7.2 Geological History of Earth and the Life on it

7.2.1 Plate Tectonics Ocean floor surveys undertaken in the 1950s found that the mightiest and the most extensive mountain chains on earth are mostly underwater. Starting from Iceland, if one travels south, one could follow it down the center of the Atlantic ocean ( known as mid Atlantic ridge ) around the bottom of Africa and then across the Indian and Southern Oceans and into the Pacific, just below Australia. From there, it shoots up to the West Coast of United States to Alaska. Occasionally, some of its peaks stand above water as islands like the Canaries in the Atlantic or the Hawaii in the Pacific. When all these branches are added together, the network of the mountain chain extends to 75000 Kms. In the Bay of Bengal, we have a similar ridge, known as the 90O E (Longitude) ridge.



7.2.2 Down in the middle of the mid-Atlantic Ridge is a Canyon, a rift, upto 20 Kms wide for its entire length of about 19000 Kms. In the 1960s core samples of the rock from the ocean floor showed that the ocean floor was quite young at the mid-Atlantic ridge but grew progressively older as one moved away from it, both to the East and the West. This could only mean that new ocean crust is being formed on the Central Ridge and the older ones are being pushed away to either side. In other words, the sea floor is spreading. The Atlantic ocean floor is effectively functioning as two large conveyor belts, one carrying the progressively older crust from the centre towards North America and the other towards Europe.

7.2.3 When the oceanic crust reaches the boundary with the continents, it plunges back into the bowels of the earth in a process known as subduction. That is where all the sediments carried by the rivers from the land to the sea went and were consigned to the bowels of the earth. That explains beautifully why the ocean floors everywhere are so young, (none older than about 175 million years) whereas the land in the continental crust is as old as 4.5 billion years. A beautiful illustration of “ Atma Yoni Swayam Jataha” ! It was realized that the earth was a mosaic of interconnected segments whose various jostlings accounted for the planet’s surface behavior, like the sub-sea volcanic eruptions, earthquakes, tsunami, all happening around the junction of two plates in the subduction zones which are mostly arcuate in shape (archer) and with tremendous amount of sound (saamagaana). This science is called “plate tectonics”.

7.2.4 The earth’s surface is made up of 8 to 12 big plates and another about 20 smaller plates and they all move in different directions and at different speeds. It was one such movement of the Indian plate from Antarctica to the North and East over millions of years and its collisions with the Asian plate that resulted in the mighty Himalayas. It was the subduction of the Burmese – Indonesian plate beneath the Indian Ocean which created the huge earthquake of 2004 and the hugely destructive tsunami that killed thousands in Indonesia, Andaman Islands, Sri Lanka and the East Coast of mainland India. The landscape of Andaman Islands has significantly changed in certain parts as a result. Yes, “ Mahahavis” was offered to Him in the subduction zone and he reduced the size of the world, (Samkshepta) and He was Sangarshana Achyuta- grappled all the objects and destroyed them while He himself remained unaffected; in this case the sea was unaffected. The geologists predict that, in a not too distant date from the geological time scale, in about 250 million years from now, the Supercontinent, known as Pangea, which started spreading and splitting to form different continents from the Permian age to present day, will again form “Pangea Ultima”, as a result of the subduction of the ocean floor of the North and South Atlantic beneath Eastern North America and South America. This supercontinent will have a small ocean basin trapped at its centre (Similar to Caspian sea of present day) and the Mediterranean sea and Atlantic oceans would have disappeared. Once again, a scientific evidence of what is likely to happen millions of years hence, for the cyclicity of Creation, Sustenance and Destruction, the basic concept of Hindu Philosophy.

7.3 Bacteria

7.3.1 And, how about life itself? We already saw in some of the earlier chapters the role of the blue-green Algae as a precursor of photosynthesis and a source of oxygen for the atmosphere for the later more evolved beings to live. We saw the role of amino-acids, proteins, DNA and the cells and how they function. Let us see a little more about some of the lives that can be seen only with the help of a microscope.





7.3.2 Bacteria got along for billions of years without us. But, we cannot survive a single day without them. They process our waste and make them useable again. They purify water, keep our soil productive, convert what we eat into useful sugars and poly- sacharides and go to war on alien microbes. Bacteria take Nitrogen from air and convert it to amino acids for us. Algae and other microbes blow out about 150 billion Kgs of oxygen every year into the atmosphere for us to breathe.

