The Cenozoic Era meaning "new life", is the current and most recent of the three Phanerozoic geological eras, following the Mesozoic Era and extending from 66 million years ago to the present day. The Cenozoic is known as the Age of Mammals, because the extinction of many groups allowed mammals to diversify so that large mammals dominated it; the continents moved into their current positions during this era. Early in the Cenozoic, following the K-Pg extinction event, most of the fauna was small, included small mammals, birds and amphibians. From a geological perspective, it did not take long for mammals and birds to diversify in the absence of the large reptiles that had dominated during the Mesozoic. A group of avians known as the "terror birds" grew larger than the average human and were formidable predators. Mammals came to occupy every available niche, some grew large, attaining sizes not seen in most of today's mammals; the Earth's climate had begun a drying and cooling trend, culminating in the glaciations of the Pleistocene Epoch, offset by the Paleocene-Eocene Thermal Maximum.
Cenozoic, meaning "new life," is derived from Greek καινός kainós "new," and ζωή zōḗ "life." The era is known as the Cænozoic, Caenozoic, or Cainozoic. The name "Cenozoic" was proposed in 1840 by the British geologist John Phillips; the Cenozoic is divided into three periods: the Paleogene and Quaternary. The Quaternary Period was recognized by the International Commission on Stratigraphy in June 2009, the former term, Tertiary Period, became disused in 2004 due to the need to divide the Cenozoic into periods more like those of the earlier Paleozoic and Mesozoic eras; the common use of epochs during the Cenozoic helps paleontologists better organize and group the many significant events that occurred during this comparatively short interval of time. Knowledge of this era is more detailed than any other era because of the young, well-preserved rocks associated with it; the Paleogene spans from the extinction of non-avian dinosaurs, 66 million years ago, to the dawn of the Neogene, 23.03 million years ago.
It features three epochs: the Paleocene and Oligocene. The Paleocene epoch lasted from 66 million to 56 million years ago. Modern placental mammals originated during this time; the Paleocene is a transitional point between the devastation, the K-T extinction, to the rich jungle environment, the Early Eocene. The Early Paleocene saw the recovery of the earth; the continents began to take their modern shape, but all the continents and the subcontinent of India were separated from each other. Afro-Eurasia was separated by the Tethys Sea, the Americas were separated by the strait of Panama, as the isthmus had not yet formed; this epoch featured a general warming trend, with jungles reaching the poles. The oceans were dominated by sharks. Archaic mammals filled the world such as creodonts; the Eocene Epoch ranged from 56 million years to 33.9 million years ago. In the Early-Eocene, species living in dense forest were unable to evolve into larger forms, as in the Paleocene. There was nothing over the weight of 10 kilograms.
Among them were early primates and horses along with many other early forms of mammals. At the top of the food chains were huge birds, such as Paracrax; the temperature was 30 degrees Celsius with little temperature gradient from pole to pole. In the Mid-Eocene, the Circumpolar-Antarctic current between Australia and Antarctica formed; this disrupted ocean currents worldwide and as a result caused a global cooling effect, shrinking the jungles. This allowed mammals to grow to mammoth proportions, such as whales which, by that time, had become fully aquatic. Mammals like Andrewsarchus were at the top of the food-chain; the Late Eocene saw the rebirth of seasons, which caused the expansion of savanna-like areas, along with the evolution of grass. The end of the Eocene was marked by the Eocene-Oligocene extinction event, the European face of, known as the Grande Coupure; the Oligocene Epoch spans from 33.9 million to 23.03 million years ago. The Oligocene featured the expansion of grass which had led to many new species to evolve, including the first elephants, dogs and many other species still prevalent today.
