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Topic Review
Younger Dryas
The Younger Dryas (around 12,900 to 11,700 years BP) was a return to glacial conditions after the Late Glacial Interstadial, which temporarily reversed the gradual climatic warming after the Last Glacial Maximum (LGM) started receding around 20,000 BP. It is named after an indicator genus, the alpine-tundra wildflower Dryas octopetala, as its leaves are occasionally abundant in late glacial, often minerogenic-rich sediments, such as the lake sediments of Scandinavia. Physical evidence of a sharp decline in temperature over most of the Northern Hemisphere has been discovered by geological research. This temperature change occurred at the end of what the earth sciences refer to as the Pleistocene epoch and immediately before the current, warmer Holocene epoch. In archaeology, this time frame coincides with the final stages of the Upper Paleolithic in many areas. The Younger Dryas was the most recent and longest of several interruptions to the gradual warming of the Earth's climate since the severe LGM, about 27,000 to 24,000 years BP. The change was relatively sudden, taking place in decades, and it resulted in a decline of temperatures in Greenland by 4 to 10°C (7.2 to 18°F) and advances of glaciers and drier conditions, over much of the temperate Northern Hemisphere. It is thought to have been caused by a decline in the strength of the Atlantic meridional overturning circulation, which transports warm water from the Equator towards the North Pole, in turn thought to have been caused by an influx of fresh, cold water from North America to the Atlantic. The Younger Dryas was a period of climatic change, but the effects were complex and variable. In the Southern Hemisphere and some areas of the Northern Hemisphere, such as southeastern North America, a slight warming occurred.
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  • 14 Oct 2022
Topic Review
Yana, India
Yana is a village located in forests of the Sirsi and Kumta Uttara Kannada district of Karnataka, India which is known for the unusual karst rock formations. It is located in the Sahyadri mountain range of the Western Ghats, about 60 kilometres (37 mi) from Karwar port, 39 kilometres (24 mi) from Sirsi, and 31 kilometres (19 mi) from Kumta. Yana is one of the wettest villages in the world. It is the cleanest village in Karnataka, and the second cleanest village in India . The two unique rock outcrops near the village are a tourist attraction and easily approachable by a small trek through 0.5 kilometres (0.31 mi) of thick forests from the nearest road head. Yana is famous for these two massive rock outcrops known as the Bhairaveshwara Shikhara and the Mohini Shikhara ("Shikhara" means "hill"). The huge rocks are composed of solid black, crystalline karst limestone. Bhairaveshwara Shikhara is 120 metres (390 ft) in height, while the Mohini Shikhara, which is smaller, is 90 metres (300 ft) in height. Yana is also well known as a pilgrimage centre because of the cave temple below the Bhairaveshwara Shikhara where a Swayambhu ("self manifested", or "that which is created by its own accord") linga has been formed. Water drips from the roof over the linga, adding to the sanctity of the place. During Shivaratri here, a car festival is held, along with other festivities. The place and its surrounding hillocks are also known for their evergreen scenic forests.
  • 440
  • 14 Oct 2022
Topic Review
Wolf Distribution
Wolf distribution is the species distribution of the wolf (Canis lupus). Originally, wolves occurred in Eurasia above the 12th parallel north and in North America above the 15th parallel north. However, deliberate human persecution has reduced the species' range to about one-third, because of livestock predation and fear of wolf attacks on humans. The species is now extirpated (made locally extinct) in much of Western Europe, Mexico, and the contiguous United States , and completely from the British Isles and the Japanese archipelago. In modern history, the gray wolf occurs mostly in wilderness and remote areas, particularly in Canada , Alaska, the Northern United States, Europe and Asia from about the 75th parallel north to the 12th parallel north. Wolf population declines have been arrested since the 1970s, and have fostered recolonization and reintroduction in parts of its former range, due to legal protection, changes in land-use and rural human population shifts to cities. Competition with humans for livestock and game species, concerns over the danger posed by wolves to people, and habitat fragmentation pose a continued threat to the species. Despite these threats, because of the gray wolf's relatively widespread range and stable population, it is classified as Least Concern on the IUCN Red List. In Africa the population of wolves is limited to the northern regions with the African golden wolf (Canis lupaster) north of the Sahara and the Ethiopian wolf (Canis simensis) in Ethiopia.
