Geography Compendium

Nacre
Nacre, also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer. It is strong, resilient, and iridescent.Nacre is found in certain ancient lineages of bivalves, gastropods and cephalopods. However, the inner-shell layer in the great majority of shelled mollusks is porcellaneous and non-nacreous, frequently resulting in a non-iridescent shine like that of a porcelain plate or, in some species, presenting non-nacreous iridescent effects such as ‘flame structure’ (e.g. conch pearl).Pearls and the inside layer of pearl oyster shells and freshwater pearl mussel shells are made of nacre. Many other families of mollusks also have an inner shell layer which is nacreous, including marine gastropods such as the Haliotidae, the Trochidae and the Turbinidae.

Nebular Hypothesis
Nebular hypothesis is the most widely accepted model explaining the formation and evolution of the Solar System. It was first proposed in 1734 by Emanuel Swedenborg. Originally applied only to our own Solar System, this method of planetary system formation is now thought to be at work throughout the universe. The widely accepted modern variant of the nebular hypothesis is Solar Nebular Disk Model (SNDM) or simply Solar Nebular Model.

According to SNDM stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC). They are gravitationally unstable, and matter coalesces to smaller denser clumps within, which then proceed to collapse and form stars. Star formation is a complex process, which always produces a gaseous protoplanetary disk around the young star. This may give birth to planets in certain circumstances, which are not well known. Thus the formation of planetary systems is thought to be a natural result of star formation. A sun-like star usually takes around 100 million years to form.

New Moore Island
South Talpatti Island as it is known in Bangladesh or New Moore Island or Purbasha in India is a small uninhabited offshore island that emerged in the Bay of Bengal in the aftermath of the Bhola cyclone in 1970. There is no permanent settlement or any other station located on the island. It is situated only two kilometers from the mouth of the Hariabhanga river.

Ocean Currents
An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon the water, such as the Earth’s rotation, wind, temperature, salinity differences and tides caused by the gravitational pull of the Moon and the Sun. Depth contours, shoreline configurations and interaction with other currents influence a current’s direction and strength.

Ocean currents can flow for thousands of kilometers, and together they create the great flow of the global conveyor belt which plays a dominant part in determining the climate of many of the Earth’s regions. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Another example is the Hawaiian Islands, where the climate is cooler (sub-tropical) than the tropical latitudes in which they are located, because of the effect of the California Current.

National Diet of Japan
The National Diet of Japan is Japan’s bicameral legislature. It is composed of a lower house, called the House of Representatives, and an upper house, called the House of Councillors. Both houses of the Diet are directly elected under a parallel voting system. In addition to passing laws, the Diet is formally responsible for selecting the Prime Minister. The Diet was first convened as the Imperial Diet in 1889 as a result of adopting the Meiji constitution. The Diet took its current form in 1947 upon the adoption of the postwar constitution and is considered by the Constitution to be the highest organ of state power. The National Diet Building is located in Nagatacho, Chiyoda, Tokyo.

Cortes Generales
The Cortes Generales is the legislature of Spain. It is a bicameral parliament, composed of the Congress of Deputies (the lower house) and the Senate (the upper house). The Cortes has power to enact any law and to amend the constitution. Moreover, the lower house has the power to appoint and dismiss the Prime Minister. However, because Spain is a European Union (EU) member state, it shares its legislative authority with the council and parliament of the EU.

People’s Daily of China
The People’s Daily a daily newspaper, is the organ of the Central Committee of the Communist Party of China (CCP), published worldwide with a circulation of 3 to 4 million. In addition to its main Chinese-language edition, it has editions in English, Japanese, French, Spanish, Russian, and Arabic. As the CCP’s mouthpiece, the newspaper generally provides direct information on the policies and viewpoints of the Party.

Quartzite
Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe2O3). Other colors are commonly due to impurities of minor amounts of other minerals.

Gneiss
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.

Schists
The schists form a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is produced. By definition, schist contains more than 50% platy and elongated minerals, often finely interleaved with quartz and feldspar.

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