Many other species of plants evolved in this period too. A cooling period featuring seasonal rains was still in effect. Mammals still continued to grow larger; the Neogene spans from 23.03 million to 2.58 million years ago. It features 2 epochs: the Miocene, the Pliocene; the Miocene epoch spans from 23.03 to 5.333 million years ago and is a period in which grass spread further, dominating a large portion of the world, at the expense of forests. Kelp forests evolved, encouraging the evolution such as sea otters. During this time, perissodactyla thrived, evolved into many different varieties. Apes evolved into 30 species; the Tethys Sea closed with the creation of the Arabian Peninsula, leaving only remnants as the Black, Red and Caspian Seas. This increased aridity. Many new plants evolved: 95% of modern seed plants evolved in the mid-Miocene; the Pliocene epoch lasted from 5.333 to 2.58 million years ago. The Pliocene featured dramatic climactic changes, which led to modern species and plants; the Mediterranean Sea dried up for several million years (because the ice ages reduced sea levels, disconnecting the Atlantic from
Millstone Grit is the name given to any of a number of coarse-grained sandstones of Carboniferous age which occur in the British Isles. The name derives from its use in earlier times as a source of millstones for use principally in watermills. Geologists refer to the whole suite of rocks that encompass the individual limestone beds and the intervening mudstones as the Millstone Grit Group; the term Millstone Grit Series was used to refer to the rocks now included within the Millstone Grit Group together with the underlying Edale Shale Group. The term gritstone describes any sandstone composed of coarse angular grains, refers to such sandstones within the Peak District and neighbouring areas of Northern England. Rocks assigned to the Millstone Grit Group occur over a wide area of Northern England, where they are a hugely important landscape-forming element of the rock succession, they occur in parts of northeast Wales and northwest Ireland. The group comprises a succession of sandstones and siltstones, the specifics of the sequence varying from one area to another.
They give rise both to a number of escarpments, known locally as edges, a series of high plateaux throughout the region, many of which are of considerable cultural significance. They are the major landscape-forming rocks of the northern part of the Peak District and of its eastern and western flanks in the counties of Derbyshire and Cheshire; the great expanses of moorland around Bleaklow and Black Hill and fringed with broken outcrops of gritstone are characteristic of the area. The ‘eastern edges’ of the Peak District’ comprise a broadly north-south arranged series of west-facing cliffs from Bamford Edge in the north through Stanage Edge, Burbage Edge, Froggatt Edge, Curbar Edge, Baslow Edge, Gardom's Edge, Birchen Edge, Dobb/Chatsworth Edge, Harland Edge and Fallinge Edge in the south. To the east of these edges is a broad band of flat moorland known as the Eastern Moors. Towards the western margins of the Peak District are a rather more broken series of edges, facing in a variety of directions, from those surrounding the high plateaux of Kinder Scout and Combs Moss to the imposing crags of the Roaches, Hen Cloud and Ramshaw Rocks in the south.
A millstone shaped from Millstone Grit quarried in the area has been adopted as the emblem of the Peak District National Park. As an image, the millstone is visible on literature but use is made of the objects themselves at many of the entrances to the National Park; these rocks extend northwards through the South Pennines of Lancashire and West Yorkshire and westwards into the Forest of Rossendale and West Pennines and the Forest of Bowland in Lancashire. At the Yorkshire Dales they cover the south-east edge, but north of the Craven Faults, due to weathering, they form only cappings to separate hills. A small area of Millstone Grit Group rocks stretches through Flintshire and Wrexham into the northwest corner of Shropshire near Oswestry; the term'Millstone Grit' was adopted in South Wales where rocks of similar age and lithology are found though the Millstone Grit series of this region has been formally renamed by the British Geological Survey as the Marros Group. The thickest bed of sandstone within it was known as the Basal Grit.
This has now been renamed as the Twrch Sandstone. The Farewell Rock was considered to be the uppermost unit of the Millstone Grit series of South Wales though it is now included within the overlying South Wales Coal Measures. Main article: Marros Group The term has been adopted at Slieve Anierin in northwest Ireland, describing the series of shales and coal seams, occurring from the base of the Namurian upwards; the Millstone Grit dates from the Namurian Stage of the Carboniferous Period. At this time a series of isolated uplands existed across the British Isles region. One particular east-west aligned landmass stretched from Wales through the English Midlands and East Anglia to the continent and is now known as the Wales-Brabant High though was referred to as St George’s Land. Other uplands the erosion of which would provide the source material for the Millstone Grit lay to the north and northeast of the region; the Pennine Basin received input of sand and mud from southerly directed rivers from these northern landmasses.
Rivers running north off the Wales-Brabant High deposited material in the southern parts of the Pennine basin from northeast Wales to the Peak District. Southerly flowing rivers from this same landmass were responsible for the Millstone Grit/Marros Group succession in South Wales. During much of the Carboniferous Period, world sea-levels were fluctuating in response to the growth and decline of a series of major ice-caps over the continents clustered around the South Pole. Britain lay in the equatorial region. At times of high sea-level and mud accumulated within the Pennine basin whilst at times of low sea-level, major deltas prograded across the region, their legacy being the thick sandstone beds of the Millstone Grit Group; the Millstone Grit Group comprises over thirty individually named sandstones, some of regional extent, others more local in their occurrence. The intervening mudstones and siltstones are not named though important marine bands within them are named; the oldest, hence lowermost in the succession is the thick Pendle Grit of central Lancashire.
