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Wednesday, March 24, 2010

geography short notes -8

PLAGIOCLASE



it is very important series of tectosilicate minerals within the fields par family. rather than referring to a particular mineral with a specific chemical composition, plagioclase is a solid solution series, more properly known as plagioclase feldspar series from greek word "oblique fractor" in reference to its two cleverage angles. the series range from arbite to anorthite endmembers where sodium & calcium atoms can substitue for each other in the mineral crystal lattice structure. plagioclase is a hand samples is often by its polysynthetic twinning or 'record-froove' effect. plagioclase is major constituent mineral in earth's crust. & is consequently an important diagnostic tool in petrology for identifying composition, origin & evolution of igneous rocks.

PLAGIOCLASE MINERALS & THEIR COMPOSITIONS


NAME = %NaAlSi3O8(%Ab) = % CaAl2Si2O8(%An)

- albite = 100-90 = 0-10

- oligoclase = 90-70 = 10-30

- andesine = 70-50 = 30-50

- labradorite = 50-30 = 50-70

- bytowrite = 30-10 = 70-90

- anorthite = 10-0 = 90-100

ALBITE


is named from latin albus, in reference to its unusally pure white color. it is relatively common & important rock-making mineral associated with the more acid rock types & in pegmatite dikes, often with rare minerals like bery & tourmaline.

ANORTHITE


was named by the Rose in 1823 from the greek meaning oblique, referring to its triclinic crystallization. anorthite is characteristic of the mafic igneous rocks such as gabbro & basalt.

OLIGOCLASE


is common in granite, syenite, diotire & gneiss. it is frequent associate of orthoclase. the name oligoclase is derived from the greek for little & fracture in reference to the fact that its clevage angle differs significantly from 90 degree. sunstone is mainly oligoclase with flakes of hematite.

ANDESINE


is a characteristcs mineral of rocks such as diorite which contain a moderate amount of silica related volcanics such as andesite.

LABRADORITE


is the feldspar of the more basic rock types such as divrite, gabbro, andesite. basalt is usually associated with one of the pyroxenes. labradorite frequently shows an iridescent disply of colors to light refracting within the lamellae of the display.

BYTOWRITE


named after the former name of Ottawa, Canada. it is rare mineral occasionally found in more basic rocks.



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Polynesia!

POLYNESIA

Polynesia is generally defined as the islands within the polynesian triangle. the term "polynesia", meaning many islands, was first used by charles de brosses in 1756, & originally islands of the Pacific. jules dumont d'uvrille in 1831 a lecturer to the geographical society of paris proposed a restriction on its use. geographically , & oversimply, polynesia may be described as triangle with its corners at hawaii, aotearoa (new zealand) & rapu nui (easter island). the other main island groups located within the polynesian triangle are samoa, tonga, the various island chains that form the cook islands & french polynesia. nuie is a rare solitary island state near the centre of polynesia. polynesian island groups outside this great triangle include tuvalu & french territory of wallis & futuna. rotuma in the northern fijian islands & some of the lau group to fiji's southeast have strong polynesian character too. in essance, it is an anthropological term referring to one of the three parts of Oceania whose pre-colonial generally belongs to one ethno-cultural family as a result of centuries of maritime migrations.




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PRODUCER'S OF DIFFERENT CROPS IN WORLD

  • The Largest producer of groundnut in World =India
  • The Largest producer of Tobacco in World = China
  • The Largest Quantity of Barley is produced in World = Russia
  • The Largest producer of Long Staple Cotton in World = USA
  • The Largest Cattle production in World = India
  • The Largest producer of Butter & Ghee in World = India
  • The Largest producer of Rice in World = India & USA
  • The Largest producer of Fish in World = China
  • The Largest producer of Mutton in World = New Zealand & Australia.
  • The Largest producer of Mercury in World = Spain
  • The Largest producer of Rock Phosphate in World = USA & Russia.
  • The Leading producer of Uranium in World = Canada
  • The Leading producer of Automobiles in World = USA
  • The Leading producer of Cement in World = USA
  • The Country that Manufactures due Maximum number of Locomotives in World = USA
  • The Country known for Locomotive = Philadelphia
  • The Country famous for Petroleum = Baku
  • The Country famous for Wollen textiles in World = Leeds.
  • The Country known as Sugar Bowl in World = Cuba.
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Tiger reserves in India

Hai all the members,
by mistake, 5 of the states of below Tiger reserves were given wrong. I have given below the corrected information in BOLD letters. please verify. thank you,
Thank you for the right information and founding out the mistake chanda sir.

