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.