It is succeeded by the sandstone known variously as the Brennand Grit, Warley Wise Grit and Grassington Grit. These are all of Pendleian age – the lowermost sub-stage of the Namurian; the Lower Follifoot Grit, Silver Hills Sandstone, Nottage Crag Grit, Marchup Grit, Red Scar Grit, Ward’s Stone Sandstone, Cocklett Scar Sandstones and Dure Clough Sandstones are all assigned to the follow
The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago, to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, where rocks from this period were first studied; the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods became well-established. Fish reached substantial diversity during this time, leading the Devonian to be dubbed the "Age of Fishes." The first ray-finned and lobe-finned bony fish appeared, while the placoderms began dominating every known aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral and pelvic fins evolved into legs.
In the oceans, primitive sharks became more numerous than in the Late Ordovician. The first ammonites, species of molluscs, appeared. Trilobites, the mollusc-like brachiopods and the great coral reefs, were still common; the Late Devonian extinction which started about 375 million years ago affected marine life, killing off all placodermi, all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, the early formation of the small continent of Euramerica in between; the period is named after Devon, a county in southwestern England, where a controversial argument in the 1830s over the age and structure of the rocks found distributed throughout the county was resolved by the definition of the Devonian period in the geological timescale. The Great Devonian Controversy was a long period of vigorous argument and counter-argument between the main protagonists of Roderick Murchison with Adam Sedgwick against Henry De la Beche supported by George Bellas Greenough.
Murchison and Sedgwick named the period they proposed as the Devonian System. While the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, to the beginning of the Carboniferous 358.9 Mya. In nineteenth-century texts the Devonian has been called the "Old Red Age", after the red and brown terrestrial deposits known in the United Kingdom as the Old Red Sandstone in which early fossil discoveries were found. Another common term is "Age of the Fishes", referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian and Farlovian stages, the latter three of which are placed in the Devonian; the Devonian has erroneously been characterised as a "greenhouse age", due to sampling bias: most of the early Devonian-age discoveries came from the strata of western Europe and eastern North America, which at the time straddled the Equator as part of the supercontinent of Euramerica where fossil signatures of widespread reefs indicate tropical climates that were warm and moderately humid but in fact the climate in the Devonian differed during its epochs and between geographic regions.
For example, during the Early Devonian, arid conditions were prevalent through much of the world including Siberia, North America, China, but Africa and South America had a warm temperate climate. In the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common; the Devonian Period is formally broken into Early and Late subdivisions. The rocks corresponding to those epochs are referred to as belonging to the Lower and Upper parts of the Devonian System. Early DevonianThe Early Devonian lasted from 419.2 ± 2.8 to 393.3 ± 2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ± 2.8 to 407.6 ± 2.5, was followed by the Emsian, which lasted until the Middle Devonian began, 393.3± 2.7 million years ago. During this time, the first ammonoids appeared. Ammonoids during this time period differed little from their nautiloid counterparts; these ammonoids belong to the order Agoniatitida, which in epochs evolved to new ammonoid orders, for example Goniatitida and Clymeniida.
This class of cephalopod molluscs would dominate the marine fauna until the beginning of the Mesozoic era. Middle DevonianThe Middle Devonian comprised two subdivisions: first the Eifelian, which gave way to the Givetian 387.7± 2.7 million years ago. During this time the jawless agnathan fishes began to decline in diversity in freshwater and marine environments due to drastic environmental changes and due to the increasing competition and diversity of jawed fishes; the shallow, oxygen-depleted waters of Devonian inland lakes, surrounded by primitive plants, provided the environment necessary for certain early fish to develop such essential characteristics as well developed lungs, the ability to crawl out of the water and onto the land for short periods of time. Late DevonianFinally, the Late Devonian started with the Frasnian, 382.7 ± 2.8 to 372.2 ± 2.5, during which the first forests took shape on land. The first tetrapods appeared in the fossil record in the ensuing Famennian subdivisi
The Paleocene or Palaeocene, the "old recent", is a geological epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Paleogene Period in the modern Cenozoic Era; as with many geologic periods, the strata that define the epoch's beginning and end are well identified, but the exact ages remain uncertain. The Paleocene Epoch is bracketed by two major events in Earth's history, it started with the mass extinction event at the end of the Cretaceous, known as the Cretaceous–Paleogene boundary. This was a time marked by the demise of non-avian dinosaurs, giant marine reptiles and much other fauna and flora; the die-off of the dinosaurs left unfilled ecological niches worldwide. The Paleocene ended with the Paleocene–Eocene Thermal Maximum, a geologically brief interval characterized by extreme changes in climate and carbon cycling; the name "Paleocene" comes from Ancient Greek and refers to the "old" "new" fauna that arose during the epoch. The K–Pg boundary that marks the separation between Cretaceous and Paleocene is visible in the geological record of much of the Earth by a discontinuity in the fossil fauna and high iridium levels.
