05-17-2023-2341 - Circle with Towers

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Circle with Towers
The sculpture installed in Madison Square Park in 2005

Wikimedia | © OpenStreetMap
Artist	Sol LeWitt
Location	Austin, Texas, United States
	30.2863°N 97.7369°WCoordinates: 30.2863°N 97.7369°W

Circle with Towers is a concrete block 2005/2012 sculpture by American artist Sol LeWitt, installed outside the Bill and Melinda Gates Computer Science Complex on the University of Texas at Austin campus in Austin, Texas, United States.^[1][2] Previously, the artwork was installed in Madison Square Park; the university's public art program, Landmarks, purchased the sculpture from the Madison Square Park Conservancy.^[3]

References

1. 
   

"Circle with Towers". Landmarks. 27 February 2013. Retrieved September 3, 2018.

van Ryzin, Jeanne Claire (February 22, 2013). "UT makes big leap in public art". Austin American-Statesman. Retrieved September 3, 2018.

3. "Sol Lewitt's Circle with Towers Acquired by the University of Texas at Austin". ArtDaily.org. Archived from the original on September 3, 2018. Retrieved September 3, 2018.

External links

• Texas portal
• Visual arts portal

• "Circle with Towers". Public Art Archive.

v t e Public art in Austin, Texas

Works

Circle with Towers Clock Knot The Family Group Larry Monroe Forever Bridge Littlefield Fountain Monochrome for Austin The Seven Mustangs Square Tilt Statue of Albert Sidney Johnston Texas State Cemetery University of Texas at Austin Statue of Barbara Jordan Austin–Bergstrom International Airport University of Texas at Austin Statue of Cesar Chavez Statue of George Washington Statue of Jefferson Davis Statue of Jim Hogg Statue of John Henninger Reagan Statue of Martin Luther King Jr. Statue of Robert E. Lee Statue of Woodrow Wilson Stevie Ray Vaughan Memorial The Torchbearers Willie Nelson statue Texas State Capitol The Battle of San Jacinto Confederate Soldiers Monument Dawn at the Alamo Disabled American Veterans of Texas Monument Goddess of Liberty Heroes of the Alamo Monument Hood's Texas Brigade Monument Korean War Veterans Memorial Pearl Harbor Monument Statue of Sam Houston Statue of Stephen F. Austin Strengthen the Arm of Liberty Monument Surrender of Santa Anna Tejano Monument Ten Commandments Monument Terry's Texas Rangers Monument Texas African American History Memorial Texas Capitol Vietnam Veterans Monument Texas Cowboy Monument Texas Peace Officers' Memorial Texas Pioneer Woman Monument Texas World War II Memorial The Hiker Tribute to Texas Children Monument Veterans of the 36th Infantry, Texas National Guard Monument Volunteer Firemen Monument World War I Monument

This article about a sculpture in Texas is a stub. You can help Wikipedia by expanding it.

Categories:

• Concrete sculptures in the United States
• Outdoor sculptures in Austin, Texas
• University of Texas at Austin campus
• Texas sculpture stubs

https://en.wikipedia.org/wiki/Circle_with_Towers

^{https://en.wikipedia.org/wiki/Laurentia}

^{https://en.wikipedia.org/wiki/Svecofennian_orogeny}

^{https://en.wikipedia.org/wiki/Amazonian_Craton}

^{https://en.wikipedia.org/wiki/Beringia}

^{https://en.wikipedia.org/wiki/Alaska}

^{https://en.wikipedia.org/wiki/Atlantis}

^{https://en.wikipedia.org/wiki/Amasia_(continent)}

^{https://en.wikipedia.org/wiki/Columbia_(supercontinent)}

^{https://en.wikipedia.org/wiki/Pangaea}

^{https://en.wikipedia.org/wiki/Gondwana}

^{https://en.wikipedia.org/wiki/Vaalbara}

^{https://en.wikipedia.org/wiki/Ur_(continent)}

^{https://en.wikipedia.org/wiki/Rodinia}

^{https://en.wikipedia.org/wiki/Zealandia}

^{https://en.wikipedia.org/wiki/Seychelles_Microcontinent}

^{https://en.wikipedia.org/wiki/Aurica_(supercontinent)}

^{https://en.wikipedia.org/wiki/Novopangaea}

^{https://en.wikipedia.org/wiki/Southern_Cone}

^{https://en.wikipedia.org/wiki/Arabian_Peninsula}

^{https://en.wikipedia.org/wiki/Terra_Australis}

^{https://en.wikipedia.org/wiki/Mu_(mythical_lost_continent)}

^{https://en.wikipedia.org/wiki/Hyperborea}

^{https://en.wikipedia.org/wiki/Sahul}

^{https://en.wikipedia.org/wiki/Kazakhstania}

^{https://en.wikipedia.org/wiki/East_Antarctic_Shield}

^{https://en.wikipedia.org/wiki/Amazonian_Craton}

^{https://en.wikipedia.org/wiki/Arctica}

^{https://en.wikipedia.org/wiki/Arctica}

^{https://en.wikipedia.org/wiki/Avalonia}

^{https://en.wikipedia.org/wiki/Atlantica}

^{https://en.wikipedia.org/wiki/Siberia_(continent)}

^{https://en.wikipedia.org/wiki/Eurasia}

^{https://en.wikipedia.org/wiki/Oceania}

^{https://en.wikipedia.org/wiki/Old_World}

^{https://en.wikipedia.org/wiki/New_World}

^{https://en.wikipedia.org/wiki/Nena_(supercontinent)} 

^{https://en.wikipedia.org/wiki/Statherian}

^{https://en.wikipedia.org/wiki/Neoarchean}

^{https://en.wikipedia.org/wiki/Hadean}

^{https://en.wikipedia.org/wiki/Permian}

^{https://en.wikipedia.org/wiki/Eoarchean}

^{https://en.wikipedia.org/wiki/Statherian}

^{https://en.wikipedia.org/wiki/Paleoproterozoic}

^{https://en.wikipedia.org/wiki/Paleogene}

^{https://en.wikipedia.org/wiki/Neogene}

^{https://en.wikipedia.org/wiki/Ediacaran}

^{https://en.wikipedia.org/wiki/Cryogenian}

^{https://en.wikipedia.org/wiki/Tonian}

^{https://en.wikipedia.org/wiki/Stenian}

The Hadean (IPA: /heɪˈdiːən, ˈheɪdiən/ hay-DEE-ən, HAY-dee-ən)^[discuss] is a geologic eon of Earth history preceding the Archean. On Earth, the Hadean coincides with the planet's formation about 4.54 billion years ago^[2][3] The start of the Hadean is now defined as (4567.30 ± 0.16) Ma^[1] set by the age of the oldest solid material in the Solar System, found in some meteorites, about 4.567 billion years old.^[4] The Hadean ended, as defined by the International Commission on Stratigraphy (ICS), 4 billion years ago.^[5]

Hadean rocks are very rare, largely consisting of zircons from one locality in Western Australia.^[6] Hadean geophysical models remain controversial among geologists: it appears that plate tectonics and the growth of continents may have started in the Hadean.^[6] Earth in the early Hadean had a very thick carbon dioxide atmosphere, but eventually oceans of liquid water formed. 

Backscatter electron micrograph of detrital zircons from the Hadean (4.404 ± 0.008 Ga) metasediments of the Jack Hills, Narryer Gneiss Terrane, Western Australia

 

https://en.wikipedia.org/wiki/Hadean

Atmospheric escape is the loss of planetary atmospheric gases to outer space. A number of different mechanisms can be responsible for atmospheric escape; these processes can be divided into thermal escape, non-thermal (or suprathermal) escape, and impact erosion. The relative importance of each loss process depends on the planet's escape velocity, its atmosphere composition, and its distance from its star. Escape occurs when molecular kinetic energy overcomes gravitational energy; in other words, a molecule can escape when it is moving faster than the escape velocity of its planet. Categorizing the rate of atmospheric escape in exoplanets is necessary to determining whether an atmosphere persists, and so the exoplanet's habitability and likelihood of life. 

https://en.wikipedia.org/wiki/Atmospheric_escape 

https://en.wikipedia.org/wiki/Captive

https://en.wikipedia.org/wiki/Magical_thinking

https://en.wikipedia.org/wiki/Displacement

https://en.wikipedia.org/wiki/Wish

A fairy offering wishes, illustration by John Bauer to Alfred Smedberg's The seven wishes

https://en.wikipedia.org/wiki/Wish

The Quaternary (/kwəˈtɜːrnəri, ˈkwɒtərnɛri/ 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).^[4] It follows the Neogene Period and spans from 2.58 million years ago to the present.^[5] 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) although a third epoch, the Anthropocene, has been proposed but is not officially recognised by the ICS.^[5]

The Quaternary Period is typically defined by the cyclic growth and decay of continental ice sheets related to the Milankovitch cycles and the associated climate and environmental changes that they caused.^[6][7] 

Quaternary
2.58 – 0 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Mercator projection of the present-day Earth.

