Do the Mountains Grow?

In 1850 the height of Mount Everest ,the tallest peak of the world was surveyed and estimated as 29,002 feet.In a study conducted after a century ,the height was found to be 29,028.Height increased by 26 feet.In the studies involved mountains grow slightly every year .The height of the mountains increases because of some geological process taking place in the depth leading totheir slow and spasmodic uplift .These include folding of rock layers .Uplift of those layers often accompanied faulting or dislocation of rock layers .The term orogeny collectively denotes all process leading to formation of mountains

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Did the Earth always look the same?

Look at the map of the world .Examine the outlines of continets of South America and Africa.Aren't the jutting portions of South America suiting the western portion of Africa like a jigsaw puzzle?Can these two be joined?About 90 years ago a German scientist called Alfred Wegner proved that South America and Africa were once joined together .Wegner knew that there is similarity between rock strata and plant fossils of the continents of South America and Africa.He came to the conclusion that at some remote time,these two continents had been connected ,also on the basis of several other evidences he noted.He propounted the 'Continental Drift Theory'.According to this theory ,it was surmised that all the present continents had been united to a single land mass he named 'Pangaea',surrounded by"Panthalassa'an ancestral primitive ocean.Later this single continent disintegrated and drifted into different continents as we see them today.

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Can Earthquake be predicted?

Earthquakes are terrible.It can devastate large areas and takes lives of millions .The earthquake that took in Equador in 1906 had the power of 300 hydrogen bomb.That which happened in China in 1976 had the power of 1000 hydrogen bombs.In this quake that occurred in Tang Shan 3 lakh people were perished.

The crust of the earth when subjected to forces breaks along fractures resulting in earthquakes .When the waves originating from the sight of the fracturing move upward and reach the surface ,the earth seams to shake,bringing about large scale destruction.

Man had attempted to study earthquakes from ancient times,1500 years ago a Chinese mathematician Chang Heng made a device to detect earthquakes.made of pendulum that could respond to the slightest movement of earth ,fixed to a huge 2m diameter vessel,we don't know how efficient this device had been.



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Are the deserts expanding?

More than one fifth of the area of India is occupied by Thar Desert,Africa by Sahara Desert, China by Gobi  desert,South America By Atacama desert.The arid and semi arid lands constitute about two fifth of India where an estimated 200 million people are living.Deserts arid and semiarid regions of the world receive an average of less than 350 millimeter rain every year .These cover about 43 percent of earth's  land

surface.
 About 4500 years ago,the Harappan civilization flourished in regions now occupied by Thar desert.Rhinos and Elephants roamed in the forests that once grew there .large scale deforestation and climatic changes gradually converted the region into a desert. The Rajasthan desert is one of the  most densely populated deserts of  the world.The density of population is 48 persons per square kilometer. Rapid  increase in live stock population and increased cultivation  resulting in ploughing more  and more increased vulnerability of fertile soil if any  left to soil erosion

The deserts of the world show signs of expansion with time . Sahara desert is spreading southward as much as 50 km per year in some places . It has engulfed about 6500,000 square kilometers  of arable land during the last century.The situation is not different in South America ,West Asia,China and other places where desert occur.Many of the regions now occupied by deserts were once fertile.For about six centuries ,North Africa was one of the principal granaries of the ancient Roman empire.The sand dunes of Sahara covers the ruins of great cities once flourished there.