There is fossil evidence of abrupt changes in flora and fauna. There is some evidence that a substantial but short-lived climatic change may have happened in the early decades of the Paleocene. There are several theories about the cause of the K–Pg extinction event, with most evidence supporting the impact of a 10 km diameter asteroid forming the buried Chicxulub crater on the coast of Yucatan, Mexico; the end of the Paleocene was marked by a time of major change, one of the most significant periods of global change during the Cenozoic. The Paleocene–Eocene Thermal Maximum upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and a major turnover in mammals on land; the Paleocene is divided into three stages, the Danian, the Selandian and the Thanetian, as shown in the table above. Additionally, the Paleocene is divided into six Mammal Paleogene zones; the early Paleocene was cooler and drier than the preceding Cretaceous, though temperatures rose during the Paleocene–Eocene Thermal Maximum.
The climate became warm and humid worldwide towards the Eocene boundary, with subtropical vegetation growing in Greenland and Patagonia, crocodilians swimming off the coast of Greenland, early primates evolving in the tropical palm forests of northern Wyoming. The Earth's poles were temperate. In many ways, the Paleocene continued processes. During the Paleocene, the continents continued to drift toward their present positions. Supercontinent Laurasia had not yet separated into three continents - Europe and Greenland were still connected, North America and Asia were still intermittently joined by a land bridge, while Greenland and North America were beginning to separate; the Laramide orogeny of the late Cretaceous continued to uplift the Rocky Mountains in the American west, which ended in the succeeding epoch. South and North America remained separated by equatorial seas. Africa was heading north towards Europe closing the Tethys Ocean, India began its migration to Asia that would lead to a tectonic collision and the formation of the Himalayas.
The inland seas in North America and Europe had receded by the beginning of the Paleocene, making way for new land-based flora and fauna. Warm seas circulated including the poles; the earliest Paleocene featured a low diversity and abundance of marine life, but this trend reversed in the epoch. Tropical conditions gave rise including coral reefs. With the demise of marine reptiles at the end of the Cretaceous, sharks became the top predators. At the end of the Cretaceous, the ammonites and many species of foraminifera became extinct. Marine fauna came to resemble modern fauna, with only the marine mammals and the Carcharhinid sharks missing. Terrestrial Paleocene strata overlying the K–Pg boundary is in places marked by a "fern spike": a bed rich in fern fossils. Ferns are the first species to colonize areas damaged by forest fires. In general, the Paleocene is marked by the development of modern plant species. Cacti and palm trees appeared. Paleocene and plant fossils are attributed to modern genera or to related taxa.
The warm temperatures worldwide gave rise to thick tropical, sub-tropical and deciduous forest cover around the globe with ice-free polar regions covered with coniferous and deciduous trees. With no large browsing dinosaurs to thin them, Paleocene forests were denser than those of the Cretaceous. Flowering plants, first seen in the Cretaceous, continued to develop and proliferate, along with them coevolved the insects that fed on these plants and pollinated them. Mammals had first appeared in the Late Triassic, evolving from advanced cynodonts, developed alongside the dinosaurs, exploiting ecological niches untouched by the larger and more famous Mesozoic animals: in the insect-rich fo
The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago. The Miocene was named by Charles Lyell; the Miocene is followed by the Pliocene. As the earth went from the Oligocene through the Miocene and into the Pliocene, the climate cooled towards a series of ice ages; the Miocene boundaries are not marked by a single distinct global event but consist rather of regionally defined boundaries between the warmer Oligocene and the cooler Pliocene Epoch. The Apes first evolved and diversified during the early Miocene, becoming widespread in the Old World. By the end of this epoch and the start of the following one, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path during the final Messinian stage of the Miocene; as in the Oligocene before it, grasslands continued to forests to dwindle in extent. In the seas of the Miocene, kelp forests made their first appearance and soon became one of Earth's most productive ecosystems.