 

https://en.wikipedia.org/wiki/Quaternary 

https://geoltime.github.io/?Ma=1,900

The Tonian (from Ancient Greek: τόνος, romanized: tónos, meaning "stretch") is the first geologic period of the Neoproterozoic Era. It lasted from 1000 to 720 Mya (million years ago). Instead of being based on stratigraphy, these dates are defined by the ICS based on radiometric chronometry. The Tonian is preceded by the Stenian Period of the Mesoproterozoic Era and followed by the Cryogenian.

Rifting leading to the breakup of supercontinent Rodinia, which had formed in the mid-Stenian, occurred during this period, starting from 900 to 850 Mya. 

https://en.wikipedia.org/wiki/Tonian 

In geology, a rift is a linear zone where the lithosphere is being pulled apart^[1][2] and is an example of extensional tectonics.^[3]

Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side.^[4] Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems.

Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates.

Failed rifts are the result of continental rifting that failed to continue to the point of break-up. Typically the transition from rifting to spreading develops at a triple junction where three converging rifts meet over a hotspot. Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen. 

https://en.wikipedia.org/wiki/Rift

Diagram illustrating the structural relationship between grabens and horsts

Infrared-enhanced satellite image of a graben in the Afar Depression

In geology, a graben (/ˈɡrɑːbən/) is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. 

Etymology

Graben is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic context by Eduard Suess in 1883.^[1] The plural form is either graben^[2] or grabens.^[3]

^{https://en.wikipedia.org/wiki/Graben}

^{https://en.wikipedia.org/wiki/Rift_zone}

^{https://en.wikipedia.org/wiki/Chasm_(disambiguation)}

^{https://en.wikipedia.org/wiki/Rift_(disambiguation)}

Main tectonic plate boundaries – ridge (red), trench (green), fault (black) – and corresponding triple junctions (yellow dots)

 

 ^{https://en.wikipedia.org/wiki/Triple_junction}

Multi-junction (MJ) solar cells are solar cells with multiple p–n junctions made of different semiconductor materials. Each material's p-n junction will produce electric current in response to different wavelengths of light. The use of multiple semiconducting materials allows the absorbance of a broader range of wavelengths, improving the cell's sunlight to electrical energy conversion efficiency. 

https://en.wikipedia.org/wiki/Multi-junction_solar_cell

The Cryogenian (from Ancient Greek: κρύος, romanized: krýos, meaning "cold" and γένεσις, romanized: génesis, meaning "birth") is a geologic period that lasted from 720 to 635 million years ago.^[6] It forms the second geologic period of the Neoproterozoic Era, preceded by the Tonian Period and followed by the Ediacaran.

Cryogenian was the time of drastic biosphere changes. After the previous Boring Billion years of stability, at the beginning of Cryogenian the severe Sturtian glaciation began, freezing the entire Earth in a planetary state known as a Snowball Earth. After 70 million years it ended, but was quickly followed by the Marinoan glaciation, which was also a global event. These events are the subject of much scientific controversy specifically over whether these glaciations covered the entire planet or a band of open sea survived near the equator (termed "slushball Earth"). 

https://en.wikipedia.org/wiki/Cryogenian

A trace fossil, also known as an ichnofossil ( /ˈɪknoʊfɒsɪl/; from Greek: ἴχνος ikhnos "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. The study of such trace fossils is ichnology and is the work of ichnologists.

Trace fossils may consist of impressions made on or in the substrate by an organism. For example, burrows, borings (bioerosion), urolites (erosion caused by evacuation of liquid wastes), footprints and feeding marks and root cavities may all be trace fossils.

The term in its broadest sense also includes the remains of other organic material produced by an organism; for example coprolites (fossilized droppings) or chemical markers (sedimentological structures produced by biological means; for example, the formation of stromatolites). However, most sedimentary structures (for example those produced by empty shells rolling along the sea floor) are not produced through the behaviour of an organism and thus are not considered trace fossils.

The study of traces – ichnology – divides into paleoichnology, or the study of trace fossils, and neoichnology, the study of modern traces. Ichnological science offers many challenges, as most traces reflect the behaviour – not the biological affinity – of their makers. Accordingly, researchers classify trace fossils into form genera, based on their appearance and on the implied behaviour, or ethology, of their makers. 

 https://en.wikipedia.org/wiki/Trace_fossil

 https://en.wikipedia.org/wiki/Dinosaur_Footprints_Reservation

 

Not to be confused with Adaptive radiation.

An evolutionary radiation is an increase in taxonomic diversity that is caused by elevated rates of speciation,^[1] that may or may not be associated with an increase in morphological disparity.^[2] Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment, they are termed adaptive radiations.^[3]

 https://en.wikipedia.org/wiki/Evolutionary_radiation

The Great Ordovician Biodiversification Event (GOBE), was an evolutionary radiation of animal life throughout^[1] the Ordovician period, 40 million years after the Cambrian explosion,^[2] whereby the distinctive Cambrian fauna fizzled out to be replaced with a Paleozoic fauna rich in suspension feeder and pelagic animals.^[3]

It followed a series of Cambrian–Ordovician extinction events, and the resulting fauna went on to dominate the Palaeozoic relatively unchanged.^[4] Marine diversity increased to levels typical of the Palaeozoic,^[5] and morphological disparity was similar to today's.^[6][7] The diversity increase was neither global nor instantaneous; it happened at different times in different places.^[4] Consequently, there is unlikely to be a simple or straightforward explanation for the event; the interplay of many geological and ecological factors likely produced the diversification.^[1] 

Possible line of meteors (on the modern globe) associated with the Middle Ordovician meteor event 467.5±0.28 million years ago. Although this is suggestive of a single large meteorite shower, the exact alignment of continental plates 470 million years ago is unknown and the exact timing of meteors is also unknown.

 

https://en.wikipedia.org/wiki/Great_Ordovician_Biodiversification_Event

 

Illustration of the Taconic orogeny

The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the United States. As the mountain chain eroded in the Silurian and Devonian periods, sediments from the mountain chain spread throughout the present-day Appalachians and midcontinental North America.^[1]

 https://en.wikipedia.org/wiki/Taconic_orogeny

Reconstruction of how the Iapetus Ocean and surrounding continents might have been arranged during the late Ediacaran period

The Iapetus Ocean (/aɪˈæpɪtəs/; eye-AP-ih-təs)^[1] was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalonia. The ocean disappeared with the Acadian, Caledonian and Taconic orogenies, when these three continents joined to form one big landmass called Euramerica. The "southern" Iapetus Ocean has been proposed to have closed with the Famatinian and Taconic orogenies, meaning a collision between Western Gondwana and Laurentia.

Because the Iapetus Ocean was positioned between continental masses that would at a much later time roughly form the opposite shores of the Atlantic Ocean, it can be seen as a sort of precursor of the Atlantic, and the process by which it opened shares many similarities with that of the Atlantic's initial opening in the Jurassic.^[2] The Iapetus Ocean was therefore named for the titan Iapetus, who in Greek mythology was the father of Atlas, after whom the Atlantic Ocean was named.^[A]

 https://en.wikipedia.org/wiki/Iapetus_Ocean

Euramerica/Laurussia

Laurussia (left) during the closure of the Iapetus Ocean 430 Mya (middle Silurian) (view centred on 0°,-60°).

Euramerica in the Devonian

Laurentia remained almost static near the Equator throughout the early Palaeozoic, separated from Baltica by the up to 3,000 km (1,900 mi)-wide Iapetus Ocean.^[20] In the Late Cambrian, the mid-ocean ridge in the Iapetus Ocean subducted beneath Gondwana which resulted in the opening of a series of large back-arc basins. During the Ordovician, these basins evolved into a new ocean, the Rheic Ocean, which separated a series of terranes – Avalonia, Carolinia, and Armorica – from Gondwana.^[21]

Avalonia rifted from Gondwana in the Early Ordovician and collided with Baltica near the Ordovician–Silurian boundary (480–420 Mya). Baltica-Avalonia was then rotated and pushed north towards Laurentia. The collision between these continents closed the Iapetus Ocean and formed Laurussia, also known as Euramerica. Another historical term for this continent is the Old Red Continent or Old Red Sandstone Continent, in reference to abundant red beds of the Old Red Sandstone during the Devonian. The continent covered 37,000,000 km² (14,000,000 sq mi) including several large Arctic continental blocks.^[20][21]

With the Caledonian orogeny completed Laurussia was delimited thus:^[22]

• The eastern margin were the Barents Shelf and Moscow Platform;
• the western margin were the western shelves of Laurentia, later affected by the Antler orogeny;
• the northern margin was the Innuitian-Lomonosov orogeny which marked the collision between Laurussia and the Arctic Craton;
• and the southern margin was a Pacific-style active margin where the northward directed subduction of the ocean floor between Gondwana and Laurussia pushed continental fragments towards the latter.

