"to a nearly featureless plain, perhaps resembling the vast flat areas in which similar Precambrian rocks are now exposed in central and eastern Canada. At the close of Precambrian time, about 600 million years ago, the plain slowly subsided and the site of the future Teton Range disappeared beneath shallow seas that were to wash across it intermittently for the next 500 million years. Deposition resumed in the Cambrian period and continued through the Paleozoic era, creating nine major formations which together are 4,000 feet (1,200 m) thick (the only geologic period in the Paleozoic not represented is the Silurian)."
"Paleocene The Paleocene () or Palaeocene, the ""old recent"", is a geological epoch that lasted from about . 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 (K–Pg) boundary. This was a time marked by the demise of non-avian dinosaurs, giant marine reptiles"
"Era (geology) A geologic era is a subdivision of geologic time that divides an eon into smaller units of time. The Phanerozoic Eon is divided into three such time frames: the Paleozoic, Mesozoic, and Cenozoic (meaning ""old life"", ""middle life"" and ""recent life"") that represent the major stages in the macroscopic fossil record. These eras are separated by catastrophic extinction boundaries, the P-T boundary between the Paleozoic and the Mesozoic and the K-Pg boundary between the Mesozoic and the Cenozoic. There is evidence that catastrophic meteorite impacts played a role in demarcating the differences between the eras. The Hadean, Archean"
"Paleogene The Paleogene (; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago (Mya) to the beginning of the Neogene Period Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon. The Paleogene is most notable for being the time during which mammals diversified from relatively small, simple forms into a large group of diverse animals in the wake of the Cretaceous–Paleogene extinction event that ended the preceding Cretaceous Period. This period consists"
"Phanerozoic The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers million years to the present, and began with the Cambrian Period when diverse hard-shelled animals first appeared. Its name was derived from the Ancient Greek words () and (), meaning ""visible life"", since it was once believed that life began in the Cambrian, the first period of this eon. The term ""Phanerozoic"" was coined in 1930 by the American geologist George Halcott Chadwick (1876–1953). The time before the Phanerozoic, called the ""Precambrian"","
"vacancy of niches left by the KT event. Large flightless birds have been found in late Paleocene deposits, including the omnivorous ""Gastornis"" in Europe and carnivorous terror birds in South America, the latter of which survived until the Pleistocene. In the late Paleocene, early owl types appeared, such as ""Ogygoptynx"" in the United States and ""Berruornis"" in France. Paleocene The Paleocene () or Palaeocene, the ""old recent"", is a geological epoch that lasted from about . It is the first epoch of the Paleogene Period in the modern Cenozoic Era. As with many geologic periods, the strata that define the"
"of the Mesozoic era, the continents had rifted into nearly their present form. Laurasia became North America and Eurasia, while Gondwana split into South America, Africa, Australia, Antarctica and the Indian subcontinent, which collided with the Asian plate. This impact gave rise to the Himalayas. The Tethys Sea, which had separated the northern continents from Africa and India, began to close up, forming the Mediterranean sea. The Paleogene (alternatively Palaeogene) Period is a unit of geologic time that began and ended 23.03 Ma and comprises the first part of the Cenozoic Era. This period consists of the Paleocene, Eocene and"
"failure of circulation models to simulate paleoclimate data. The Paleocene (the first epoch of the Paleogene) immediately followed the asteroid impact that destroyed the dinosaurs and the Cretaceous world. It marks the transition between the dinosaurs of the Mesozoic and the emergence of the larger mammals of the Eocene (Cenozoic). The early part of the period experienced cooler temperatures and a more arid climate than existed before the asteroid. This is most likely due to atmospheric dust reflecting sunlight for an extended time. But in the latter part of the epoch, the temperatures warmed significantly, resulting in the absence of"
"before a reliable (fossil) record of life; it began with the formation of the planet and ended 4.0 billion years ago. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution. The succeeding eon is the Phanerozoic, divided into three eras: the Palaeozoic, an era of arthropods, fishes, and the first life on land; the Mesozoic, which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs; and the Cenozoic, which saw the rise of mammals. Recognizable humans emerged at most 2 million years ago, a vanishingly small period on the geological"