The plants and animals of the Miocene were recognizably modern. Mammals and birds were well-established. Whales and kelp spread; the Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the geology of the Himalaya occurred during the Miocene, affecting monsoonal patterns in Asia, which were interlinked with glacial periods in the northern hemisphere. The Miocene faunal stages from youngest to oldest are named according to the International Commission on Stratigraphy: Regionally, other systems are used, based on characteristic land mammals. Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean, causing both the rise of the Andes and a southward extension of the Meso-American peninsula. Mountain building took place in western North America and East Asia. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines.
Well studied continental exposures occur in Argentina. India continued creating dramatic new mountain ranges; the Tethys Seaway continued to shrink and disappeared as Africa collided with Eurasia in the Turkish–Arabian region between 19 and 12 Ma. The subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea near the end of the Miocene; the global trend was towards increasing aridity caused by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the late Miocene was responsible for the shrinking of tropical rain forests in that region, Australia got drier as it entered a zone of low rainfall in the Late Miocene. During the Oligocene and Early Miocene the coast of northern Brazil, south-central Peru, central Chile and large swathes of inland Patagonia were subject to a marine transgression; the transgressions in the west coast of South America is thought to be caused by a regional phenomenon while the rising central segment of the Andes represents an exception.
While there are numerous registers of Oligo-Miocene transgressions around the world it is doubtful that these correlate. It is thought that the Oligo-Miocene transgression in Patagonia could have temporarily linked the Pacific and Atlantic Oceans, as inferred from the findings of marine invertebrate fossils of both Atlantic and Pacific affinity in La Cascada Formation. Connection would have occurred through narrow epicontinental seaways that formed channels in a dissected topography; the Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene, forming the Chile Triple Junction. At first the Antarctic Plate subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan; as the southern part of Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate begun to subduct beneath Patagonia so that the Chile Triple Junction advanced to the north over time.
The asthenospheric window associated to the triple junction disturbed previous patterns of mantle convection beneath Patagonia inducing an uplift of ca. 1 km that reversed the Oligocene–Miocene transgression. Climates remained moderately warm, although the slow global cooling that led to the Pleistocene glaciations continued. Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivalled that of the Oligocene; the Miocene warming b
Quaternary 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. It follows the Neogene Period and spans from 2.588 ± 0.005 million years ago to the present. The Quaternary Period is divided into two epochs: the Holocene; the informal term "Late Quaternary" refers to the past 0.5–1.0 million years. The Quaternary Period is defined by the cyclic growth and decay of continental ice sheets associated with Milankovitch cycles and the associated climate and environmental changes that occurred. In 1759 Giovanni Arduino proposed that the geological strata of northern Italy could be divided into four successive formations or "orders"; the term "quaternary" was introduced by Jules Desnoyers in 1829 for sediments of France's Seine Basin that seemed to be younger than Tertiary Period rocks. The Quaternary Period extends to the present; the Quaternary covers the time span of glaciations classified as the Pleistocene, includes the present interglacial time-period, the Holocene.
This places the start of the Quaternary at the onset of Northern Hemisphere glaciation 2.6 million years ago. 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 worked with regional subdivisions. From the 1970s, the International Commission on Stratigraphy 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 Mya, long after the start of the major glaciations of the northern hemisphere. The ICS proposed to abolish use of the name Quaternary altogether, which appeared unacceptable to the International Union for Quaternary Research. 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, considered part of the Neogene Period and Pliocene Epoch.
The Anthropocene has been 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 is not designated by the ICS, but a working group has been working on a proposal for the creation of an epoch or sub-period; the 2.6 million years of the Quaternary represents the time during which recognizable humans existed. Over this geologically short time period, there has been 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 the Strait of Bosphorus and Skagerrak during glacial epochs, which turned the Black Sea and Baltic Sea into fresh water, followed by their flooding by rising sea level; 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.
The climate was one of periodic glaciations with continental glaciers moving as far from the poles as 40 degrees latitude. There was a major extinction of large mammals in Northern areas at the end of the Pleistocene Epoch. Many forms such as saber-toothed cats, mastodons, etc. became extinct worldwide. Others, including horses and American cheetahs became extinct in North America. Glaciation took place 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 the Alps; this idea was disputed by another Swiss scientist, Louis Agassiz, but when he undertook to disprove it, he ended up affirming his colleague's hypothesis. A year Agassiz raised the hypothesis of a great glacial period that would have had long-reaching general effects.