During the Devonian (416-359 Mya) the combined landmass of Baltica and Avalonia rotated around Laurentia, which remained static near the Equator. The Laurentian warm, shallow seas and on shelves a diverse assemblage of benthos evolved, including the largest trilobites exceeding 1 m (3 ft 3 in). The Old Red Sandstone Continent stretched across northern Laurentia and into Avalonia and Baltica but for most of the Devonian a narrow seaway formed a barrier where the North Atlantic would later open. Tetrapods evolved from fish in the Late Devonian, with the oldest known fossils from Greenland. Low sea-levels during the Early Devonian produced natural barriers in Laurussia which resulted in provincialism within the benthic fauna. In Laurentia the Transcontinental Arch divided brachiopods into two provinces, with one of them confined to a large embayment west of the Appalachians. By the Middle Devonian, these two provinces had been united into one and the closure of the Rheic Ocean finally united faunas across Laurussia. High plankton productivity from the Devonian-Carboniferous boundary resulted in anoxic events that left black shales in the basins of Laurentia.^[23]

Pangaea

Main article: Pangaea

Pangaea formed during the closure of the Rheic Ocean 330 Mya (early Carboniferous) (view centred on 30°S,30°E)

The subduction of the Iapetus Ocean resulted in the first contact between Laurussia and Gondwana in the Late Devonian and terminated in full collision or the Hercynian/Variscan orogeny in the early Carboniferous (340 Mya).^[22] The Variscan orogeny closed the Rheic Ocean (between Avalonia and Armorica) and the Proto-Tethys Ocean (between Armorica and Gondwana) to form the supercontinent Pangaea.^[24] The Variscan orogeny is complex and the exact timing and the order of the collisions between involved microcontinents has been debated for decades.^[25]

Pangaea was completely assembled by the Permian except for the Asian blocks. The supercontinent was centred on the Equator during the Triassic and Jurassic, a period that saw the emergence of the Pangaean megamonsoon.^[26] Heavy rainfall resulted in high groundwater tables, in turn resulting in peat formation and extensive coal deposits.^[27]

During the Cambrian and Early Ordovician, when wide oceans separated all major continents, only pelagic marine organisms, such as plankton, could move freely across the open ocean and therefore the oceanic gaps between continents are easily detected in the fossil records of marine bottom dwellers and non-marine species. By the Late Ordovician, when continents were pushed closer together closing the oceanic gaps, benthos (brachiopods and trilobites) could spread between continents while ostracods and fishes remained isolated. As Laurussia formed during the Devonian and Pangaea formed, fish species in both Laurussia and Gondwana began to migrate between continents and before the end of the Devonian similar species were found on both sides of what remained of the Variscan barrier.^[28]

The oldest tree fossils are from the Middle Devonian pteridophyte Gilboa forest in central Laurussia (today New York, United States).^[29] In the late Carboniferous, Laurussia was centred on the Equator and covered by tropical rainforests, commonly referred to as the coal forest. By the Permian, the climate had become arid and these rainforests collapsed, lycopsids (giant mosses) were replaced by treeferns. In the dry climate a detritivorous fauna – including ringed worms, molluscs, and some arthropods – evolved and diversified, alongside other arthropods who were herbivorous and carnivorous, and tetrapods – insectivores and piscivores such as amphibians and early amniotes.^[30]

Laurasia

The Uralian orogeny and the formation of Laurasia 300, 280, and 240 Mya.
View centred on 25°N,35°E.

During the Carboniferous–Permian Siberia, Kazakhstan, and Baltica collided in the Uralian orogeny to form Laurasia.^[31]

The Palaezoic-Mesozoic transition was marked by the reorganisation of Earth's tectonic plates which resulted in the assembly of Pangaea, and eventually its break-up. Caused by the detachment of subducted mantle slabs, this reorganisation resulted in rising mantle plumes that produced large igneous provinces when they reached the crust. This tectonic activity also resulted in the Permian–Triassic extinction event. Tentional stresses across Eurasia developed into a large system of rift basins (Urengoy, East Uralian-Turgay and Khudosey) and flood basalts in the West Siberian Basin, the Pechora Basin, and South China.^[32]

Laurasia and Gondwana were equal in size but had distinct geological histories. Gondwana was assembled before the formation of Pangaea, but the assembly of Laurasia occurred during and after the formation of the supercontinent. These differences resulted in different patterns of basin formation and transport of sediments. East Antarctica was the highest ground within Pangaea and produced sediments that were transported across eastern Gondwana but never reached Laurasia. During the Palaeozoic, c. 30–40% of Laurasia but only 10–20% of Gondwana was covered by shallow marine water.^[33]

Asian blocks

Journey of the Asian blocks from Gondwana to Laurasia 450, 350, 300, and 200 Mya.
View centred on 0°S,105°E.

During the assembly of Pangaea Laurasia grew as continental blocks broke off Gondwana's northern margin; pulled by old closing oceans in front of them and pushed by new opening oceans behind them.^[34] During the Neoproterozoic-Early Paleozoic break-up of Rodinia the opening of the Proto-Tethys Ocean split the Asian blocks – Tarim, Qaidam, Alex, North China, and South China – from the northern shores of Gondwana (north of Australia in modern coordinates) and the closure of the same ocean reassembled them along the same shores 500–460 Mya resulting in Gondwana at its largest extent.^[21]

The break-up of Rodinia also resulted in the opening of the long-lived Paleo-Asian Ocean between Baltica and Siberia in the north and Tarim and North China in the south. The closure of this ocean is preserved in the Central Asian Orogenic Belt, the largest orogen on Earth.^[35]

North China, South China, Indochina, and Tarim broke off Gondwana during the Silurian-Devonian; Palaeo-Tethys opened behind them. Sibumasu and Qiantang and other Cimmerian continental fragments broke off in the Early Permian. Lhasa, West Burma, Sikuleh, southwest Sumatra, West Sulawesi, and parts of Borneo broke off during the Late Triassic-Late Jurassic.^[36]

During the Carboniferous and Permian, Baltica first collided with Kazakhstania and Siberia, then North China with Mongolia and Siberia. By the middle Carboniferous, however, South China had already been in contact with North China long enough to allow floral exchange between the two continents. The Cimmerian blocks rifted from Gondwana in the Late Carboniferous.^[31]

In the early Permian, the Neo-Tethys Ocean opened behind the Cimmerian terranes (Sibumasu, Qiantang, Lhasa) and, in the late Carboniferous, the Palaeo-Tethys Ocean closed in front. The eastern branch of the Palaeo-Tethys Ocean, however, remained opened while Siberia was added to Laurussia and Gondwana collided with Laurasia.^[34]

When the eastern Palaeo-Tethys closed 250–230 Mya, a series of Asian blocks – Sibumasu, Indochina, South China, Qiantang, and Lhasa – formed a separate southern Asian continent. This continent collided 240–220 Mya with a northern continent – North China, Qinling, Qilian, Qaidam, Alex, and Tarim – along the Central China orogen to form a combined East Asian continent. The northern margins of the northern continent collided with Baltica and Siberia 310–250 Ma, and thus the formation of the East Asian continent marked Pangaea at its greatest extent.^[34] By this time, the rifting of western Pangaea had already begun.^[31]

Flora and fauna

Pangaea split in two as the Tethys Seaway opened between Gondwana and Laurasia in the Late Jurassic. The fossil record, however, suggests the intermittent presence of a Trans-Tethys land bridge, though the location and duration of such a land bridge remains enigmatic.^[37]

Pine trees evolved in the early Mesozoic c. 250 Mya and the pine genus originated in Laurasia in the Early Cretaceous c. 130 Mya in competition with faster growing flowering plants. Pines adapted to cold and arid climates in environments where the growing season was shorter or wildfire common; this evolution limited pine range to between 31° and 50° north and resulted in a split into two subgenera: Strobus adapted to stressful environments and Pinus to fire-prone landscapes. By the end of the Cretaceous pines were established across Laurasia, from North America to East Asia.^[38]

From the Triassic to the Early Jurassic, before the break-up of Pangaea, archosaurs (crurotarsans, pterosaurs and dinosaurs including birds) had a global distribution, especially crurotarsans, the group ancestral to the crocodilians. This cosmopolitanism ended as Gondwana fragmented and Laurasia was assembled. Pterosaur diversity reach a maximum in the Late Jurassic—Early Cretaceous and plate tectonic didn't affect the distribution of these flying reptiles. Crocodilian ancestors also diversified during the Early Cretaceous but were divided into Laurasian and Gondwanan populations; true crocodilians evolved from the former. The distribution of the three major groups of dinosaurs – the sauropods, theropods, and ornithischians – was similar that of the crocodilians. East Asia remained isolated with endemic species including psittacosaurs (horned dinosaurs) and Ankylosauridae (club-tailed, armoured dinosaurs).^[39]

Meanwhile, mammals slowly settled in Laurasia from Gondwana in the Triassic, the latter of which was the living area of their Permian ancestors. They split in two groups, with one returning to Gondwana (and stayed there after Pangaea split) while the other staying in Laurasia (until further descendants switched to Gondwana starting from the Jurassic).

In the early Eocene a peak in global warming led to a pan-Arctic fauna with alligators and amphibians present north of the Arctic Circle. In the early Palaeogene, landbridges still connected continents, allowing land animals to migrate between them. On the other hand, submerged areas occasionally divided continents: the Turgai Sea separated Europe and Asia from the Middle Jurassic to the Oligocene and as this sea or strait dried out, a massive faunal interchange took place and the resulting extinction event in Europe is known as the Grande Coupure.^[40]

The Coraciiformes (an order of birds including kingfishers) evolved in Laurasia. While this group now has a mostly tropical distribution, they originated in the Arctic in the late Eocene c. 35 Mya from where they diversified across Laurasia and farther south across the Equator.^[41]

The placental mammal group of Laurasiatheria is named after Laurasia.