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  • 25 Oct 2022
Topic Review
WISDOM Project
The WISDOM Project is a bilateral research project between Germany and Vietnam, focusing on the creation of a Water related Information System for the Mekong Delta. Initiated by the Vietnamese and the German Government it was started in the year 2007, and is planned to continue until the year 2013. Water-related Information System for the sustainable Development of the Mekong Delta in Vietnam
  • 348
  • 24 Nov 2022
Topic Review
Western European Colonialism and Colonization
File:SierraLeoneHofstra3.1.tiff European colonialism and colonization was the policy or practice of acquiring full or partial political control over other societies and territories, creating a colony, occupying it with settlers, and exploiting it economically. Research suggests, the current conditions of postcolonial countries have roots in colonial actions and policies. For example, colonial policies, such as the type of rule implemented, the nature of investments, and identity of the colonizers, are cited as impacting postcolonial states. Examination of the state-building process, economic development, and cultural norms and mores shows the direct and indirect consequences of colonialism on the postcolonial states.
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  • 04 Nov 2022
Topic Review
Western Caribbean Zone
The Western Caribbean Zone is a region consisting of the Caribbean coasts of Central America, from Yucatán in Mexico to northern Colombia, and also the islands west of Jamaica. The zone emerged in the late sixteenth century as the Spanish failed to completely conquer many sections of the coast, and northern European powers supported opposition to Spain, sometimes through alliances with local powers. Unsubdued indigenous inhabitants of the region included some Maya polities, and other chiefdoms and egalitarian societies, especially in Belize, eastern Honduras, Nicaragua, and Costa Rica. In addition, the region was the refuge of several groups of runaway slaves, who formed independent settlements or intermixed with the indigenous societies. The combination of unsubdued indigenous people, outlaws (pirates in this case), and an absence of outside control made it similar in some aspects to the American West or the Wild West, as the western half of North America is often called. Its long engagement with the English-speaking Caribbean made it an ideal conduit for trade from both the English colonies of the Caribbean, especially Jamaica, but also North America, which had been trading in the zone since the eighteenth century at least. The relatively low population and strategic location attracted United States -based transportation companies to promote infrastructure projects from railroads to the Panama Canal in the zone, and conjointly with that to introduce large-scale fruit production toward the end of the nineteenth century, often bringing in labor from the English-speaking Caribbean to assist. Unique elements of the region, relative to the population of Central America in general, is the high percentage of people of whole or partial African descent, and its cultural connections to English and the English-speaking Caribbean through language and religion.
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  • 18 Oct 2022
Topic Review
Vilabouly Complex, Laos
The Vilabouly Complex is an archaeological site that is located in the Savannakhet Province in Laos which holds copper smelting and copper mining during the Iron Age. The Vilabouly Complex is significant since it puts archaeologists in a predicament of when did the origin of bronze metallurgy begin in Southeast Asia. It was estimated that the site was around 400BC - AD 500 as well as 1000 - 400BC reaching both the Iron Age and Bronze Age of Southeast Asia. The site contained a lead signature that followed copper, bronze alloys, and bronze which signifies a massive source of material that can benefit metallurgy in the region. By this, the Vilabouly Complex will hold all the power of the region since it has all the resources to advance their technology during the Bronze and Iron Ages. The Vilabouly Complex and the region contained such mining sites such as Dragon Field, Peun Balo, Tengkham South D, Khanong A2, and the Malachite Cave. These sites all refer to the Iron Age but Peun Balo revealed mining in the Bronze Age continuing the predicament for Archaeologists. Research like this is vital for the Vilabouly Complex to find and understand the exact date to when the people of Southeast Asia are trading metals, and sharing mining techniques. There are also other sites in region such as the Prachan Valley that shared a lot of similarities to that of the Vilabouly Complex revealing continuities for the Southeast Asian people.
