EARTH

How Old Is the Earth?

In the very beginning of earth' s history, this planet was a giant, red hot, roiling, boiling sea of molten rock - a magma ocean.

The heat had been generated by the repeated high speed collisions of much smaller bodies of space rocks that continually clumped

Together as they collided to form this planet. As the collisions tapered off the earth began to cool, forming a thin crust on its surface.

As the cooling continued, water vapor began to escape and condense in the earth's early atmosphere. Clouds formed and storms raged, raining

more and more water down on the primitive earth, cooling the surface further until it was flooded with water, forming the seas.

It is theorized that the true age of the earth is about 4.6 billion years old, formed at about the same time as the rest of our solar system.

The oldest rocks geologists have been able to find are 3.9 billion years old. Using radiometric dating methods to determine the age of rocks means

Scientists have to rely on when the rock was initially formed (as in - when its internal minerals first cooled). In the infancy of our home planet

The entire earth was molten (melted) rock - a magma ocean.

Since we can only measure as far back in time as we had solid rock on this planet, we are limited in how we can measure the real age of the earth. Due to the forces of plate tectonics, our planet is also a very dynamic one; new mountains forming, old ones wearing down, volcanoes melting and reshaping new crust. The continual changing and reshaping of the earth's surface that involves the melting down and reconstructing of old rock has pretty much eliminated most of the original rocks that came with earth when it was newly formed. So the age is a theoretical age.

When Did Life on Earth Begin?



Scientists are still trying to unravel one of the greatest mysteries of earth: When did "life" first appear and how did it happen? It is estimated that the first life forms on earth were primitive, one-celled creatures that appeared about 3 billion years ago. That's pretty much all there was for about the next two billion years. Then suddenly those single celled organisms began to evolve into multicellular organisms. Then an unprecedented profusion of life in incredibly complex forms began to fill the oceans. Some crawled from the seas and took residence on land, perhaps to escape predators in the ocean. A cascading chain of new and increasingly differentiated forms of life appeared all over the planet, only to be virtually annihilated by an unexplained mass extinction. It would be the first of several mass extinctions in Earth's history

Where do Gemstones come from?

Scientists have been looking increasingly to space to explain these mass extinctions that have been happening almost like clockwork since the beginning of "living" time. Perhaps we've been getting periodically belted by more space rocks (ie. asteroids), or the collision of neutron stars happening too close for comfort? Each time a mass extinction occurred, life found a way to come back from the brink. Life has tenaciously clung to this small blue planet for the last three billion years. Scientists are finding new cues as to how life first began on earth in some really interesting places - the deep ocean.

Checking the Fossil Record

Scientists have studied rocks using radiometric dating methods to determine the age of earth. Another really cool thing they've found in rocks that tells us more about the story of earth's past are the remains of living creatures that have been embedded in the rocks for all time. We call these fossils. It has been the careful study of earth's fossil record that has revealed the exciting picture about the kinds of creatures that once roamed this planet. Fossilized skeletons of enormous creatures with huge claws and teeth, ancient ancestors of modern day species (such as sharks) that have remained virtually unchanged for millions of years, and prehistoric jungles lush with plant life, all point to a profusion of life and a variety of species that continues to populate the earth, even in the face of periodic mass extinctions.

By studying the fossil record scientists have determined that the earth has experienced very different climates in the past. In fact, general climactic conditions, as well as existing species, are used to define distinct geologic time periods in earth's history. For example, periodic warming of the earth - during the Jurassic and Cretaceous periods - created a profusion of plant and animal life that left behind generous organic materials from their decay. These layers of organic material built up over millions of years undisturbed. They were eventually covered by younger, overlying sediment and compressed, giving us fossil fuels such as coal, petroleum and natural gas.

Alternately, the earth's climate has also experienced periods of extremely cold weather for such prolonged periods that much of the surface was covered in thick sheets of ice. These periods of geologic time are called ice ages and the earth has had several in its history. Entire species of warmer-climate species died out during these time periods, giving rise to entirely new species of living things which could tolerate and survive in the extremely cold climate. Believe it or not, humans were around during the last ice age - the Holocene (about 11,500 years ago) - and we managed to survive. Creatures like the Woolly Mammoth - a distant relative of modern-day elephants - did not.

Read about a really exciting recent find of a perfectly-preserved, frozen Woolly Mammoth! This was a particularly exciting find because it wasn't a fossil that scientists found, but actual tissue, which still has its DNA record intact.

Also, read more about the Ice Man - another frozen tissue sample of a human being who was frozen into the high mountains of France. He was just recently discovered as thousands of years of ice pack have finally melted from around his body..........to be contiounce




                       

Indian History

Beauty of Delhi

                                                                                                                                                                             

Parliament of India Delhi 

President House Delhi

History of India . An overview : The people of India have had a continuous civilization since 2500 B.C., when the inhabitants of the Indus River valley developed an urban culture based on commerce and sustained by agricultural trade. This civilization declined around 1500 B.C., probably due to ecological changes.


During the second millennium B.C., pastoral, Aryan-speaking tribes migrated from the northwest into the subcontinent. As they settled in the middle Ganges River valley, they adapted to antecedent cultures.


The political map of ancient and medieval India was made up of myriad kingdoms with fluctuating boundaries. In the 4th and 5th centuries A.D., northern India was unified under the Gupta Dynasty. During this period, known as India's Golden Age, Hindu culture and political administration reached new heights.