Final split

Opening of the North Atlantic Ocean 90, 50, and 30 Mya.

In the Triassic–Early Jurassic (c. 200 Mya), the opening of the Central Atlantic Ocean was preceded by the formation of a series of large rift basins, such as the Newark Basin, between eastern North America, from what is today the Gulf of Mexico to Nova Scotia, and in Africa and Europe, from Morocco to Greenland.^[42]

By c. 83 Mya spreading had begun in the North Atlantic between the Rockall Plateau, a continental fragment sitting on top of the Eurasian Plate, and North America. By 56 Mya Greenland had become an independent plate, separated from North America by the Labrador Sea-Baffin Bay Rift. By 33 Mya spreading had ceased in the Labrador Sea and relocated to the Mid-Atlantic Ridge.^[43] The opening of the North Atlantic Ocean had effectively broken Laurasia in two.

See also

Look up Laurasia in Wiktionary, the free dictionary.

• Laurasiatheria
• Laurasiformes

References

Notes

1. 
   

Oxford English Dictionary

Du Toit 1937, p. 40

Torsvik & Cocks 2004, Laurussia and Laurasia, pp. 558, 560

Torsvik et al. 2012, From Laurentia to Laurussia and Laurasia: Overview, p. 6

Meert 2012, pp. 991–992

Ziegler 1988, Abstract

Bleeker 2003, p. 108

Zhao et al. 2004, Abstract

Zhao et al. 2004, Summary and Discussion, pp. 114–115

Zhao et al. 2002, Laurentia (North America and Greenland) and Baltica, pp. 145-149

Ernst et al. 2013, Progress on continental reconstructions, pp. 8–9

"Consensus" reconstruction from Li et al. 2008.

Torsvik et al. 1996, Rodinia, pp. 236–237

Li et al. 2008, Siberia–Laurentia connection, p. 189

Yarmolyuk et al. 2006, p. 1031; Fig. 1, p. 1032

Torsvik et al. 1996, Abstract; Initial break-up of Rodinia and Vendian glaciations, pp. 237–240

Scotese 2009, p. 71

Stampfli 2000, Palaeotethys, p. 3

Scotese 2009, The break-up of Pannotia, p. 78

Torsvik et al. 2012, p. 16

Zhao et al. 2018, Closure of Proto-Tethys Ocean and the first assembly of East Asian blocks at the northern margin of Gondwana, pp. 7-10

Ziegler 2012, Introduction, pp. 1–4

Cocks & Torsvik 2011, Facies and faunas, pp. 10–11

Rey, Burg & Casey 1997, Introduction, pp. 1–2

Eckelmann et al. 2014, Introduction, pp. 1484–1486

Parrish 1993, Paleogeographic Evolution of Pangea, p. 216

Parrish 1993, Geological Evidence of the Pangean Megamonsoon, p. 223

McKerrow et al. 2000, The narrowing oceans, pp. 10–11

Lu et al. 2019, pp. 1–2

Sahney, Benton & Falcon-Lang 2010, Introduction, p. 1079

Blakey 2003, Assembly of Western Pangaea: Carboniferous–Permian, pp. 453–454; Assembly of Eastern Pangaea: Late Permian–Jurassic, p. 454; Fig. 10, p. 454

Nikishin et al. 2002, Introduction, pp. 4–5; Fig. 4, p. 8

Rogers & Santosh 2004, Differences Between Gondwana and Laurasia in Pangea, pp. 127, 130

Zhao et al. 2018, Closure of Paleo-Tethys Ocean and assembly of Pangea with East Asian blocks, pp. 14-16

Zhao et al. 2018, Closure of Paleo-Asian Ocean: collision of Tarim, Alex and North China with East Europe and Siberia, pp. 11-14

Metcalfe 1999, pp. 15–16

Gheerbrant & Rage 2006, Introduction, p. 225

Keeley 2012, Introduction, pp. 445–446; Mesozoic origin and diversification, pp. 450–451

