388 B. M. S. Watson— The Beaufort Beds, South Africa. 



globe of rock?" The cores of continents and mountains are found 

 generally to consist of crystalline igneous rocks, and the simplest 

 explanation of isostasy seems to be that these crystalline igneous 

 rocks have arisen from below by vertical expansion. I beg to suggest 

 that if great cracks occur at depths of miles in the sub-crust the 

 rocks may be so disturbed by lateral pressure as to undergo chemical 

 change, and to expand vertically. Mr. Fisher argues that lateral 

 pressure should lead to increase of density. If rock be subjected to 

 compression from all sides its density would increase, but if the 

 pressure is from one side only, and the rock is able to escape 

 vertically, an increase of density may rot ensue. 



8. Mr. Fisher states that any deep rift in our globe must at once 

 be filled by heavy intrusive molten rock rising from below. He 

 cannot accept the view that the solid globe may be cracking, and 

 that the cracks are being filled by material from above. But is the 

 intrusion of molten rock from below dependent at all upon depth ? 

 Such intrusions are to be seen at high continental altitudes, whilst 

 the great oceanic deeps remain unfilled by them. 



It is, I think, conceivable that the outer shells of a solid planet 

 might become cracked in all directions, and that if the planet were 

 devoid of atmosphere and oceans, as Mars possibly is, the cracks on 

 its surface might be visible. If the outer shells of a solid globe were 

 cracking, a condition resembling hydrostatic equilibrium might be 

 produced. As a crack was opening the lateral pressure would suffice 

 to increase the elevation of ridges along its edges, and when the 

 opening force declined the weight of the elevated ridges would tend 

 to close the crack. There would thus be a resilience that would lead 

 to oscillations of level. 



9. Suess has suggested that the Himalaya Mountains are advancing 

 southwards, and that the Japanese Islands are moving outwards 

 towards the Pacific Ocean. The geodetic observations in India lead 

 me, however, to believe that the Himalaya Mountains are being forced 

 northwards by the opening of the Indus-Ganges crack, and that the 

 Japanese Islands are being pressed backwards against the continent 

 of Asia by the opening of the Tuscarora Deep. I think that the 

 elevation of the Japanese Islands and their movement westwards as 

 the Tuscarora Deep opens, may possibly teach us how continents and 

 mountains originate and grow. 



II. — Thk Beaufort Beds of the Kaeego System of South Afeica. 



By D. M. S.Watson, M.Sc, Lecturer in Vertebrate Palseontology in University 

 College, London. 



rpHE great Karroo System of South Africa was divided by its 

 JL discoverer, Andrew Geddes Bain, into four formations on litho- 

 logical characters. They are — 



The Stoemberg Series. 



The Beaufort Beds. 



The EccA Beds. 



The DwYKA Series. 

 It has long been recognized that the Dwyka conglomerate, which 

 forms a large part of the lowest series, is of glacial origin, and the 



