Message #121209

[dhill757]

4. Up to now we had been discussing the possibility of a fairly fast glacio-eustatic rise of the mean sea level. But in modelling the dynamics of the changes in the relative sea level for a specific region, besides the glacio-eustatic fluctuations of theme an sea level connected with the changing volume of the ice sheets, it is also necessary to take into consideration the changes in the absolute level of the earth surface, determined by the glacio-isostatic effects.

As we have already said in section "WHERE",at the time when the Scandinavian ice sheet existed, the earth crust beneath it was isostatically depressed under the weight of its mass, while at a distance from it, the crust was uplifted as a result of the isostatic balancing. If the area of the Celtic Shelf was situated in the zone of this uplift, so that the relative sea level there was lower than the mean sea level by the amount of this isostatic elevation, then, as the Scandinavian ice sheet receded and diminished, and the compensatory processes of the uplifting of the earth crust in the area of the ice sheet itself were taking place, and simultaneously its subsidence in the area which was uplifted, the speed of the rise in the relative sea level in the area of the Celtic Shelf constituted the sum of the speed of the glacio-eustatic rise in the mean sea level and the speed of the isostatic subsidence of the surface of the earth crust in this area.

The time scale of such isostatic processes is not quite clear. Their speed depends on a variety of factors, such as the toughness of the earth crust, the size of the blocks that are being balanced, the depth at which the isostatic balancing takes place, and the estimate of this speed depends to a great extent on the choice of this or that model of the structure of the Earth. Most researchers agree that in the wake of the disappearance of most of the ice sheets, the speed of the compensatory isostatic uplift and subsidence was substantially higher than can be observed now that the disappearance of the glacio-isostatic pressure of the ice sheets of the last glaciation has practically been compensated in full (23, 33).

If we assume that at the end of the last glaciation there had been a massive discharge of ice from the Scandinavian ice sheet similar to the "Heinrich events", then the decrease of the glacio-isostatic pressure could have been leap wise, and the compensatory isostatic processes could have developed with the maximum possible speed.

5. Another argument to back the thesis that none other than the rising of the sea level was the catastrophe that Plato described, is that the relief of the plain in point, in the west of Europe, was of such character, that the rising of the sea level by one meter could often have meant the retreat of the coastline by kilometers. I am sure that even if the full submerging of the territory lasted several years, the eye-witnesses (and victims), who were on a flat plain, must have perceived it as a very fast sinking of all the land they could see, from horizon to horizon (See again map of the Celtic Shelf).