"Dying"", the third and most severe mass extinction. Geologically, the Paleozoic started shortly after the breakup of the supercontinent Pannotia. Throughout the early Paleozoic, that landmass was broken into a substantial number of continents. Towards the end of the era, the continents gathered together into a supercontinent called Pangaea, which included most of the Earth's land area. The earliest two periods, the Ordovician and Silurian, were warm greenhouse periods, with the highest sea levels of the Paleozoic (200 m above today's); the warm climate was interrupted only by a cool period, the Early Palaeozoic Icehouse, culminating in the Huronian glaciation,"
"Paleoproterozoic Paleoproterozoic Era (;), spanning the time period from (2.5–1.6 Ga), is the first of the three sub-divisions (eras) of the Proterozoic Eon. The Paleoproterozoic is also the longest era of the Earth's geological history. It was during this era that the continents first stabilized. Paleontological evidence suggests that the Earth's rotational rate during this era resulted in 20-hour days ~1.8 billion years ago, implying a total of ~450 days per year. Before the enormous increase in atmospheric oxygen, almost all existing lifeforms were anaerobic, i.e., their metabolism was based upon a form of cellular respiration that did not require"
"and Proterozoic eons were as a whole formerly called the Precambrian. This covered the four billion years of Earth history prior to the appearance of hard-shelled animals. More recently, however, the Archean and Proterozoic eons have been subdivided into eras of their own. Geologic eras are further subdivided into geologic periods, although the Archean eras have yet to be subdivided in this way. Era (geology) A geologic era is a subdivision of geologic time that divides an eon into smaller units of time. The Phanerozoic Eon is divided into three such time frames: the Paleozoic, Mesozoic, and Cenozoic (meaning ""old"
"the Phanerozoic Eon, preceded by the Paleozoic (""ancient life"") and succeeded by the Cenozoic (""new life""). The era is subdivided into three major periods: the Triassic, Jurassic, and Cretaceous, which are further subdivided into a number of epochs and stages. The era began in the wake of the Permian–Triassic extinction event, the largest well-documented mass extinction in Earth's history, and ended with the Cretaceous–Paleogene extinction event, another mass extinction whose victims included the non-avian dinosaurs. The Mesozoic was a time of significant tectonic, climate and evolutionary activity. The era witnessed the gradual rifting of the supercontinent Pangaea into separate landmasses"
"Siderian The Siderian Period (; , meaning ""iron"") is the first geologic period in the Paleoproterozoic Era and lasted from Ma to Ma (million years ago). Instead of being based on stratigraphy, these dates are defined chronometrically. The laying down of the banded iron formations (BIFs) peaked early in this period. BIFs were formed as anaerobic cyanobacteria produced waste oxygen that combined with iron, forming magnetite (FeO, an iron oxide). This process removed iron from the Earth's oceans, presumably turning greenish seas clear. Eventually, with no remaining iron in the oceans to serve as an oxygen sink, the process allowed"
"early Paleozoic. Sediment was derived from continental sources and was deposited in shallow water. These rocks have since been metamorphosed. Heat generated from the Farallon Plate subducting below the North American Plate led to the creation of an island arc of volcanoes on the west coast of proto-North America between the late Devonian and Permian periods. Later volcanism in the Jurassic intruded and covered these rocks in what may have been magmatic activity associated with the early stages of the creation of the Sierra Nevada Batholith. 95% of these rocks were eventually removed by uplifted-accelerated erosion. The first phase of"
"at the first appearance of a group of small, generally disarticulated, armored forms termed 'the small shelly fauna'. The three different dividing points are within a few million years of each other. In the older literature, the term ""Phanerozoic"" is generally used as a label for the time period of interest to paleontologists, but that use of the term seems to be falling into disuse in more modern literature. The Phanerozoic is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic, which are further subdivided into 12 periods. The Paleozoic features the rise of fish, amphibians and reptiles. The Mesozoic"