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  • 01 Nov 2022
Topic Review
Verneuil Process
The Verneuil process, also called flame fusion, was the first commercially successful method of manufacturing synthetic gemstones, developed in the late 1800s by the French chemist Auguste Verneuil. It is primarily used to produce the ruby, sapphire and padparadscha varieties of corundum, as well as the diamond simulants rutile and strontium titanate. The principle of the process involves melting a finely powdered substance using an oxyhydrogen flame, and crystallising the melted droplets into a boule. The process is considered to be the founding step of modern industrial crystal growth technology, and remains in wide use to this day.
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  • 18 Oct 2022
Topic Review
Varangian Guard
The Varangian Guard (Greek: Τάγμα τῶν Βαράγγων, Tágma tōn Varángōn) was an elite unit of the Byzantine Army, from the 10th to the 14th centuries, whose members served as personal bodyguards to the Byzantine Emperors. They are known for being primarily composed of Germanic peoples, specifically Norsemen from modern day Sweden (the Guard was formed approximately 200 years into the Viking Age) and Anglo-Saxons (after the Norman Conquest of England created an Anglo-Saxon diaspora, part of which found employment in Constantinople). The Rus' provided the earliest members of the Varangian Guard. They were in Byzantine service from as early as 874. The Guard was first formally constituted under Emperor Basil II in 988, following the Christianization of Kievan Rus' by Vladimir I of Kiev. Vladimir, who had recently usurped power in Kiev with an army of Varangian warriors, sent 6,000 men to Basil as part of a military assistance agreement. Basil's distrust of the native Byzantine guardsmen, whose loyalties often shifted, with fatal consequences, as well as the proven loyalty of the Varangians, many of whom had previously served in Byzantium, led the Emperor to employ them as his personal guardsmen. Immigrants from Sweden, Denmark , Norway and Iceland kept a predominantly Norse cast to the organization until the late 11th century. According to the late Swedish historian Alf Henrikson in his book Svensk Historia (History of Sweden), the Scandinavian Varangian guardsmen were recognized by long hair, a red ruby set in the left ear and ornamented dragons sewn on their chainmail shirts. In these years, Scandinavian men left to enlist in the Byzantine Varangian Guard in such numbers that a medieval Swedish law, Västergötlagen, from Västergötland declared no one could inherit while staying in "Greece"—the then Scandinavian term for the Byzantine Empire—to stop the emigration, especially as two other European courts simultaneously also recruited Scandinavians: Kievan Rus' c. 980–1060 and London 1018–1066 (the Þingalið). Composed primarily of Norsemen and Rus for the first 100 years, the Guard began to see increased numbers of Anglo-Saxons after the Norman conquest of England. By the time of the Emperor Alexios Komnenos in the late 11th century, the Varangian Guard was largely recruited from Anglo-Saxons and "others who had suffered at the hands of the Vikings and their cousins the Normans". The Anglo-Saxons and other Germanic peoples shared with the Vikings a tradition of faithful (to death if necessary) oath-bound service, and the Norman invasion of England resulted in many fighting men who had lost their lands and former masters and were looking for positions elsewhere. The Varangian Guard not only provided security for the Byzantine emperors, but also participated in many wars, often playing a decisive role, since they were usually deployed at critical moments of a battle. By the late 13th century, Varangians were mostly ethnically assimilated by the Byzantine Greeks, though the Guard remained in existence until at least mid-14th century. In 1400, there were still some people identifying themselves as "Varangians" in Constantinople.
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  • 04 Nov 2022
Topic Review
Upper Mantle (Earth)
The upper mantle of the Earth begins just beneath the crust about 35 km (22 mi) and ends at the top of the lower mantle at 670 km (420 mi). Temperatures range from approximately 200 °C (392 °F) at the upper boundary with the crust to approximately 900 °C (1,650 °F) at the boundary with the lower mantle. Upper mantle material which has come up onto the surface is made up of about 55% olivine, 35% pyroxene and 5 to 10% of calcium oxide and aluminum oxide minerals such as plagioclase, spinel or garnet, depending upon depth.
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  • 29 Sep 2022
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