Figure 4 – Sea-floor spreading

constant eruption at the crest of oceanic ridges causes the rupture of the oceanic crust and the new lava wedges into it, pushing the oceanic crust on either side as shown in figure 4. The ocean floor, thus spreads. But this spreading does not cause the shrinking of the other. Hess argued about the sinking of the crust which was spread in the trench system and does it gets consumed. On analysis, it was found that 2 cm/year is adequate for separation of South America from Africa in about 200 million years.