This idea led to the establishment of the Glacial Theory. In time, thanks to 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 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, all of Antarctica; the Great Lakes formed and giant mammals thrived in parts of North America and Eurasia not covered in ice. These mammals became extinct. Modern humans evolved about 315,000 years ago. During the Quaternary Period, flowering plants, insects dominated
Germany the Federal Republic of Germany, is a country in Central and Western Europe, lying between the Baltic and North Seas to the north, the Alps to the south. It borders Denmark to the north and the Czech Republic to the east and Switzerland to the south, France to the southwest, Luxembourg and the Netherlands to the west. Germany includes 16 constituent states, covers an area of 357,386 square kilometres, has a temperate seasonal climate. With 83 million inhabitants, it is the second most populous state of Europe after Russia, the most populous state lying in Europe, as well as the most populous member state of the European Union. Germany is a decentralized country, its capital and largest metropolis is Berlin, while Frankfurt serves as its financial capital and has the country's busiest airport. Germany's largest urban area is the Ruhr, with its main centres of Essen; the country's other major cities are Hamburg, Cologne, Stuttgart, Düsseldorf, Dresden, Bremen and Nuremberg. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity.
A region named Germania was documented before 100 AD. During the Migration Period, the Germanic tribes expanded southward. Beginning in the 10th century, German territories formed a central part of the Holy Roman Empire. During the 16th century, northern German regions became the centre of the Protestant Reformation. After the collapse of the Holy Roman Empire, the German Confederation was formed in 1815; the German revolutions of 1848–49 resulted in the Frankfurt Parliament establishing major democratic rights. In 1871, Germany became a nation state when most of the German states unified into the Prussian-dominated German Empire. After World War I and the revolution of 1918–19, the Empire was replaced by the parliamentary Weimar Republic; the Nazi seizure of power in 1933 led to the establishment of a dictatorship, the annexation of Austria, World War II, the Holocaust. After the end of World War II in Europe and a period of Allied occupation, Austria was re-established as an independent country and two new German states were founded: West Germany, formed from the American and French occupation zones, East Germany, formed from the Soviet occupation zone.
Following the Revolutions of 1989 that ended communist rule in Central and Eastern Europe, the country was reunified on 3 October 1990. Today, the sovereign state of Germany is a federal parliamentary republic led by a chancellor, it is a great power with a strong economy. As a global leader in several industrial and technological sectors, it is both the world's third-largest exporter and importer of goods; as a developed country with a high standard of living, it upholds a social security and universal health care system, environmental protection, a tuition-free university education. The Federal Republic of Germany was a founding member of the European Economic Community in 1957 and the European Union in 1993, it is part of the Schengen Area and became a co-founder of the Eurozone in 1999. Germany is a member of the United Nations, NATO, the G7, the G20, the OECD. Known for its rich cultural history, Germany has been continuously the home of influential and successful artists, musicians, film people, entrepreneurs, scientists and inventors.
Germany has a large number of World Heritage sites and is among the top tourism destinations in the world. The English word Germany derives from the Latin Germania, which came into use after Julius Caesar adopted it for the peoples east of the Rhine; the German term Deutschland diutisciu land is derived from deutsch, descended from Old High German diutisc "popular" used to distinguish the language of the common people from Latin and its Romance descendants. This in turn descends from Proto-Germanic *þiudiskaz "popular", derived from *þeudō, descended from Proto-Indo-European *tewtéh₂- "people", from which the word Teutons originates; the discovery of the Mauer 1 mandible shows that ancient humans were present in Germany at least 600,000 years ago. The oldest complete hunting weapons found anywhere in the world were discovered in a coal mine in Schöningen between 1994 and 1998 where eight 380,000-year-old wooden javelins of 1.82 to 2.25 m length were unearthed. The Neander Valley was the location where the first non-modern human fossil was discovered.
The Neanderthal 1 fossils are known to be 40,000 years old. Evidence of modern humans dated, has been found in caves in the Swabian Jura near Ulm; the finds included 42,000-year-old bird bone and mammoth ivory flutes which are the oldest musical instruments found, the 40,000-year-old Ice Age Lion Man, the oldest uncontested figurative art discovered, the 35,000-year-old Venus of Hohle Fels, the oldest uncontested human figurative art discovered. The Nebra sky disk is a bronze artefact created during the European Bronze Age attributed to a site near Nebra, Saxony-Anhalt, it is part of UNESCO's Memory of the World Programme. The Germanic tribes are thought to date from the Pre-Roman Iron Age. From southern Scandinavia and north Germany, they expanded south and west from the 1st century BC, coming into contact with the Celtic tribes of Gaul as well