382 THE PLAN OF THE EARTH AND ITS CAUSES. 



of Mr. E. D. Preston, show that geodesists are more inclined to regard 

 the theory with favor. It is at least clear that geodesy does not dis- 

 prove the hypothesis, and that some puzzling geodetic anomalies receive 

 a simple solution if the theory be true. 



GEOLOGY AND THE TETRAHEDRAL COIGNS AND EDGES. 



Let us now turn to geology, to see if its evidence as to the past his- 

 tory of the world refutes or supports the theory. 



The geological evidence ought to be of especial value, as we should 

 expect it to determine the position of the tetrahedral coigns on the face 

 of the earth. 1 



If the tetrahedral theory be true, the four tetrahedral coigns should 

 be areas of unusual stability and strength. Comparison of the three 

 meridional land belts shows that each of them begins in the north with 

 a vast block of Archaean rocks. The Eurafrican zone, in longitude 20° 

 E., begins with the block occupying Scandinavia, Finland, and Lap- 

 land, which Suess has termed the " Scandinavian schild." It is an 

 area of great geological antiquity, which has long remained above sea 

 level; bands of marine deposits of different ages sweep round it, but 

 the block may never have been below sea level. It has unquestionably 

 remained as a solid impassive block which has dominated the whole 

 geological history of northern Europe. South of the Scandinavian 

 coign are the transverse east and western chains of the Alps and the 

 Atlas, with the Mediterranean trough between; and far to the south 

 we have the old plateau of South Africa. 



Let us now go 120° westward to the American zone. It begins with 

 another block of old Archsean rocks, forming what Suess has called the 

 11 Canadian schild." It occupies Canada, Labrador, and most of Hud- 

 son Bay and Baffms Land, and underlies Greenland. Bands of marine 

 deposits surround it, but it has perhaps never been itself below sea 

 level ; its geological age, at any rate, is enormous. South of the North 

 American coign we have again a pair of east-west mountain chains, 

 forming the highlands of Cuba and Venezuela, separated by the Carib- 

 bean trough. This zone also ends southward in an old plateau resting 

 on Archsean rocks. 



The third meridional zone repeats the same characters. It begins 

 with a block of Archsean rocks, for which we may speak as the "Man- 

 churian coign." South of this coign are the east and west ridges of 

 Malaysia and the depressions parallel to them; and south of that, again, 

 we have the Archsean plateau of Australia. 



The three main land axes of the world have remarkable resemblances 

 in structure, and they present three equidistant blocks of great stability 

 at the three tetrahedral corners. We may therefore speak of the 

 "schild " as the three northern coigns or corner stones of the earth. 



1 They were assigned to their geometrical positions by Green, and in the interest- 

 ing recent tetrahedral volcanic map of M. Michel-Levy. 



