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The Clam-shell Expansion



If we trace the stages of growth of the planet from Pangaean Earth, described in the last chapter, to the present day - it describes a lop-sided development of new crust. In other words, most of the new crustal surface required for a much larger Earth has been formed on one side of the planet, namely in the Pacific Ocean bed area.


I liken this lop-sided development of the Earth’s new crust to that of the opening of a clam-shell. The original super-continent Pangaea divided into two main parts, the northern part named Laurasia (Euro-Asia and North America) and the southern part, known as Gondwana (Africa, India, Australia, Antarctica and South America).


If we imagine Laurasia to comprise the top component of the clam-shell and Gondwana the lower one, with its hinge in the Mediterranean area - a ‘closed’ clam-shell would represent Pangaean Earth, 320 million years ago. As the clam-shell opens its ever widening ‘gape’ represents the new-ocean bed being formed. When the clam-shell is at maximum gape, the Pacific and Indian Ocean beds are fully developed.


The clam-shell started to open when Antarctica began to split away from the far eastern coast of Asia. This occurred in the early Permian Period and coincided with the break up of Pangaea into the two super-continents mentioned.


The progressive opening of the clam-shell is depicted in the left-hand series of images.






Euro-Asia (Laurasia)  ...... ........... Silver blue

India (part of Gondwana)............ White

Australia (part of Gondwana) ......  Beige

Africa  (part of Gondwana) .........  Red

New Guinea (part of Gondwana)..  Green

Pacific Ocean Bed (new crust)....   Blue


The following set of images gives more detail of the stages of the clam-shell opening, the planetary diameter as a percentage of the present one, and the geological period during the stage.  































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