1.Bandipur National Park (1973-74) - Karnataka
2.Jim Corbett National Park (1973-74) - Uttar Pradesh
3.Kanha National Park (1973-74) - Madhya Pradesh
4.Manas National Park (1973-74) - Assam
5.Melghat Wildlife Sanctuary (1973-74) - Maharashtra
6.Palamau National Park (1973-74) - Jharkhand
7.Ranthambore National Park (1973-74) - Rajasthan
8.Simlipal National Park (1973-74) - Orissa
9.Sunderbans National Park (1973-74) - West Bengal
10.Periyar National Park (1978-79) - Kerala
11.Sariska National Park (1978-79) - Rajasthan
12.Buxa National Park (1982-83) - West Bengal
13.Indravati National Park (1982-83) - Chattisgarh
14.Nagarjunsagar National Park (1982-83) - Andhra Pradesh
15.Namdapha National Park (1982-83) - Arunachal Pradesh
16.Dudhwa National Park (1987-88) - Uttar Pradesh
17.Kalakad-Mundanthurai Tiger Reserve (1988-89) - Tamil Nadu
18.Valmiki National Park (1989-90) - Bihar
19.Pench National Park (1992-93) - Madhya Pradesh
20.Tadoba-Andhari Tiger Reserve (1993-94) - Maharashtra
21.Bandhavgarh National Park (1993-94) - Madhya Pradesh
22.Panna National Park (1994-95) - Madhya Pradesh
23.Dampha Tiger Reserve (1994-95) - Mizoram
24.Bhadra National Park (1998-99) - Karnataka
25.Pench National Park (1998-99) - Maharashtra
26.Pakhui-Nameri Tiger Reserve (1999-2000) - Assam and Arunachal
pradesh

27.Bori, Satpura & Pachmarhi Wildlife Sanctuaries (1999-2000) - Madya
Prades

28.Katerniaghat Wildlife Sanctuary Extension (1999-2000) - Uttar Pradesh
29.Nagarhole National Park Extension (1999-2000) - Karnataka

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RIVER REJUVENATION

river is to be rejuvenated when the base level that is flowing down to, is lowered. this can happen by uplift of land, or by a sea or lake that it is flowing into becoming lower. that makes the river suddenly start eroding its bed vertically faster as it gains gravitational potential energy. that causes effect such as meanders cut down as gorges, steps where river suddenly starts flowing faster, & terraces derived from old floodplains. Rejuvenation terrains usually have complex landscape, because remnants of older landforms are locally preserved. parts of flodd pains may be preserved as terraces along the downcutting stream channels. Meandering streams often become entrenched , so a product of older river system is found with step, very pronounced "V" shaped valley. Rejuvenation result from causes which are dynamic, eustatic / static in nature.

I. DYNAMIC : dynamic rejuvenation may be caused by the epeirogenic uplift of a land mass. there movements are either associated with neighbouring orogenic movements.

II. EUSTATIC : this rejuvenation results from the causes which bring worldwide decrease in sea level, & 2 types of such rejuvenation are recognized.

DIASTROPHIC EUSTATISM : it is the change in sea level due to variation incapacity of ocean basins.

GLACIO-EUSTATISM : is the change in sea level due to withdrawal of water into the oceans occupying the accumulation of successive ice sheet.

CHANGES OF STATIC :
- decrease in land
- increase in runoff because of rainfall
- increase in stream volume through acquisition of new drainage by stream diversion
 
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SCORIA

it is a textual term for macrovesicular volcanic rocks ejecta. it is commonly , but not exclusively basaltic in composition. scoria is light as a result of numerous macroscopic ellipsoidal vesicles but most scoria has a specific gravity than 1 & sinks in water. the vasicularity results from the exsolution of magnetic volatiles prior to chilling. scoria differs from purnice in having layer vesicles & thicker vesicles walls, & hence is typically darker in color. it is generally dark brown, dark red, dark black. the word comes from greek skoria means "rust". as raising magma encounters lower pressures, dissolved gasses are able to exsolve & form vesicles. some of the vesicules are trapped when the magma chills & solidifies. vesicules are usually small, spheroidal & donot impringe upon one another, it is formed from a thin layer of froth occuring on some basaltic lava flows due to the bursting of vasicle walls. the thin glass threads are the inter-section of burst vehicles. this is the lightest rock on earth with its specific gravity less than 0.3.
 
