
Provence (, , , , ; oc, Provença or ''Prouvènço'' , ) is a geographical region and historical province of southeastern France, which extends from the left bank of the lower Rhône to the west to the Italian border to the east; it is bordered by the Mediterranean Sea to the south. It largely corresponds with the modern administrative region of Provence-Alpes-Côte d'Azur and includes the departments of Var, Bouches-du-Rhône, Alpes-de-Haute-Provence, as well as parts of Alpes-Maritimes and Vaucluse.''Le Petit Robert, Dictionnaire Universel des Noms Propres'' (1988). The largest city of the region and its modern-day capital is Marseille. The Romans made the region the first Roman province beyond the Alps and called it ''Provincia Romana'', which evolved into the present name. Until 1481 it was ruled by the Counts of Provence from their capital in Aix-en-Provence, then became a province of the Kings of France. While it has been part of France for more than 500 years, it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apt, Vaucluse
Apt (; Provençal Occitan: ''At / Ate'' in both classical and Mistralian norms) is a commune in the Vaucluse department in the Provence-Alpes-Côte d'Azur region in southeastern France. It lies on the left bank of the Calavon, east of Avignon. It is the principal town of the Luberon mountains. The town is known for defining the Aptian age of the Early Cretaceous. Geography Apt lies north of Aix-en-Provence and the river Durance, in the valley of the river Calavon, (also called the Coulon), and at the foot of the north-facing slopes of the Luberon mountain. Geological age Apt is the etymological source of the Aptian, an age in the geologic timescale, a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma (million years ago), approximately. The original type locality is in the vicinity of Apt. The Aptian was introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1840. Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction Event
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the background extinction rate and the rate of speciation. Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from disagreement as to what constitutes a "major" extinction event, and the data chosen to measure past diversity. The "Big Five" mass extinctions In a landmark paper published in 1982, Jack Sepkoski and David M. Raup identified five particular geological intervals with excessive diversity loss. They were originally identified as outliers on a general trend of decreasing extinction rates during the Phanerozoic, but as more stringent statistical tests have been applied ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aptian Extinction
The Aptian extinction was an extinction event of the early Cretaceous Period. It is dated to c. 116 or 117 million years ago, in the middle of the Aptian stage of the geological time scale, and has sometimes been termed the mid-Aptian extinction event as a result. It is classified as a minor extinction event, rather than a major event like the famous Cretaceous–Paleogene extinction event that brought about the end of the "age of dinosaurs" and the Mesozoic Era. The Aptian event is most readily detected among marine rather than terrestrial fossil deposits. Nonetheless, "From a palaeobotanical perspective, the Aptian Extinction Event is an episode of importance, deserving a higher status among other minor events." The Aptian event may have been causally connected with the Rahjamal Traps volcanism episode in the Bengal region of India, associated with the Kerguelen hotspot of volcanic activity. Courtillot, Vincent. ''Evolutionary Catastrophes: The Science of Mass Extinctions.'' Cambr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anoxic Event
Oceanic anoxic events or anoxic events ( anoxia conditions) describe periods wherein large expanses of Earth's oceans were depleted of dissolved oxygen (O2), creating toxic, euxinic (anoxic and sulfidic) waters. Although anoxic events have not happened for millions of years, the geologic record shows that they happened many times in the past. Anoxic events coincided with several mass extinctions and may have contributed to them. These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating. On the other hand, there are widespread, various black-shale beds from the mid-Cretaceous which indicate anoxic events but are not associated with mass extinctions. Many geologists believe oceanic anoxic events are strongly linked to the slowing of ocean circulation, climatic warming, and elevated levels of greenhouse gases. Researchers have proposed enhanced volcanism (the release of CO2) as the "central external trigger for euxinia." British ocea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Western Europe
Western Europe is the western region of Europe. The region's countries and territories vary depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean world, the Roman Empire (Western Roman Empire and Eastern Roman Empire), and medieval "Christendom" (Western Christianity and Eastern Christianity). Beginning with the Renaissance and the Age of Discovery, roughly from the 15th century, the concept of ''Europe'' as "the West" slowly became distinguished from and eventually replaced the dominant use of "Christendom" as the preferred endonym within the region. By the Age of Enlightenment and the Industrial Revolution, the concepts of "Eastern Europe" and "Western Europe" were more regularly used. Historical divisions Classical antiquity and medieval origins Prior to the Roman conquest, a large part of Western Europe had adopted the newly developed La Tène culture. As the Roman domain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 Ma (million years ago). The Albian is preceded by the Aptian and followed by the Cenomanian. Stratigraphic definitions The Albian Stage was first proposed in 1842 by Alcide d'Orbigny. It was named after Alba, the Latin name for River Aube in France. A Global Boundary Stratotype Section and Point (GSSP), ratified by the IUGS in 2016, defines the base of the Albian as the first occurrence of the planktonic foraminiferan '' Microhedbergella renilaevis'' at the Col de Pré-Guittard section, Arnayon, Drôme, France. The top of the Albian Stage (the base of the Cenomanian Stage and Upper Cretaceous Series) is defined as the place where the foram species '' Rotalipora globotruncanoides'' first appears in the stratigraphic column. The Albia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barremian
The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded by the Hauterivian and followed by the Aptian Stage.See Gradstein ''et al.'' (2004) or the online geowhen database (link below) Stratigraphic definitions The original type locality for the Barremian Stage is in the vicinity of the village of Barrême, Alpes-de-Haute-Provence, France. Henri Coquand defined the stage and named it in 1873. The base of the Barremian is determined by the first appearance of the ammonites ''Spitidiscus hugii'' and ''Spitidiscus vandeckii''. The end of the Barremian is determined by the geomagnetic reversal at the start of the M0r chronozone, which is biologically near the first appearance of the ammonite '' Paradeshayesites oglanlensis''. Regional equivalents The Barremian falls in the Gallic epoch, a su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annum
A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars. For the Gregorian calendar, the average length of the calendar year (the mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