Milner, Milner & Evans 2000, p. 319

Milner, Milner & Evans 2000, p. 328

McCullough et al. 2019, Conclusion, p. 7

Olsen 1997, Introduction, p. 338

43. Seton et al. 2012, Rockall–North America/Greenland, p. 222

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• Bleeker, W. (2003). "The late Archean record: a puzzle in ca. 35 pieces" (PDF). Lithos. 71 (2–4): 99–134. Bibcode:2003Litho..71...99B. doi:10.1016/j.lithos.2003.07.003. Retrieved 22 December 2019.
• Cocks, L. R. M.; Torsvik, T. H. (2011). "The Palaeozoic geography of Laurentia and western Laurussia: a stable craton with mobile margins". Earth-Science Reviews. 106 (1–2): 1–51. Bibcode:2011ESRv..106....1C. CiteSeerX 10.1.1.663.2972. doi:10.1016/j.earscirev.2011.01.007.
• Du Toit, A. L. (1937). Our wandering continents : an hypothesis of continental drifting. Edinburgh: Oliver and Boyd. ISBN 9780598627582.
• Eckelmann, K.; Nesbor, H. D.; Königshof, P.; Linnemann, U.; Hofmann, M.; Lange, J. M.; Sagawe, A. (2014). "Plate interactions of Laurussia and Gondwana during the formation of Pangaea—Constraints from U–Pb LA–SF–ICP–MS detrital zircon ages of Devonian and Early Carboniferous siliciclastics of the Rhenohercynian zone, Central European Variscides". Gondwana Research. 25 (4): 1484–1500. Bibcode:2014GondR..25.1484E. doi:10.1016/j.gr.2013.05.018.
• Ernst, R. E.; Bleeker, W.; Söderlund, U.; Kerr, A. C. (2013). "Large Igneous Provinces and supercontinents: Toward completing the plate tectonic revolution". Lithos. 174: 1–14. Bibcode:2013Litho.174....1E. doi:10.1016/j.lithos.2013.02.017. Retrieved 28 December 2019.
• Gheerbrant, E.; Rage, J. C. (2006). "Paleobiogeography of Africa: how distinct from Gondwana and Laurasia?". Palaeogeography, Palaeoclimatology, Palaeoecology. 241 (2): 224–246. Bibcode:2006PPP...241..224G. doi:10.1016/j.palaeo.2006.03.016.
• Keeley, J. E. (2012). "Ecology and evolution of pine life histories" (PDF). Annals of Forest Science. 69 (4): 445–453. doi:10.1007/s13595-012-0201-8. S2CID 18013787. Retrieved 22 February 2020.
• Li, Z. X.; Bogdanova, S. V.; Collins, A. S.; Davidson, A.; De Waele, B.; Ernst, R. E.; Fitzsimons, I. C. W.; Fuck, R. A.; Gladkochub, D. P.; Jacobs, J.; Karlstrom, K. E.; Lul, S.; Natapov, L. M.; Pease, V.; Pisarevsky, S. A.; Thrane, K.; Vernikovsky, V. (2008). "Assembly, configuration, and break-up history of Rodinia: A synthesis" (PDF). Precambrian Research. 160 (1–2): 179–210. Bibcode:2008PreR..160..179L. doi:10.1016/j.precamres.2007.04.021. Retrieved 10 April 2020.
• Lu, M.; Lu, Y.; Ikejiri, T.; Hogancamp, N.; Sun, Y.; Wu, Q.; Carroll, R.; Çemen, I.; Pashin, J. (2019). "Geochemical evidence of First Forestation in the southernmost euramerica from Upper Devonian (Famennian) Black shales". Scientific Reports. 9 (1): 7581. Bibcode:2019NatSR...9.7581L. doi:10.1038/s41598-019-43993-y. PMC 6527553. PMID 31110279.
• McKerrow, W. S.; Mac Niocaill, C.; Ahlberg, P. E.; Clayton, G.; Cleal, C. J.; Eagar, R. M. C. (2000). "The late Palaeozoic relations between Gondwana and Laurussia". Geological Society, London, Special Publications. 179 (1): 9–20. Bibcode:2000GSLSP.179....9M. doi:10.1144/GSL.SP.2000.179.01.03. S2CID 129789533. Retrieved 18 January 2020.
• McCullough, J. M.; Moyle, R. G.; Smith, B. T.; Andersen, M. J. (2019). "A Laurasian origin for a pantropical bird radiation is supported by genomic and fossil data (Aves: Coraciiformes)". Proceedings of the Royal Society B. 286 (1910): 20190122. doi:10.1098/rspb.2019.0122. PMC 6742990. PMID 31506056.
• Meert, J. G. (2012). "What's in a name? The Columbia (Paleopangaea/Nuna) supercontinent" (PDF). Gondwana Research. 21 (4): 987–993. Bibcode:2012GondR..21..987M. doi:10.1016/j.gr.2011.12.002. Retrieved 22 December 2019.
• Metcalfe, I. (1999). "Gondwana dispersion and Asian accretion: an overview". In Metcalfe, I. (ed.). Gondwana Dispersion and Asian Accretion. IGCP 321 final results volume. Rotterdam: A.A. Balkema. pp. 9–28. doi:10.1080/08120099608728282. ISBN 90-5410-446-5.
• Milner, A. C.; Milner, A. R.; Evans, S. E. (2000). "Amphibians, reptiles and birds: a biogeographical review". In Culver, S. J.; Rawson, P. F. (eds.). Biotic Response to Global Change-The Last Million Years. Cambridge University Press. pp. 316–332. ISBN 0-511-04068-7.
• Nikishin, A. M.; Ziegler, P. A.; Abbott, D.; Brunet, M. F.; Cloetingh, S. A. P. L. (2002). "Permo–Triassic intraplate magmatism and rifting in Eurasia: implications for mantle plumes and mantle dynamics". Tectonophysics. 351 (1–2): 3–39. Bibcode:2002Tectp.351....3N. doi:10.1016/S0040-1951(02)00123-3. Retrieved 15 February 2020.
• Olsen, P. E. (1997). "Stratigraphic record of the early Mesozoic breakup of Pangea in the Laurasia-Gondwana rift system" (PDF). Annual Review of Earth and Planetary Sciences. 25 (1): 337–401. Bibcode:1997AREPS..25..337O. doi:10.1146/annurev.earth.25.1.337. Retrieved 1 December 2019.
• Parrish, J. T. (1993). "Climate of the supercontinent Pangea". The Journal of Geology. 101 (2): 215–233. Bibcode:1993JG....101..215P. doi:10.1086/648217. S2CID 128757269. Retrieved 26 November 2019.
• Rey, P.; Burg, J. P.; Casey, M. (1997). "The Scandinavian Caledonides and their relationship to the Variscan belt". Geological Society, London, Special Publications. 121 (1): 179–200. Bibcode:1997GSLSP.121..179R. doi:10.1144/GSL.SP.1997.121.01.08. S2CID 49353621. Retrieved 23 November 2019.
• Rogers, J. J.; Santosh, M. (2004). Continents and supercontinents. Gondwana Research. Vol. 7. Oxford University Press. p. 653. Bibcode:2004GondR...7..653R. doi:10.1016/S1342-937X(05)70827-3. ISBN 9780195347333.
• Scotese, C. R. (2009). "Late Proterozoic plate tectonics and palaeogeography: a tale of two supercontinents, Rodinia and Pannotia". Geological Society, London, Special Publications. 326 (1): 67–83. Bibcode:2009GSLSP.326...67S. doi:10.1144/SP326.4. S2CID 128845353. Retrieved 10 November 2019.
• Seton, M.; Müller, R. D.; Zahirovic, S.; Gaina, C.; Torsvik, T.; Shephard, G.; Talsma, A.; Gurnis, M.; Maus, S.; Chandler, M. (2012). "Global continental and ocean basin reconstructions since 200Ma". Earth-Science Reviews. 113 (3): 212–270. Bibcode:2012ESRv..113..212S. doi:10.1016/j.earscirev.2012.03.002. Retrieved 1 December 2019.
• Sahney, S.; Benton, M. J.; Falcon-Lang, H. J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology. 38 (12): 1079–1082. doi:10.1130/G31182.1. Retrieved 22 March 2020.
• Stampfli, G. M. (2000). "Tethyan oceans" (PDF). Geological Society, London, Special Publications. 173 (1): 1–23. Bibcode:2000GSLSP.173....1S. doi:10.1144/GSL.SP.2000.173.01.01. S2CID 219202298. Retrieved 30 November 2019.
• Torsvik, T. H.; Cocks, L. R. M. (2004). "Earth geography from 400 to 250 Ma: a palaeomagnetic, faunal and facies review" (PDF). Journal of the Geological Society. 161 (4): 555–572. Bibcode:2004JGSoc.161..555T. doi:10.1144/0016-764903-098. S2CID 128812370. Retrieved 25 January 2020.
• Torsvik, T. H.; Smethurst, M. A.; Meert, J. G.; Van der Voo, R.; McKerrow, W. S.; Brasier, M. D.; Sturt, B. A.; Walderhaug, H. J. (1996). "Continental break-up and collision in the Neoproterozoic and Palaeozoic—a tale of Baltica and Laurentia" (PDF). Earth-Science Reviews. 40 (3–4): 229–258. Bibcode:1996ESRv...40..229T. doi:10.1016/0012-8252(96)00008-6. Retrieved 22 December 2019.
• Torsvik, T. H.; Van der Voo, R.; Preeden, U.; Mac Niocaill, C.; Steinberger, B.; Doubrovine, P. V.; van Hinsbergen, D. J. J.; Domeier, M.; Gaina, C.; Tohver, E.; Meert, J. G.; McCausland, P. J. A.; Cocks, R. M. (2012). "Phanerozoic polar wander, palaeogeography and dynamics" (PDF). Earth-Science Reviews. 114 (3–4): 325–368. Bibcode:2012ESRv..114..325T. doi:10.1016/j.earscirev.2012.06.007. hdl:10852/62957. Retrieved 9 November 2019.
• Yarmolyuk, V. V.; Kovalenko, V. I.; Sal'nikova, E. B.; Nikiforov, A. V.; Kotov, A. B.; Vladykin, N. V. (2006). "Late Riphean rifting and breakup of Laurasia: data on geochronological studies of ultramafic alkaline complexes in the southern framing of the Siberian craton". Doklady Earth Sciences. 404 (7): 1031–1036. Retrieved 1 December 2019.
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• Carboniferous paleogeography
• Permian paleogeography
• Mesozoic paleogeography
• Paleocene paleogeography
• Natural history of North America
• Mesozoic North America
• Geology of Greenland
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Category:Carboniferous paleogeography

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From Wikipedia, the free encyclopedia

See also the preceding Category:Devonian paleogeography and the succeeding Category:Permian paleogeography

Wikimedia Commons has media related to Carboniferous palaeogeography.

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This category has the following 2 subcategories, out of 2 total.

C

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• Carboniferous orogenies‎ (1 C, 10 P)

S

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• Carboniferous System‎ (8 C)

Pages in category "Carboniferous paleogeography"

The following 8 pages are in this category, out of 8 total. This list may not reflect recent changes.

C

• Cathaysia
• Cimmeria (continent)
• Coal forest

L

• Laurasia

P

• Pangaea
• Proto-Tethys Ocean

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U

• Ural Ocean

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• Paleozoic paleogeography
• Paleogeography

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Coal forests were the vast swathes of wetlands that covered much of the Earth's tropical land areas during the late Carboniferous (Pennsylvanian) and Permian times.^[1][2] As plant matter from these forests decayed, enormous deposits of peat accumulated, which later changed into coal.

Much of the carbon in the peat deposits produced by coal forests came from photosynthetic splitting of existing carbon dioxide, which released the accompanying split-off oxygen into the atmosphere. This process may have greatly increased the oxygen level, possibly as high as about 35%, making the air more easily breathable by animals with inefficient respiratory systems, as indicated by the size of Meganeura compared to modern dragonflies.^[3]

Coal forests covered tropical Euramerica (Europe, eastern North America, northwesternmost Africa) and Cathaysia (mainly China). Climate change devastated these tropical rainforests during the Carboniferous period. The Carboniferous rainforest collapse was caused by a cooler drier climate that initially fragmented, then collapsed the rainforest ecosystem.^[2] During most of the rest of Carboniferous times, the coal forests were mainly restricted to refugia in North America (such as the Appalachian and Illinois coal basins) and central Europe.

At the very end of the Carboniferous period, the coal forests underwent a resurgence, expanding mainly in eastern Asia, notably China; they never recovered fully in Euramerica. The Chinese coal forests continued to flourish well into Permian times. This resurgence of the coal forests in very late Carboniferous times seems to have coincided with a lowering of global temperatures and a return of extensive polar ice in southern Gondwana, perhaps due to lessening of the greenhouse effect as the massive coal deposition process extracted carbon dioxide from the atmosphere.

Environment

Coal forest of tree ferns and lycopod trees, in a 1906 artist's rendering

The coal forests seem to have been areas of flat, low-lying swampy areas with rivers flowing through from higher, drier land.^[4] When the rivers flooded, silt gradually built up into natural levees. Lakes formed as some areas subsided, while formerly wet areas became dry from silt buildups. When a forested area became dry enough to be set on fire by lightning, the resulting forest fire left charcoal, the fusain component of coal.

Plant life

There seems to have been a rich and varied flora, with sets of species for each type of growing condition. The most varied flora seems to have been leave^{[clarification needed]} vegetation, with many species of trees, bushes, creepers, etc. Thickets of Calamites seem to have favored the edges of lakes and waterways. Lycopsid genera specialized in various roles: Paralycopodites as a pioneer on newly silted lakes shallow enough for land vegetation to start; Diaphorodendron later when the ground had become peaty. Other species specialized in re-settling land which had been briefly deforested by flooding: Synchysidendron and Lepidodendron in mineral-soil areas and Lepidophloios in peat areas. Cordaites may have favored drier areas of the swamp. One author^[who?] thinks that Sigillaria favored the intermediate areas between levee habitat and swamp habitat. In the later part of this period tree ferns tended to take over from lycopsid trees.

