At the beginning of the twentieth century it was thought that the Earth and the other planets were formed of matter torn from the Sun. And the image of an Earth circulating in a gradual process of cooling, from incandescence to bright red, then passed to a moderate heat and finally to the boiling point of water. Once cooled enough for the water to condense, the water vapor from the hot atmosphere of the Earth went into a liquid state and began to rain, and rain, and rain and ...
After many years of this incredible rain of boiling water that jumped and bellowed when it hit the hot ground, the basins of the rugged surface of the planet eventually cooled down enough to retain water, fill and thus constitute the oceans.
Very spectacular ... but absolutely false, we could almost assure.
Today, scientists are convinced that the Earth and other planets were not formed from the Sun, but from particles that conglomerated towards the same time when the Sun was taking shape. The Earth was never at the temperature of the Sun, but it acquired a lot of heat thanks to the collision energy of all the particles that formed it. So much so that its relatively small mass was not able at first to retain an atmosphere or water vapor.
Or what is the same, the solid body of this newly formed Earth had neither atmosphere nor oceans. Where did they come from then?
Of course there was water (and gases) weakly combined with the rocky substances that constituted the solid portion of the globe. As that solid portion was packed more and more compactly under the pull of gravity, the interior became increasingly hot. The gases and water vapor were expelled from that their previous combination with the rock and abandoned the solid substance.
The gaseous bubbles, when formed and grouped, shocked the young Earth with enormous cataclysms, while the heat released caused violent volcanic eruptions. For many years not a drop of liquid water fell from the sky; it was rather water vapor, which whistled out of the crust, and then condensed. The oceans formed from above, not from below.
What geologists disagree today is the speed of ocean formation. Did all the water vapor come out in a billion years, so that the ocean is the current size since life began? Or is it a slow process in which the ocean has been growing through the geological ages and is still growing?
Those who maintain that the ocean formed at the very beginning of the game and that it has kept a constant size since then, point out that the continents seem to be a permanent feature of the Earth. It does not seem that they were much larger in times past, when it was the ocean supposedly much smaller.
On the other hand, those who believe that the ocean has been growing steadily, point out that volcanic eruptions still spill huge amounts of water vapor into the air: water vapor from deep rocks, not from the ocean. In addition, in the Pacific there are underwater mountains whose tops, flat, may have been at sea level before, but are now hundreds of meters below it.
Perhaps it is possible to reach a compromise. It has been suggested that, although the ocean has been growing continuously, the weight of the accumulated water caused the seabed to subside. That is, according to this hypothesis, the oceans have grown constantly in depth, but not in width. Which would explain the presence of these submerged marine plateaus and also the existence of the continents.
|A planet of water|