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THE UNIQUE EARTH AND GEOMORPHOLOGY ( Page 3)
Nor is this the final picture, the geologists tell us. Plate movements shall continue. Geologists predict a possible scenario for 50 million years from now which could include the following changes if not more.
1) On the western side of North America, the California plate will break off from the mainland completely and stay as a long island.
2) North and South America will again separate, replacing the man-made Panama Canal with a natural link between Pacific and Atlantic.
3) Even the Suez will open up and give natural link between red sea and the Mediterranean.
4) The great lakes of East Africa will join up and form a sea like the red sea, separating much of East Africa from the mainland.
5) The Persian Gulf will disappear when Arabia joins up with Asia.
6) Most of the landmass except the Antarctica will move further north.
7) Atlantic and Indian Oceans will become larger at the expense of the Pacific.
These predictions for the future regarding the changes in the continental structure cannot in any way give any view of the distribution of life 50 million years from now, not even 5000 years from now.
Uniqueness of the Earth
Life, as we know it, cannot exist everywhere. Certain preconditions are necessary for its origin and survival. The earth and the solar system have met these conditions and that is one of the things that makes this part of the universe so unique. There are many facts that make the earth a very unique place. Let me try to get a general picture of this based on the most recent findings or conclusions of cosmologists.
Our galaxy itself is unique. There are many galaxies and globular clusters where life cannot exist in any part of them because of the nature of star distribution as well as the intensity of radiation levels in these. There could be other galaxies similar to ours. We are not sure of this. In our galaxy itself all parts are not ‘habitable’. The astronomers have charted a ring in the galaxy, which they call the ‘galactic habitable zone’. Sun happens to be in this ring. This is far from the centre of the galaxy but not quite at the edge. We are privileged to be in the residential area. Within the solar system also there is a ring of ‘habitable zone’. This includes only three planets – Venus, earth and mars. Any closer to the sun, and it will be too hot. Any farther from the sun and it will be too cold. And we know that our earth is at the centre of this residential area.
The presence of the very heavy elements like iodine, gold and uranium is quite an intriguing aspect unique to our solar system. Such heavy weights cannot be produced by the nuclear fusion processes that take place even in the largest of stars. These are manufactured during the collision of two neutron stars. Neutron star collisions are so rare and the fact that our star, the sun, was born in the area of the cosmos where this rare occurrence had taken place also makes our home a unique one. It is not just the lustre of Gold or the fissibility of uranium that will be missing in most other planets of other solar systems but the presence of many elements like iodine that are necessary for life.
The speed and period of rotation and revolution of the earth, the tilt of the earth on its axis in the solar orbit, all these makes the days and nights, seasons and years as well as climatic conditions conducive to life on the planet. Imagine the earth always facing the sun with perpetual daylight for one half and everlasting night for the other half. Or imagine the same weather conditions all the 365 days of the year. How unbearable it all could be! The size of the planet is also significant. If it were much smaller or lighter there would have been no atmosphere. If it was much bigger or heavier the atmospheric pressure would have been too much and all undesirable gases would have been here. This is because gravity determines the escape velocity that decides whether the gases will fly away or stay. The earth is the right size. Not too large, not too small. Some other mysteries that surround our earth include the magnetic field, the ionosphere, the Van-Allen belt and the ozone layer. These are the protective shields that prevent harmful and lethal radiations from reaching the earth. These radiations could be detrimental to life or could have inhibited the origin of life.