Some of the characteristic plants of the coal forests were:

• Sigillaria
• Lepidodendron
• Calamites
• pteridosperms

British coal forest fossils

Genera recorded in Great Britain include:^[4]

• Pteridosperm leaves: Alethopteris, Callipteridium, Cyclopteris (leaf bases), ?Desmopteris, Dicksonites, Eusphenopteris, Fortopteris, Hymenophyllites, Karinopteris, Laveinopteris, Linopteris, Lonchopteris, Lyginopteris, Macroneuropteris, Margaritopteris, Mariopteris, Neuralethopteris, Neuropteris, Odontopteris, Palmatopteris, Paropteris, Reticulopteris
• Pteridosperm spore organs: Aulacotheca (male), Boulaya, Potoniea (male), Whittleseya (male)
• Pteridosperm seeds: Gnetopsis, Hexagonocarpus, Holcospermum, Lagenospermum, ?Polypterocarpus, Rhabdocarpus, Trigonocarpus
• Fern fronds: Aphlebia, Bertrandia, Corynepteris, Crossotheca, Cyathocarpus, Lobatopheris, Oligocarpia, Pecopteris, Polymorphopteris, Renaultia, Sphyropteris, Sturia, Zeilleria
• Tree-fern leaves: Caulopteris
• Tree-fern stems: Artisophyton, Megaphyton
• Lycopsid tree stems and leafy shoots: Cyperites, Lepidodendron, Ulodendron
• Lycopsid tree stems: Asolanus, Bothrodendron, Cyclostigma, Lepidophloios, Sigillaria, Sublepidophloios, Syringodendron (de-barked)
• Lycopsid reproductive parts: Flemingites, Lepidodostrobus, Lepidodostrobophyllum (sporophylls), Sigillariostrobus
• Lycopsid (herbaceous) stems: Lycopodites, Selaginellites
• Sphenopsid leaves: Annularia, Asterophyllites
• Sphenopsid stems: Calamites
• Sphenopsid reproductive parts: Bowmanites, Calamostachys, Macrostachya, Palaeostachya
• Cordaite leaves: Cordaites
• Cordaite stem pith case: Artisia (pith cast)
• Cordaite seeds: Cordaicarpus
• Cordaite cones and seeds: Cordaitanthus
• May be progymnosperm: leaves: Noeggerathia
• Conifer leaves: Walchia
• Seeds: Carpolithus, Cornucarpus, Samaropsis

Palaeontologists have described many species for some of these genera, e.g. (in Britain): Sigillaria 33, Lepidodendron 19, Alethopteris (pteridosperm leaves) 11, Calamites 8.

Some easily identified species occur over a wide area but only for a small part of the coal-forming period, and are thus useful as zone fossils.

Animal life

Animals inhabiting the coal forests were invertebrates (particularly insects), fish, labyrinthodont amphibians, and early reptiles. Amphibians were widespread, but once the coal forests fragmented, the new environment was better suited to reptiles, which became more diverse and even varied their diet in the rapidly changing environment.^[2]

See also

These films and TV series are set partly in coal forests:

• Prehistoric Park Episode 5: ("The Bug House")
• Walking with Monsters Episode Two: "Reptile's Beginnings"

References

1. 
   

Cleal, C. J. & Thomas, B. A. (2005). "Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?" Geobiology, 3, p. 13-31.

Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica" (PDF). Geology. 38 (12): 1079–1082. doi:10.1130/G31182.1.

Schneider; et al. (2002). "Insect size in the Carboniferous in contrast with contemporary analogues: a reflection of atmospheric oxygen content". International Journal of Paleoecology. 15 (21): 168–192.

4. Christopher J. Cleal; Barry A.Thomas (1994). Plant Fossils of the British Coal Measures. The Palaeontological Association. ISBN 0-901702-53-6.

External links to reconstruction images of coal forest

• Coal forest. Department of Earth and Environmental Sciences, The Open University. Retrieved January 6, 2012.
• Coal Forest Reconstruction. Burpee Museum of Natural History (March 2000). Retrieved January 6, 2012.
• "The Carboniferous Period". Geologic time scale. University of California Museum of Paleontology. Retrieved January 6, 2012.
• Image from Das Rektorat der WWU Münster. Westfalische Wilhelms-Universitat Munster. Retrieved January 6, 2012.

Categories:

• Carboniferous paleogeography
• Carboniferous life

 

https://en.wikipedia.org/wiki/Coal_forest

 

 

From Wikipedia, the free encyclopedia

Not to be confused with the Ural Sea.

The Ural Ocean (also called the Uralic Ocean) was a small, ancient ocean that was situated between Siberia and Baltica.^[1] The ocean formed in the Late Ordovician epoch, when large islands from Siberia collided with Baltica, which was then part of the landmass Euramerica. The islands also caused Ural Ocean's precursor, Khanty Ocean to close.^[2] By the Devonian Period, however, Ural Ocean begins to shrink because the Siberian continent and Kazakhstania microcontinent were closing in to Baltica. In the Latest Devonian to Mississippian periods, Ural Ocean became a seaway. Until the three collided in the Carboniferous, it created the Ural Mountains, completely closing the ocean, and forming the Pangaea supercontinent.

See also

• List of ancient oceans – List of Earth's former oceans
• Uralian orogeny – Long series of linear deformation and mountain building events that raised the Ural Mountains

References

1. 
   

Levashova, N. M.; Degtyarev, K. E.; van der Voo, R.; Bazhenov, M. L.; Mikolaichuk, A. V.; McCausland, P. J. (2005-12-01). "What did the Ural Ocean look like?". 2005: GP13B–04. Bibcode:2005AGUFMGP13B..04L.

2. Lin, Jia'en (2020-07-11). Proceedings of the International Field Exploration and Development Conference 2019. Springer Nature. pp. 3170–3173. ISBN 978-981-15-2485-1.

This palaeogeography article is a stub. You can help Wikipedia by expanding it.

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• Silurian bodies of water
• Devonian paleogeography
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https://en.wikipedia.org/wiki/language_need_to_survive

https://en.wikipedia.org/wiki/charity

https://en.wikipedia.org/wiki/false_charity_americans

https://en.wikipedia.org/wiki/euthanasia_authorities_vet_his

 https://en.wikipedia.org/wiki/Special_operations

https://en.wikipedia.org/wiki/Special_forces_women

https://en.wikipedia.org/wiki/Special_forces

https://en.wikipedia.org/wiki/uare

https://en.wikipedia.org/wiki/bomers_before_america_inclusion_clause

https://en.wikipedia.org/wiki/american_identification_want

https://en.wikipedia.org/wiki/bombers

https://en.wikipedia.org/wiki/builder_rebuild

https://en.wikipedia.org/wiki/brain_surgeon_record

https://en.wikipedia.org/wiki/surprise_death_disease

https://en.wikipedia.org/wiki/bioweapons_physics-surprise

https://en.wikipedia.org/wiki/equipment-theft-usa

https://en.wikipedia.org/wiki/siberia-drbetteydvm-dactadiobeatles-sorcers-strone

https://en.wikipedia.org/wiki/austrailia-dusty-blue-mem-box-nobt

https://en.wikipedia.org/wiki/BTR

https://en.wikipedia.org/wiki/rebodiment-trace-deluge-of-escape

https://en.wikipedia.org/wiki/rec-req

https://en.wikipedia.org/wiki/mister-reveal

https://en.wikipedia.org/wiki/russ-maf

https://en.wikipedia.org/wiki/baby-putty-nlab-nati-natty-aphrodite-venus-etc.-indep

https://en.wikipedia.org/wiki/above-your-honor

https://en.wikipedia.org/wiki/global-amnesia-aphasia-building-women-right

https://en.wikipedia.org/wiki/Secret_police

https://en.wikipedia.org/wiki/goth-qui

https://en.wikipedia.org/wiki/old-gangs

https://en.wikipedia.org/wiki/valley-people-illyo-daryo

https://en.wikipedia.org/wiki/justin-church-early-scholars-family-people-saints-sinners-zak-etc.

https://en.wikipedia.org/wiki/first-police-shaun-first-king-etc.

https://en.wikipedia.org/wiki/steve-adam-and-eve-of-swedel-denmark-var-clones-etc.-wolrd-hist

https://en.wikipedia.org/wiki/romaniov-marx-expulsion-impersonation-etc.

https://en.wikipedia.org/wiki/forgery-forg-fog-forgotten-titles-amnesia-plis-etc.

https://en.wikipedia.org/wiki/overlap-same-similar-deception-etc.

https://en.wikipedia.org/wiki/human-trafficking-ring-scheme-usa-et-al-etc.

https://en.wikipedia.org/wiki/abduction-break-enter-diw-amnestic-drug-brain-transplant-hybrid-implant-dconstmat-missing-men-missing-builders-missing-etc.

https://en.wikipedia.org/wiki/clone-cloak-etc.

https://en.wikipedia.org/wiki/price-to-plac-etc.

