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The liquid mantle below the crust acts in a similar way - hydrostatic forces build up (I will describe the mechanism in a subsequent chapter) and forces its magma up through weak points in the Earth’s crust such as mid-ocean ridges and other volcanic areas which act as nature’s relief valves.


Summary of Clam-shell  Expansion


The clam-shell theory describes the development of the Earth’s crust in first the Pacific Ocean area and then the Indian Ocean area. The clam-shell opening began when the old integument of the Earth’s crust (now continental crust) ruptured along a line between east Asia and Antarctica).


The Indian Ocean-bed, which subsequently separated India and Australia from Africa can be seen as an extension to the Pacific Ocean-bed, towards the final stages of the clam-shell expansion.


The clam-shell opening came to a maximum about 60 million years ago and since that period the ocean beds on the other side of the planet (north and south Atlantic) became dominant in their development.


The Clam-shell opening, therefore, continued for a period of about 260 million years and was responsible for the Earth increasing its surface area by some  240 million km2. During its opening, continental masses and their peripheral geological structures (eg. karst landscapes, half-basins, and fragmented igneous provinces) became separated vast distances from their original connections. For example, karst Landscapes of the Madre de Dios Islands on the western tip of South America where once continuous with those of the Thailand peninsula. The peninsula of Antarctica compares geographically and geologically with its former near neighbours, Wrangel Island off the East Siberian Coast, and the tip of Baja California, Mexico.


Mars may be commencing a clam-shell expansion stage and it appears that its integument has ruptured at the Valle Marinaris. If this is so, it is happening at exactly the same stage of planetary metamorphosis as happened here on Earth.





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