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SILLIMANITE

it is also called as Bucholzite . is ia an alumino-silicate mineral with chemical formula Al2SiO2. it is named after American Achemist Brjamin silliman (1779-1864). it is one of the three alumino-silicate : polymorphhs, kyanite & andalusite. a common variety of sillimanite is known as fibrolite, so named because the mineral appears like a bunch of fibres twisted together when viewed under this section or even naked eye. both the fibrous & traditional forms of silicate are common in metamorphosed sedimentary rocks . it is an index mineral indicating a high degree of metamorphtism. sillimanite has been found in brandywine springs, new castle country, delaware, usa. it is also known as rock creek shear zone with the piedmont physiographic provience.

CHARACTERISTIC FEATURES :

CRYSTALLOGRAPHIC = orthorhombic
COLOURS = white, brown, green
LUSTRE = silky if in fibrous form, else vitreous
HARDNESS = 7.5
REFRACTIVE INDEX = 1.641-1.648
CLEAVAGE = 1
PLEOCHROSIM = colourless to pale brown to yellow
TYPE LOCALITY = wtava, susica, czech republic
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  • Do rivers always flow from the north to the south?
    While some oblivious people think that rivers always flow from the north to the south (a term some even call downhill!) but rivers always flow with gravity (unless modified by humans). There are countless examples of rivers that flow from the south to the north (in both hemispheres), such as the Ob in Russia and the Mackenzie in Canada.
    An interesting analogy was brough up in the Geography Forum - would you fly to Seattle, rent a car, and coast all the way to Los Angeles? Just because south is at the bottom of the map, doesn't mean it's lower in elevation.
  • How many active volcanoes are in the world?
    There are approximately 1,500 active volcanoes worldwide.
    A volcano is considered active if it has erupted in the last 10,000 years. Over 75% of the world's volcanoes and most active volcanoes are located in the Pacific Ring of Fire.
  • What are the seven seas?
    Although seamen of long ago are popularly known to have stated "I've sailed the seven seas," there really wasn't a good definition of those seas. However, today
  • How many tectonic plates are on earth?
    There are dozens of tectonic plates on earth but only about one seven huge plates. The largest include the African Plate, Antarctic Plate, Eurasian Plate, Indo-Australian Plate, North American Plate, Pacific Plate, South American Plate
  • How do you convert snow into rainfall amounts?
    Since precipitation is generally measured in inches of liquid water and not in snowfall amounts, snow is usually converted into inches of water by dividing by 10. Thus, ten inches of snow is equivalent to one inch of rain.
    Light and loose snow takes more than 10 inches to make an inch of water but dense and slushy snow takes less.
  • What effect does the Coriolis force have upon my bathtub?
    It's granted that the Coriolis effect has an affect on the circulation of air and water on the planet but many people also think that the force has an effect on sinks, wash basins, toilets, bathtubs and other tiny bodies of water.
    Unfortunately, small bodies of water are not affected by the Coriolis effect or bearing on whether sinks and toilets drain in one direction in the Northern Hemisphere and another direction in the Southern Hemisphere
  • How often does a 100-year flood occur?
    Large floods are often given designations as a "one-hundred-year flood" but a 100-year flood does not mean that such a flood occurs once every 100 years; instead it means that there is a one in one-hundred (or 1%) chance of such a flood occurring in a given year.
    Two 100-year floods could occur a year apart or even a month apart -- it all depends on how much rain is falling or how quickly the snow melts. A "20-year flood" has a one in twenty (or 5%) chance of occurring in a particular year so it would be a less destructive flood than a 100-year flood while a "500-year flood" has a one in 500 (0.2%) chance of occurring so it would be much more catastrophic than a 100-year flood.


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