https://en.wikipedia.org/wiki/List_of_historical_secret_police_organizations

https://en.wikipedia.org/wiki/kill-comp-rebuild-comp-men-etc.

https://en.wikipedia.org/wiki/prison-result-etc.

https://en.wikipedia.org/wiki/stolen-asset-etc.

https://en.wikipedia.org/wiki/rescues-etc.

https://en.wikipedia.org/wiki/blank-slate-etc.

https://en.wikipedia.org/wiki/Standing_army

https://en.wikipedia.org/wiki/Vacuum_chamber

https://en.wikipedia.org/wiki/Celts

https://en.wikipedia.org/wiki/Anatolia

https://en.wikipedia.org/wiki/Gulf_of_Alexandretta

https://en.wikipedia.org/wiki/Jesus_in_Christianity

https://en.wikipedia.org/wiki/%C4%B0skenderun

https://en.wikipedia.org/wiki/Roman_Catholic

https://en.wikipedia.org/wiki/Principality_of_Antioch

The megas doux (Greek: μέγας δούξ, pronounced [ˈmeɣaz ˈðuks], "grand duke") was one of the highest positions in the hierarchy of the later Byzantine Empire, denoting the commander-in-chief of the Byzantine navy. It is sometimes also given in English by the half-Latinizations megaduke or megadux.^[1] The Greek word δούξ is the Hellenized form of the Latin term dux, meaning leader or commander. 

https://en.wikipedia.org/wiki/Megas_doux 

Tzachas (Greek: Τζαχᾶς, romanized: Tzachás), also known as Chaka Bey (Turkish: Çaka Bey)^{[dn 1]} was an 11th-century Seljuk Turkish military commander who ruled an independent state based in Smyrna. Originally in Byzantine service, he rebelled and seized Smyrna, much of the Aegean coastlands of Asia Minor and the islands lying off shore in 1088–91. At the peak of his power, he even declared himself Byzantine emperor, and sought to assault Constantinople in conjunction with the Pechenegs. In 1092, a Byzantine naval expedition under John Doukas inflicted a heavy defeat on him and retook Lesbos, while in the next year he was treacherously slain by his son-in-law Kilij Arslan I. Smyrna and the rest of Tzachas' former domain were recovered by the Byzantines a few years later, in c. 1097.

https://en.wikipedia.org/wiki/Tzachas

Anna Komnene (Greek: Ἄννα Κομνηνή, romanized: Ánna Komnēnḗ; 1 December 1083 – 1153^[1]), commonly Latinized as Anna Comnena,^[2] was a Byzantine princess and author of the Alexiad, an account of the reign of her father, the Byzantine emperor, Alexios I Komnenos. The Alexiad is the most important primary source of Byzantine history of the late 11th and early 12th centuries. Although she is best known as the author of the Alexiad, Anna played an important part in the politics of the time and attempted to depose her brother, John II Komnenos, as emperor and seize the throne herself.^[3] 

https://en.wikipedia.org/wiki/Anna_Komnene

Grand prince or great prince (feminine: grand princess or great princess) (Latin: magnus princeps; Swedish: Storfurste; Greek: megas archon; Russian: великий князь, romanized: velikiy knyaz) is a title of nobility ranked in honour below emperor, equal of king or archduke and above a sovereign prince.  

https://en.wikipedia.org/wiki/Grand_prince

https://en.wikipedia.org/wiki/Primus_inter_pares

https://en.wikipedia.org/wiki/Prison

https://en.wikipedia.org/wiki/Russian_mafia

https://en.wikipedia.org/wiki/Gulag

https://en.wikipedia.org/wiki/Prisoner-of-war_camp

https://en.wikipedia.org/wiki/Internment

 

https://en.wikipedia.org/wiki/Escalation_of_commitment

https://en.wikipedia.org/wiki/Privilege_escalation

https://en.wikipedia.org/wiki/Escalation_archetype

https://en.wikipedia.org/wiki/Escalation_clause

https://en.wikipedia.org/wiki/Conflict_escalation

https://en.wikipedia.org/wiki/Weapon_of_mass_destruction

https://en.wikipedia.org/wiki/Nuclear_escalation

https://en.wikipedia.org/wiki/Russian_invasion_of_Ukraine

https://en.wikipedia.org/wiki/Technology_during_World_War_II

https://en.wikipedia.org/wiki/Logistics

https://en.wikipedia.org/wiki/Gross_domestic_product

https://en.wikipedia.org/wiki/Extinction_event?wprov=srpw1_2#Clathrate_gun_hypothesis

https://en.wikipedia.org/wiki/Gateway_drug_effect

Black Egyptian hypothesis

Further information: Kerma culture, Kingdom of Kush, and Twenty-fifth Dynasty of Egypt

The Black Egyptian hypothesis is the hypothesis that ancient Egypt was a "Black", homogeneous civilization.^[229][230] At a UNESCO symposium in 1974 there was consensus that Ancient Egypt was indigenous to Africa.^[35]

However, Professor Diop's hypothesis that Ancient Egypt was a "Black" civilization was met with "numerous objections" in 1974 which revealed "a disagreement which remained profound even though it was not voiced explicitly. In respect of certain sequences, the criticisms arose out of the line of argument put forward."^[231] The majority of the objections "raised were of methodological nature" which ranged from the need for reliable statistical data to further research projects in several fields such as archaeology and physical anthropology before final conclusions on the peopling of Egypt could be made.^[232] There was also "total disagreement" from the majority of scholars in the 1974 conference^[39] on the hypothesis that Ancient Egypt had been a homogenous population until Persian times with several scholars favouring the hypothesis of a mixed population.^[233][234]

Subsequent reviewers of the 1974 symposium debate and the UNESCO publication have presented a range of views on the outcome of the debate.^{[40][41][42][235]}Larissa Nordholt argued that Diop's chapter was politically motivated, having been published only due to being in line with UNESCO's political imperatives, despite clashing with accepted historical methods and standards of academic rigor. Nordholdt argued that Diop's views aligned with the decolonization efforts of the General History of Africa but that he premised his arguments on outdated, racialism which classified humanity into distinct groups with a biological essence. However, she did state that the contributors did “come to a general consensus that the Egyptians could not not have been “white” in the same way that Europeans were” and the dissemination of Diop’s ideas contributed to a wider recognition that the Ancient Egypt was an African civilisation although his methods were “not considered entirely permissible by most of the other GHA historians”^[45] According to Larissa Nordholdt, "Many reviewers, however, still objected to what they identified as an overtly political ideology within the GHA. They did not necessarily object to the flavour of that ideology, but rather to the presence of a political agenda as such. Often Diop’s chapter seemed to serve as a catalyst for that sentiment".^{[44]: 268–279} Peter Shinnie reviewing the General History of Africa volume, wrote that "It seems that UNESCO and [the editor] Mokhtar were embarassed by the unscholarly and preposterous nature of Diop's views but were unable to reject his contribution".^[46] However, Bethwell Allan Ogot, a Kenyan historian and editor of UNESCO General History of Africa Volume 5, stated that “Cheikh Anta Diop wrested Egyptian civilization from the Egyptologists and restored it to the mainstream of African history”.^[236] Stephen Quirke argued that the UNESCO-sponsored conference on the General History of Africa in 1974 "did not change the Eurocentric climate of research" and of the need to incorporate both African-centred studies and White European, academic perspectives. He later outlined that "research conferences and publications on the history and language of Kemet [Egypt] remain dominated, beyond 90%, by those brought up and trained in European, not African societies and languages (which include Arabic)".^[237]

The Black Egyptian hypothesis includes a particular focus on links to Sub Saharan cultures and the questioning of the race of specific notable individuals from Dynastic times, including Tutankhamun^[238] the person represented in the Great Sphinx of Giza,^{[229][239][240]} and the Greek Ptolemaic queen Cleopatra.^{[241][242][243][244]} Advocates of the Black African model rely heavily on writings from Classical Greek historians, including Strabo, Diodorus Siculus, Ammianus Marcellinus, and Herodotus. Advocates claim that these "classical" authors referred to Egyptians as "Black with woolly hair".^{[note 2]} The Greek word used was "melanchroes", and the English language translation of this Greek word is disputed, being translated by many as "dark-skinned"^[249][250] and by many others as "black".^{[note 3][note 6]}

Other claims used to support the Black Hypothesis included anthropological measurements of Egyptian mummies, testing melanin levels in a small sample of mummies,^{[15]: 20, 37 [276]} language affinities between ancient Egyptian language and sub-saharan languages,^{[15]: 28, 39–41, 54–55 [277]} interpretations of the origin of the name Kmt, conventionally pronounced Kemet, used by the ancient Egyptians to describe themselves or their land (depending on points of view),^{[15]: 27, 38, 40} biblical traditions,^{[278][15]: 27–28} shared B blood group between Egyptians and West Africans,^[15]: 37 and interpretations of the depictions of the Egyptians in numerous paintings and statues.^[279]

The hypothesis also claimed cultural affiliations, such as circumcision,^[280] matriarchy, totemism, hair braiding, head binding,^[281] and kingship cults.^[282] Artifacts found at Qustul (near Abu Simbel – Modern Sudan) in 1960–64 were seen as showing that ancient Egypt and the A-Group culture of Nubia shared the same culture and were part of the greater Nile Valley sub-stratum,^{[283][284][285][286][287]} but more recent finds in Egypt indicate that the Qustul rulers probably adopted/emulated the symbols of Egyptian pharaohs.^{[288][289][290][291][292][293]}