7.3.3 The bacteria are also prolific. A single bacterium can theoretically reproduce 280,000 billion individuals in a single day, according to the Nobel laureate Christian de Duve. In the same period the human cell can just manage a single division. Microbes can survive on anything, given only a little moisture. A species called “Micrococcus Radiophylus” was found living and thriving in the waste tanks of nuclear reactors. Bacteria have been found living 11 Kms down in the Pacific Ocean, where the pressures are 1100 times more than at the surface of the sea. An extraordinary discovery was the find of a “Streptococcus” bacterium that was recovered surviving from the sealed lens of a camera that had stood on the moon for two years. Bacteria are found living in temperatures higher than 100 degree Centigrade. In short, there are few environments in which bacteria cannot exist.

7.3.4 At depth, microbes shrink in size and become extremely sluggish. The most active of them may not divide more than once in a century. In 1996, scientists at the Russian Academy of Science claim to have revived Bacteria frozen in Siberian permafrost for 3 million years.

7.3.5 If the little world of atoms stand for what is “Vishnu”, in the domain of physics, the “microbes” can certainly lay claim on “Vishnu” in the field of biology. The microbe indeed represents the concept of “Sthavira Dhruvaha”- Old and stable, “ Agrahyah”- cannot be understood by organs of action,” Bhugarbha”- protects the earth in constant turmoil, “Kramaha”- occupies everything on earth,” Sarvagaaya”-goes anywhere and everywhere, and many other similar names of Lord Vishnu.

7.4 Extinction

7.4.1 While complex life started blooming for the first time in the Cambrian period, about 540 million years ago, the Earth has seen five major periods of extinction ( deluge or pralaya) besides many smaller ones. The Ordovician (about 450 million years ago) and Devonion (about 365 million years ago) wiped out about 80-85 % of the species on the surface of the Earth. But, the Permian period (about 245 million years ago) the end of what is known as the Palaeozoic era saw the disappearance of about 95 % of animals and about 1/3rd of the insect species also. In the next Mesozoic era, the Triassic (about 210 million years ago) and the Cretaceous( about 65 million years ago) each wiped out about 70-75 % of the species then living. In each case of these extinctions we have very little idea of what caused them. Various reasons have been attributed like global warming, global cooling, change of sea level, oxygen depletion in the sea, epidemics, giant leaks of methane gas from the sea floor, meteor and comet impacts, hurricanes and tsunamis , volcanic upwellings, and huge solar flares.







7.5 Survivial
7.5.1 But, even more incomprehensible is the fact that while 70-75 % of life then existing vanished at the end of each of these episodes, what conditions favored the remaining 20-25 % species to survive. For example, while the dinosaurs disappeared without a trace at the end of the Cretaceous period, how did other lizards like turtles survive? In fact, the next period after the dinosaurs is often referred to as the age of the turtles ( is that why “ Kurma-Avataar” is celebrated as the next to “ Matsya-Avataar”, the age of the fish ?). Again, while all the Ammonites disappeared at the end of the Cretaceous, how did Nautiloides living in similar environments survive till date ? ( Is that why the memory of Ammonites commemorated as “Saligramam” when they are found in fossilized nodules ?) Yet again, while 92 % of uni-cellular foraminifera were wiped out, in the Tertiary era other similar organisms living alongside like diatoms, besides a few other foraminifers were left untouched till date. Is that why, again symbolically, the sands from the river beds or sea beds are taken and worshipped in many pujas and rituals, in commemoration of these millions ? Again, cockroach, is perhaps the only insect that continues to exist from Cambrian period till date with little or no evolutionary change. These continue to remain as mysteries.

7.5.2 Indeed, He is “Viswadhrut- Unmindful of good or bad, sustains the Earth”, “Viswabhuk”- Eats the world at the time of deluge, “Yugaadikrut”- created the different periods and after the deluge , “Yugaavarta”-created the different periods again and again, “Mahaasanaa”- Eats a lot because He devours large chunks of earth and species of life, “Sangarna Achutasha” and “Samkshepta”- Reducing the size of the world and its activities at the time of the deluge and many such names by which He is worshipped.

7.5.3 We must however, remember, that whatever survival numbers have been quoted are based on very restricted data from areas studied. For instance, the tropical rain forests cover only 6 % of the Earth’s surface but they harbour more than half its animal life and about 2/3rd of its flowering plants. Much of it is unknown to us since very few research workers spend time on them because of their environmental inaccessibility. For instance, more than 90 % of the flowering plants have not been tested for their medicinal properties. Because they cannot fly from their predators, these plants by nature, develop chemical defences and are therefore, rich in valuable chemical compounds. Currently about 25 % of all prescribed medicines are derived from just 40 plants in allopathic medicine system. We can imagine the future role for the tropical plants and the Ayurvedic and Siddha Systems of medicine if this is properly tapped.

7.5.4 Yes, He is “Dharaneedhara”- he who holds the world, “Jagatsetava”-Shores up the world separating the good from the evil, “Vikarta”- Creator of this world with myriad plants and animal lives, “ Sameehana”-Likes the role of creation and many other names by which He is worshipped.