Tuesday, November 22, 2011

The legend of Gondwana resurfaces....

The legend of Gondwana resurfaces....By Raja Murthy

MUMBAI - Remains of the lost supercontinent of Gondwana surfaced again last week, with Australian scientists discovering bits of this gigantic land mass that once linked Asia and India with Australia and Antarctica.

Sydney University geophysicist Jo Whittaker said this "exciting discovery" could reveal how the supercontinent of Gondwana broke into present-day Australia, Antarctica and India between 60 and 130 million years ago. At that time, called the Cretaceous period, the dinosaurs were lords of the Earth roaming across a mammoth mass of land that may have connected where Tokyo, Perth, Kolkata and other Asia-Pacific cities now stand.

How different could have been the histories of India, Japan and the world if the continent of Gondwanaland had not splintered into pieces in the Indian Ocean? That all phenomena are in a constant flux of change, and that whatever happens has positive outcomes and silver linings, is truth applicable to supercontinents too.

Geologists say an even bigger monster land mass called Pangaea existed over 200 million years ago, surrounded by one universal ocean called Panthalassa. The northern half of Pangaea was the other supercontinent called Laurasia. Gondwana was the southern supercontinent.

Scientists from Sydney University, Macquarie University, University of Tasmania and from Israel were part of an expedition that found the two islands that may be bits of Gondwana on the seabed in international waters 1,600 kilometers (1,000 miles) west of Perth. Soil samples they collected during their deep sea expedition this October could be one billion years old, they said.

Gondwana is of particularly interest, since the chunk of land that is now India moved northwest away from the Australian continent, then drifted north and northeast, according to geologists. The eastern piece of Gondwana coast crashed into Eurasia, forming the mighty Himalayas. The Himalayas became protective guardian wall for human life and civilization to flourish in the Indian sub-continent.

Gondwana could be the motherland for most people on Earth, with this supercontinent forming half of current land mass. Besides Antarctica, Australia, India and Sri Lanka, Gondwana included what are now Africa, South America and New Zealand.

The continent of Gondwana fascinates geologists. Plate tectonics - the study of geological activity beneath the Earth's surface - is an infant science that gained wider acceptance only about 60 years ago. A German meteorologist Alfred Wegener in 1912 had first declared theory of continental drift that applies to Gondwana. Geologists are still learning the basics how continents move and collide. Continents are moving every second, as is all phenomena in constant flux.

Dr Bhaskar Rao, a leading Indian geologist and director of the National Geophysical Research Institute (NGRI), said that understanding Gondwana and how continents were formed and broke up is very important for climatic, environment reasons, as well as in the search for mineral resources.

"Study of Gondwana is of particular significance to India since the volcanic eruptions of the Deccan Plateau in central India happened about 60 million years ago," Rao told Asia Times Online. "This is about the same timeframe of the breakup of the Gondwana supercontinent."

Rao, a former postdoctoral research fellow at the University of Minnesota in the United States, convened the 8th International Symposium "Gondwana to Asia Supercontinent Dynamics: India and Gondwana" in Hyderabad this August, as part of the Golden Jubilee celebrations of NGRI. The International Association of Gondwana Research in Japan was the co-organizer.

"India’s Lakswadeep Islands [meaning 'hundred thousand islands' in India’s coral belt off the eastern coast] was also part of the Gondwana break-up," Rao said. "So too is Madagascar, off the southeastern coast of Africa."

The supercontinent strikes deep enough chords in India for a province to be named Gondwana - a former administrative region covering parts of what are the modern Indian states of Maharastra, Madhya Pradesh, Orissa and the Deccan Plateau that straddles western, eastern and southern India.

Gonds are the medieval tribal population inhabiting India’s Gondwana region. Said to be among the largest tribal groups in South Asia, the earliest recorded presence of Gonds was in the 14th century - over 60 million years after Gondwana broke up.

The 15-member expedition in October-November, aboard Australia's leading ocean exploring ship RV Southern Surveyor, aimed to find more about how Australia and India were separated, and more about the "de Gonneville Triangle" - the oceanic crust that formed junction of Australia, India and Antarctica. It could hold key to how and why Gondwana broke up into separate land masses. [1]

Besides the Himalayas, the Alps too were squeezed out upwards when Africa separated from the South American land mass and crushed against Europe. Appropriately for this universality in collision of continents, a Gondwana theme park "Gondwana - Das Praehistorium" thrives in Landsweiler-Reden, Germany, giving visitors a glimpse of what life could have been in Gondwanaland.

The Gondwana rocks that scientists discovered in the Indian Ocean last month contained fossils of creatures found in shallow waters. It meant they were once part of the continent at or above sea level rather than created by undersea volcanic activity, said expedition members.

"We have a fairly good idea where those continents were but we don't exactly know, the eastern Indian Ocean is one of the more poorly explored parts of the world's oceans in terms of tectonics," Jo Whittaker told news agency Agence France-Presse. "So it will help us figure out the plate kinematic motions that led to India moving away from Australia and heading up off to crash into Eurasia."

The rocks would be compared with the samples from Australia's west coast to see exactly where the islands broke away. What was the Indian coast to the Gondwana land mass cannot be matched as that crashed coast is now somewhere high up in the Himalayas.

Professor Whittaker, a postdoctoral fellow in the School of Geosciences in Sydney University, is studying Indian Ocean plate reconstructions and continental break-up as part of a research project on "Gondwanaland extension, breakup and continental margin evolution".

Various theories periodically emerge about why Gondwana broke up, and whether it just split into two major chunks - with the Indian sub-continent and Australia - or whether it splintered into many more bits of land that comprise other Asian countries. [2]

Other major Gondwana research efforts include those from the International Association for Gondwana Kochi University in Kochi, capital of Shikoku island of Japan. The Japanese Gondwana University focuses on research in origin and evolution of continents, particularly Gondwanaland and its crustal fragments.

The study of Gondwana, and the plate movements beneath the Earth's crust, throws light on the movement of the deadly tsunami waves. Tsunamis are caused by earthquakes that in turn are caused by continental restlessness of the plates beneath the Earth's surface.

The Australia continent is currently traveling north at seven centimeters (2.75 inches) a year, and the catastrophic 2004 earthquake and tsunami were linked to such plate movements and subterranean collisions. Getting to know better what happened to Gondwana could save thousands of lives.

1. Objectives and Voyage plan of the 15-member expedition aboard the Southern Surveyor, led by chief scientist Simon Williams:
The Perth Abyssal Plain: Understanding Eastern Gondwana Break-up.
History of Ancient Supercontinent Detailed. Live Science, April 28, 2008.

The Gondwana supercontinent underwent a 60-degree rotation across Earth's surface during the Early Cambrian period, according to new evidence uncovered by a team of Yale University geologists. Gondwana made up the southern half of Pangaea, the giant supercontinent that constituted the Earth's landmass before it broke up into the separate continents we see today. The study, which appears in the August issue of the journal Geology, has implications for the environmental conditions that existed at a crucial period in Earth's evolutionary history called the Cambrian explosion, when most of the major groups of complex animals rapidly appeared.

Gondwana Shift: The paleomagnetic record from the Amadeus Basin in Australia (marked by the star) indicate a large shift in some parts of the Gondwana supercontinent relative to the South Pole....