Authors and critics state the hypothesis is primarily adopted by Afrocentrists.^{[294][295][296][297][298][299][300][301]} The current position of modern scholarship is that the Egyptian civilization was an indigenous Nile Valley development (see population history of Egypt),^{[223][224][53][225][302][227]} 

 

The Ancient Egyptian classification of ancient peoples (from left to right): a Libyan, a Nubian, an Asiatic, and an Egyptian. Drawing by an unknown artist after a mural of the tomb of Seti I; Copy by Heinrich Menu von Minutoli (1820). In terms of skin colour, the Libyan has the lightest complexion, followed by the Asiatic who is yellowish in appearance. The Egyptian is reddish-brown, while the Nubian is black.^[1] Each group is also marked with their own distinctive hairstyles and clothing.^[2] The representation of ethnic groups in Egyptian iconography has been a source of dispute among scholars.^[3][4]

https://en.wikipedia.org/wiki/Ancient_Egyptian_race_controversy#Black_Egyptian_hypothesis

https://en.wikipedia.org/wiki/Thrifty_gene_hypothesis

https://en.wikipedia.org/wiki/World_War_III

https://en.wikipedia.org/wiki/Nuclear_utilization_target_selection

https://en.wikipedia.org/wiki/Macdonald_triad

https://en.wikipedia.org/wiki/Macdonald_triad

 

https://en.wikipedia.org/wiki/Red_Queen_(Through_the_Looking-Glass)

 

 https://en.wikipedia.org/wiki/Mirror

 

https://en.wikipedia.org/wiki/Scrape

Flutter correction

Novel DSP processes have been developed that correct wow and flutter by tracking various spuriae on the tape or film which can be re-purposed as timing references. Several recent (2006) DVD releases have utilized a system developed by Plangent Processes that substantially reduces wow and flutter of very high rates to extremely low levels, with a substantial improvement in quality, and without adding distortion or extra cycles of sound. The software Capstan by Celemony analyzes the already digitalized musical material and uses varispeed playback to eliminate wow and flutter.

Scrape flutter

High-frequency flutter, above 100 Hz, can sometimes result from tape vibrating as it passes over a head (or other non-rotating element in the tape path), as a result of rapidly interacting stretching in the tape and stick-slip at the head. This is termed 'scrape flutter'. It adds a roughness to the sound that is not typical of wow & flutter, and damping devices or heavy rollers are sometimes employed on professional tape machines to reduce or prevent it. Scrape flutter measurement requires special techniques, often using a 10 kHz tone.

See also

• Audio quality measurement
• Noise measurement
• Headroom
• Rumble measurement
• ITU-R 468 noise weighting
• A-weighting
• Weighting filter
• Equal-loudness contour
• Fletcher–Munson curves
• Flutter (electronics and communication)
• Wow (recording)

References

Categories:

• Audio engineering
• Broadcast engineering
• Sound production technology
• Sound recording
• Sound

https://en.wikipedia.org/wiki/Wow_and_flutter_measurement#Flutter_correction

https://en.wikipedia.org/wiki/Incremental_search

https://en.wikipedia.org/wiki/List_of_radar_types

https://en.wikipedia.org/wiki/Dichotomic_search

https://en.wikipedia.org/wiki/Metasearch_engine

In microeconomics, search theory studies buyers or sellers who cannot instantly find a trading partner, and must therefore search for a partner prior to transacting.It involves determining the best approach to use when looking for a specific item or person in a sizable, uncharted environment.The goal of the theory is to determine the best search strategy, one that maximises the chance of finding the target while minimising search-related expenses.

Search theory clarifies how buyers and sellers choose when to acknowledge a coordinating offer for a transaction. Search theory also provides an explanation for why frictional unemployment happens as people look for jobs and corporations look for new employees.

Search theory has been used primarily to explain labor market inefficiencies, but also for all forms of "buyers" and "sellers", whether products, homes or even spouses/partners. It can be applied. The clearing price will be met quickly as supply and demand react freely. However, this does not happen in the real world. Search theory tries to explain how.Real-world transactions involve discrete quantities of goods and services, imperfect and expensive information, and possible physical or other barriers separating buyers and sellers. parties looking to conduct business, such as a potential employee and an employer, or a buyer and a seller of goods. Their search for one another is strained by this encounter. These restrictions can come in the form of geographical differences, differing expectations regarding price and specifications, and slow response and negotiation times from one of the parties.^[1]

Search theory has been applied in labor economics to analyze frictional unemployment resulting from job hunting by workers. In consumer theory, it has been applied to analyze purchasing decisions. From a worker's perspective, an acceptable job would be one that pays a high wage, one that offers desirable benefits, and/or one that offers pleasant and safe working conditions. From a consumer's perspective, a product worth purchasing would have sufficiently high quality and be offered at a sufficiently low price. In both cases, whether a given job or product is acceptable depends on the searcher's beliefs about the alternatives available in the market.

More precisely, search theory studies an individual's optimal strategy when choosing from a series of potential opportunities of random quality, under the assumption that delaying choice is costly. Search models illustrate how best to balance the cost of delay against the value of the option to try again. Mathematically, search models are optimal stopping problems.

Macroeconomists have extended search theory by studying general equilibrium models in which one or more types of searchers interact. These macroeconomic theories have been called 'matching theory', or 'search and matching theory.

https://en.wikipedia.org/wiki/Search_theory

In mathematics, the theory of optimal stopping^[1][2] or early stopping^[3] is concerned with the problem of choosing a time to take a particular action, in order to maximise an expected reward or minimise an expected cost. Optimal stopping problems can be found in areas of statistics, economics, and mathematical finance (related to the pricing of American options). A key example of an optimal stopping problem is the secretary problem. Optimal stopping problems can often be written in the form of a Bellman equation, and are therefore often solved using dynamic programming. 

https://en.wikipedia.org/wiki/Optimal_stopping 

https://en.wikipedia.org/wiki/body_retainer_stability_health_

https://en.wikipedia.org/wiki/shell_swap_cycle

https://en.wikipedia.org/wiki/rebodiment_life_extension_deception

https://en.wikipedia.org/wiki/optimal_trace_record_survivors_with_esteem_product

https://en.wikipedia.org/wiki/hostage_cl1_same_country_no_alter_odd_situations_camrad_language_no_rescue_passing_outcome_etc.

https://en.wikipedia.org/wiki/home-count-outcome-v-debarration-asian-liability-as-americans-no-don

https://en.wikipedia.org/wiki/fraud-vague-piety-feign-gay-life-illness-psychogenit-massive-world

 https://en.wikipedia.org/wiki/cover-job-as-civilian-contributionist-pay-schedule-interest-outcome-measure-license-valid-identity-real-shell-attachment-disorder-dependency-on-builder-no-kill-record-beg-for-kill-no-compliance-license-perpetuation-support-royalty-pleas-to-church-blaphemy-extended-menacation-relation-eurasian-varieties-all-inclusive-caucasians-etc.

https://en.wikipedia.org/wiki/crime-no-death

https://en.wikipedia.org/wiki/group-schemes

https://en.wikipedia.org/wiki/equity-perversation-attack-of-ss

https://en.wikipedia.org/wiki/recycling-of-worked-men-higher-ranking-infiltration-and-corruption-of-the-working-men

https://en.wikipedia.org/wiki/enslavement-of-men-by-races-women-wemels-kids-niggers-etc.

https://en.wikipedia.org/wiki/false-history-foundation-retainer-time-amensia-precedence-of-interest-psycho-scaling-outcome-estimate

https://en.wikipedia.org/wiki/no-endorsation-debarrment-confound-psycho-identification-america-europe-russia-roma-roman-romaninov

https://en.wikipedia.org/wiki/hostage-men-equity-honor-duke-prince-king-above-etc.

https://en.wikipedia.org/wiki/compulso-sequelas-etc.

https://en.wikipedia.org/wiki/education-language-scheme-usa-nac-dom

https://en.wikipedia.org/wiki/search-for-hostage-men-to-release-leave-alone-or-alternate-weight-by-don-or-search-to-release-with-no-re-clause-enslavement-their-or-here-find-surprise-fault-system

https://en.wikipedia.org/wiki/failed-system-flawed-foundation-fault-perp-theif-damage-unpaid

https://en.wikipedia.org/wiki/Optimal_stopping-account-ss-redactory-heroism-unpaid

https://en.wikipedia.org/wiki/ss-coupling-to-enemy-no-hostag

https://en.wikipedia.org/wiki/heav-trac-delug-au-pop-usa-etc.

https://en.wikipedia.org/wiki/shell-swap-educat-rebodiment-leg-usa-inter-etc.

https://en.wikipedia.org/wiki/btr-rank-agent-equal-men-fraud-death

https://en.wikipedia.org/wiki/Optimal_stoppin-false-death-extent-to-operate-license

https://en.wikipedia.org/wiki/Optimal_stopping-bye