REPORT OF THE DIRECTOR I920-2I 139 



the belt on the eastern hemisphere; and to overlook the fact that 

 the Poseidon sea, which was to the northwest of the African 

 portion of the belt, should also have exerted a distinct influence 

 in southeast direction, as it did toward Laurentia in northwest 

 direction. 



If then there is recognizable a distinct east-west component in 

 the northern belt of Precambrian folding (to some extent also 

 suggested by the folds of the southern hemisphere), and further, 

 the north-south direction of the Archi-Gondwana or equatorial 

 belt is not satisfactorily explainable by the influence of the two 

 primordial oceans, we may well ask ourselves what these influences 

 could have been. 



The fact that these components of the fold directions appear 

 in two, or more probably three (including that of the southern 

 hemisphere) belts of folding, seems to suggest that factors of a 

 greater scope than the primeval differences of density of the conti- 

 nents and oceanic underbodies may have controlled the trend lines 

 of Precambrian folding. 



These factors can be sought in changes of the velocity of rotation 

 of the earth and in primordial tidal waves of the earth's crust. 



We do not feel competent to enter upon a technical discussion of 

 the influences of these cosmic factors upon the earth's crust. We 

 shall therefore but roughly and briefly point out the possibilities 

 of their influences, as we understand them. 



Suess, although considering the contraction of the earth as the 

 principal cause of mountain folding and believing the folding to 

 arise from the dragging of the outer crust by deeper portions of the 

 same, was nevertheless inclined to set beside this interior cause of 

 the changing of the earth's surface features, also the exterior causes 

 mentioned above. He says (Suess-Sollas, v. 4, p. 607) : 



" Darwin states that if bodily tides influenced the arrangement 

 of the mountain chains, then we should expect to find at the equator 

 a north and south strike, toward the north a northeasterly strike, 

 and toward the south a southeasterly strike. This supposition 

 holds for almost the whole of the Pacific region. The advance of 

 the Antilles toward the east, the arrangement of all the arcs of 

 eastern Asia and the Oceanides, and in particular the fact that 

 almost all the Asiatic virgations open toward the west and south- 

 west are consistent with the theory. But there is no lack of excep- 

 tions; the St Elias range is folded toward the west or southwest, 

 likewise the great Burman arc and the Urals. The whole of that 

 part of the western Altaides lying outside the horst of Azov is 

 opposed to the rule. 