"approximately 542 million years ago. It consists of three eras: The Paleozoic, Mesozoic, and Cenozoic, and is the time when multi-cellular life greatly diversified into almost all the organisms known today. The Paleozoic (""old life"") era was the first and longest era of the Phanerozoic eon, lasting from 542 to 251 Ma. During the Paleozoic, many modern groups of life came into existence. Life colonized the land, first plants, then animals. Two major extinctions occurred. The continents formed at the break-up of Pannotia and Rodinia at the end of the Proterozoic slowly moved together again, forming the supercontinent Pangaea in"
"Period boundaries are the only Precambrian boundaries defined by biologic Global Boundary Stratotype Section and Points, rather than the absolute Global Standard Stratigraphic Ages. Neoproterozoic The Neoproterozoic Era is the unit of geologic time from . It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran Periods. It is preceded by the Mesoproterozoic era and succeeded by the Paleozoic era. The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets reached the equator and formed a possible ""Snowball Earth"". The earliest fossils"
"Ordovician Period (about 440–480 million years ago), a change in plate motions set the stage for the first Paleozoic mountain building event (Taconic orogeny) in North America. The once quiet, Appalachian passive margin changed to a very active plate boundary when a neighboring oceanic plate, the Iapetus, collided with and began sinking beneath the North American craton. With the birth of this new subduction zone, the early Appalachians were born. Along the continental margin, volcanoes grew, coincident with the initiation of subduction. Thrust faulting uplifted and warped older sedimentary rock laid down on the passive margin. As mountains rose, erosion"
"the late Paleozoic. The Mesozoic (""middle life"") era lasted from 251 Ma to Ma. It is subdivided into the Triassic, Jurassic, and Cretaceous periods. The era began with the Permian–Triassic extinction event, the most severe extinction event in the fossil record; 95% of the species on Earth died out. It ended with the Cretaceous–Paleogene extinction event that wiped out the dinosaurs.. The Cenozoic (""new life"") era began at Ma, and is subdivided into the Paleogene, Neogene, and Quaternary periods. These three periods are further split into seven sub-divisions, with the Paleogene composed of The Paleocene, Eocene, and Oligocene, the Neogene"
"Neoproterozoic The Neoproterozoic Era is the unit of geologic time from . It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran Periods. It is preceded by the Mesoproterozoic era and succeeded by the Paleozoic era. The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets reached the equator and formed a possible ""Snowball Earth"". The earliest fossils of multicellular life are found in the Ediacaran, including the Ediacarans, which were the earliest animals. According to Rino and co-workers, the sum of"
"Mesoproterozoic The Mesoproterozoic Era is a geologic era that occurred from . The Mesoproterozoic was the first period of Earth's history of which a fairly definitive geological record survives. Continents existed during the preceding era (the Paleoproterozoic), but little is known about them. The continental masses of the Mesoproterozoic were more or less the same ones that exist today. The major events of this era are the breakup of the Columbia supercontinent, the formation of the Rodinia supercontinent, and the evolution of sexual reproduction. This era is marked by the further development of continental plates and plate tectonics. The first"
"Since 1969, museum archaeologists have been conducting underwater archaeological excavations beneath the Caspian Sea. The Lower Paleolithic, the first stage of the Paleolithic era, covers the period from 3.2 million years ago to 100,000 years ago. The main belongings to prehistoric humans for this period were found in the Azykh cave in the Guruchay valley near Fuzuli region. It is hard to distinguish the instruments found here from river stones. Bashing, cracking, knapping, pecking, grinding or polishing stones of various kinds to manufacture tools were found in this period. As well as the bones of various wild animals were found"
"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 relatively 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, Eocene and Oligocene. The Paleocene epoch lasted from 66 million to 56 million years"
"eras (from oldest to youngest): the Paleoproterozoic, Mesoproterozoic, and Neoproterozoic. The well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic; several glaciations, which produced the hypothesized Snowball Earth during the Cryogenian Period in the late Neoproterozoic Era; and the Ediacaran Period (635 to 541 Ma) which is characterized by the evolution of abundant soft-bodied multicellular organisms and provides us with the first obvious fossil evidence of life on earth. The geologic record of the Proterozoic Eon is more complete than that for the preceding Archean Eon. In contrast to the deep-water deposits of the"
"Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pЄ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic eon, which is named after Cambria, the Latinised name for Wales, where rocks from this age were first studied. The Precambrian accounts for 88% of the Earth's geologic time. The Precambrian (colored green in the timeline figure) is an informal unit of geologic time, subdivided into three eons (Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation"
"Following the Paleozoic, the Mesozoic extended roughly 186 million years, from when the Cenozoic Era began. This time frame is separated into three geologic periods. From oldest to youngest: The lower boundary of the Mesozoic is set by the Permian–Triassic extinction event, during which approximately 90% to 96% of marine species and 70% of terrestrial vertebrates became extinct. It is also known as the ""Great Dying"" because it is considered the largest mass extinction in the Earth's history. The upper boundary of the Mesozoic is set at the Cretaceous–Paleogene extinction event (or K–Pg extinction event), which may have been caused"
"Paleolithic Europe Paleolithic Europe, the Lower or Old Stone Age in Europe encompasses the era from the arrival of the first archaic humans, about 1.4 million years ago until the beginning of the Mesolithic (also Epipaleolithic) around 10,000 years ago. The period thus covers over 99% of human history on the European continent. The period is usually divided into: The oldest evidence of human occupation in Eastern Europe comes from the Kozarnika cave in Bulgaria where a single human tooth and flint artifacts have been dated to at least 1.4 million years ago. In Western Europe at Atapuerca in Spain,"
"Paleolithic The Paleolithic or Palaeolithic () is a period in human prehistory distinguished by the original development of stone tools that covers c. 99% of human technological prehistory. It extends from the earliest known use of stone tools by hominins c. 3.3 million years ago, to the end of the Pleistocene c. 11,650 cal BP. The Paleolithic is followed in Europe by the Mesolithic, although the date of the transition varies geographically by several thousand years. During the Paleolithic, hominins grouped together in small societies such as bands, and subsisted by gathering plants and fishing, hunting or scavenging wild animals."
"the middle Ordovician Period (about 496–440 Ma), a change in plate motions set the stage for the first Paleozoic mountain-building event (Taconic orogeny) in North America. The once-quiet Appalachian passive margin changed to a very active plate boundary when a neighboring oceanic plate, the Iapetus, collided with and began sinking beneath the North American craton. With the birth of this new subduction zone, the early Appalachians were born. Along the continental margin, volcanoes grew, coincident with the initiation of subduction. Thrust faulting uplifted and warped older sedimentary rock laid down on the passive margin. As the mountains rose, erosion began"
"the buildup of an oxygen-rich atmosphere. This second, follow-on event is known as the oxygen catastrophe, which, some geologists believe triggered the Huronian glaciation. Since the time period from 2420 Ma to 2250 Ma is well-defined by the lower edge of iron-deposition layers, an alternative period named the Oxygenian, based on stratigraphy instead of chronometry, was suggested in 2012 by Gradstein ""et al."" in a geological timescale review but, , this has not yet been officially adopted by the IUGS. Siderian The Siderian Period (; , meaning ""iron"") is the first geologic period in the Paleoproterozoic Era and lasted from"
"may be found at elevations of several hundred meters. Pleistocene The Pleistocene (, often colloquially referred to as the Ice Age) is the geological epoch which lasted from about 2,588,000 to 11,700 years ago, spanning the world's most recent period of repeated glaciations. 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 Pleistocene is the first epoch of the Quaternary Period or sixth epoch of the Cenozoic Era. In the ICS timescale, the Pleistocene is divided into four stages or ages, the"
"Late Paleozoic (290 to 250 mya), those materials began to fracture. Masses of magma began rising to the surface, and in this way the granites were formed. The final phase of this era produced a general elevation of the Peñalara massif. From the end of the Paleozoic and during the Mesozoic (250 to 66 mya), the processes of erosion began to wear down the contours of the land. In this last period occurred a monumental departure from the ocean, which left subaquatic zones exposed on the surface (prior to this, it is likely that the sierra was not more than"