Islam spread across the Indian subcontinent over a period of 500 years. In the 10th and 11th centuries, Turks and Afghans invaded India and established sultanates in Delhi. In the early 16th century, descendants of Genghis Khan swept across the Khyber Pass and established the Mughal (Mogul) Dynasty, which lasted for 200 years. From the 11th to the 15th centuries, southern India was dominated by Hindu Chola and Vijayanagar Dynasties. During this time, the two systems--the prevailing Hindu and Muslim--mingled, leaving lasting cultural influences on each other.


The first British outpost in South Asia was established in 1619 at Surat on the northwestern coast. Later in the century, the East India Company opened permanent trading stations at Madras, Bombay, and Calcutta, each under the protection of native rulers.
The British expanded their influence from these footholds until, by the 1850s, they controlled most of present-day India, Pakistan, and Bangladesh. In 1857, a rebellion in north India led by mutinous Indian soldiers caused the British Parliament to transfer all political power from the East India Company to the Crown. Great Britain began administering most of India directly while controlling the rest through treaties with local rulers.

In the late 1800s, the first steps were taken toward self-government in British India with the appointment of Indian councilors to advise the British viceroy and the establishment of provincial councils with Indian members; the British subsequently widened participation in legislative councils. Beginning in 1920, Indian leader Mohandas K. Gandhi transformed the Indian National Congress political party into a mass movement to campaign against British colonial rule. The party used both parliamentary and nonviolent resistance and non-cooperation to achieve independence.

 On August 15, 1947, India became a dominion within the Commonwealth, with Jawaharlal Nehru as Prime Minister. Enmity between Hindus and Muslims led the British to partition British India, creating East and West Pakistan, where there were Muslim majorities. India became a republic within the Commonwealth after promulgating its constitution on January 26, 1950.

After independence, the Congress Party, the party of Mahatma Gandhi and Jawaharlal Nehru, ruled India under the influence first of Nehru and then his daughter and grandson, with the exception of two brief periods in the 1970s and 1980s.

Prime Minister Nehru governed India until his death in 1964. He was succeeded by Lal Bahadur Shastri, who also died in office. In 1966, power passed to Nehru's daughter, Indira Gandhi, Prime Minister from 1966 to 1977. In 1975, beset with deepening political and economic problems, Mrs. Gandhi declared a state of emergency and suspended many civil liberties. Seeking a mandate at the polls for her policies, she called for elections in 1977, only to be defeated by Moraji Desai, who headed the Janata Party, an amalgam of five opposition parties.


In 1979, Desai's Government crumbled. Charan Singh formed an interim government, which was followed by Mrs. Gandhi's return to power in January 1980. On October 31, 1984, Mrs. Gandhi was assassinated, and her son, Rajiv, was chosen by the Congress (I)--for "Indira"--Party to take her place. His government was brought down in 1989 by allegations of corruption and was followed by V.P. Singh and then Chandra Shekhar.

In the 1989 elections, although Rajiv Gandhi and Congress won more seats in the 1989 elections than any other single party, he was unable to form a government with a clear majority. The Janata Dal, a union of opposition parties, was able to form a government with the help of the Hindu-nationalist Bharatiya Janata Party (BJP) on the right and the communists on the left. This loose coalition collapsed in November 1990, and the government was controlled for a short period by a breakaway Janata Dal group supported by Congress (I), with Chandra Shekhar as Prime Minister. That alliance also collapsed, resulting in national elections in June 1991.

On May 27, 1991, while campaigning in Tamil Nadu on behalf of Congress (I), Rajiv Gandhi was assassinated, apparently by Tamil extremists from Sri Lanka. In the elections, Congress (I) won 213 parliamentary seats and put together a coalition, returning to power under the leadership of P.V. Narasimha Rao. This Congress-led government, which served a full 5-year term, initiated a gradual process of economic liberalization and reform, which has opened the Indian economy to global trade and investment. India's domestic politics also took new shape, as traditional alignments by caste, creed, and ethnicity gave way to a plethora of small, regionally based political parties.

The final months of the Rao-led government in the spring of 1996 were marred by several major political corruption scandals, which contributed to the worst electoral performance by the Congress Party in its history. The Hindu-nationalist Bharatiya Janata Party (BJP) emerged from the May 1996 national elections as the single-largest party in the Lok Sabha but without enough strength to prove a majority on the floor of that Parliament. Under Prime Minister Atal Bihari Vajpayee, the BJP coalition lasted in power 13 days. With all political parties wishing to avoid another round of elections, a 14-party coalition led by the Janata Dal emerged to form a government known as the United Front, under the former Chief Minister of Karnataka, H.D. Deve Gowda. His government lasted less than a year, as the leader of the Congress Party withdrew his support in March 1997. Inder Kumar Gujral replaced Deve Gowda as the consensus choice for Prime Minister of a 16-party United Front coalition.


In November 1997, the Congress Party in India again withdrew support for the United Front. New elections in February 1998 brought the BJP the largest number of seats in Parliament--182--but fell far short of a majority. On March 20, 1998, the President inaugurated a BJP-led coalition government with Vajpayee again serving as Prime Minister. On May 11 and 13, 1998, this government conducted a series of underground nuclear tests forcing U.S. President Clinton to impose economic sanctions on India pursuant to the 1994 Nuclear Proliferation Prevention Act.

In April 1999, the BJP-led coalition government fell apart, leading to fresh elections in September. The National Democratic Alliance-a new coalition led by the BJP-gained a majority to form the government with Vajpayee as Prime Minister in October 1999.