ASIA: 17,208,000 SQUARE MILES
AFRICA: 11,608,000 SQUARE MILES
NORTH AMERICA: 9,449,000 SQUARE MILES
SOUTH AMERICA: 6,880,000 SQUARE MILES
ANTARCTICA: 5,100,000 SQUARE MILES
EUROPE: 3,841,000 SQUARE MILES
AUSTRALIA: 2,970,000 SQUARE MILES
Out of the total earth area, around one-third is land, and balance two-third is water–ocean. Yet, the major land divisions—the continents—are the ones that give shape and physical identity to the planet.
The seven continents represent some 57 million square miles in area, portioned unequally among them. They range in size from Asia, being the largest, to Australia, being the smallest. Although Europe and Asia form one large mass, they are usually regarded as two continents, mainly due to the cultural differences between their peoples.
The seven continents as they appear today represent just one episode in an ongoing scenario of the wandering land masses. It is a process whose history dates back to the initial formation of continental material on Earth’s crust almost four billion years ago—a process called ‘plate tectonics.’
The crust and the top portion of the mantle form a rigid shell around the planet that is broken up into 16 large sections known as plates. Heat generated inside Earth is distributed through convection current which causes the plates to move slowly. This sort of movement has been going on for hundreds of millions of years.
Most geologists believe that the ‘continents’ were created when vast plates of rock collided, forcing one to slide under another in a process called ‘subduction.’ The crust then melted and formed magma, or molten rock. Erupting to the surface, the magma built volcanic islands that eventually fused with other islands on adjoining plates—becoming the first continental material.
HOW WERE CONTINENTS FORMED
As Earth’s continental masses grew bigger, moving all the while, they shifted in relation with each other and coalesced into different arrangements over hundreds of millions of years. The current configuration of continents is just a temporary one in the eons-long process of the plate tectonics.
Three times during the past billion years, drifting landmasses have merged to form supercontinents.
In between these stages of continental drift, they split into smaller landmasses before recombining again. Scientists predict that a new supercontinent, ‘Pangaea Ultima,’ will eventually form, 250 million years from now.
CONTINENT: Comes from the Latin continens, “held together.” One of Earth’s seven large masses of land.
TECTONICS: Comes from the Greek tekton, “builder.” Study of the changes in Earth’s crust and the forces that produce such changes.
SUBDUCTION ZONE: The oceanic trench area in which the seafloor ‘underthrusts’ an adjacent plate, dragging, accumulated sediments, downward into Earth’s upper mantle.
ALFRED WEGENER THE EARTH SCIENTIST
German Earth Scientist Alfred Wegener (1880-1930), was among the first to use balloons to track air currents. He participated in expeditions to Greenland to study polar air circulation but became better known for his theory of continental drift. People had already noticed that the coastlines of western Africa and eastern South America seemed to match, but Wegener found evidence that the continents had been joined: because of similar fossils from both sides of the Atlantic and tropical species in Arctic areas. He posited the existence of a supercontinent, Pangaea (All Lands) that eventually broke up, and he presented his ideas in the Origin of Continents and Oceans—but few believed him. In the 1950s and 1960s, studies of the ocean floor demonstrated a mechanism for crustal movement, is when Wegener’s theory of continental drift gained acceptance.
BRIEF HISTORY OF EARTH
500 MILLION YEARS ago, a chunk broke off a single continent. Shallow waters spawned the first multicellular creatures.
300 MILLION YEARS ago, some of today’s mountains formed. A new ice age covered Earth’s southern regions.
225 MILLION YEARS AGO, the earliest dinosaurs roamed a single continent that stretched from Pole to Pole.
100 MILLION YEARS ago, cracks across the one continent, known as Pangaea, formed rifts that evolved into oceans.
50 MILLION YEARS ago, a climate changing meteor crashed into Earth and the highest mountains began their uprise.
20,000 YEARS ago, ice sheets a mile deep gouged out the Great Lakes and then receded, raising sea levels.
Posted by Kamlesh Tripathi
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GLOOM BEHIND THE SMILE
(The book is about a young cancer patient. Now archived in 7 prestigious libraries of the US, including, Harvard University and Library of Congress. It can also be accessed in MIT through Worldcat.org. Besides, it is also available for reading in Libraries and archives of Canada and Cancer Aid and Research Foundation Mumbai)
ONE TO TANGO … RIA’S ODYSSEY
(Is a book on ‘singlehood’ about a Delhi girl now archived in Connemara Library, Chennai and Delhi Public Library, GOI, Ministry of Culture, Delhi)
AADAB LUCKNOW … FOND MEMORIES
(Is a fiction written around the great city of Nawabs—Lucknow. It describes Lucknow in great detail and also talks about its Hindu-Muslim amity. That happens to be its undying characteristic. The book was launched in Lucknow International Literary Festival of 2014)
REFRACTIONS … FROM THE PRISM OF GOD
(Co-published by Cankids–Kidscan, a pan India NGO and Shravan Charity Mission, that works for Child cancer in India. The book is endorsed by Ms Preetha Reddy, MD Apollo Hospitals Group. It was launched in Lucknow International Literary Festival 2016)
TYPICAL TALE OF AN INDIAN SALESMAN
(Is a story of an Indian salesman who is, humbly qualified. Yet he fights his ways through unceasing uncertainties to reach the top. A good read not only for salesmen. The book was launched on 10th February, 2018 in Gorakhpur Lit-Fest. Now available in Amazon, Flipkart and Onlinegatha)
RHYTHM … in poems
(Published in January 2019. The book contains 50 poems. The poems describe our day to day life. The book is available in Amazon, Flipkart and Onlinegatha)
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