REPORT OF THE DIRECTOR I92O-2I 



127 



Finally the paleogeographic maps of the Paleozoic era, here 

 reproduced in figures 2 and 3, clearly show that these same belts 

 were also the tracts along which the principal movements of the 

 seas and the separation of the continents took place in Paleozoic 

 time as is, for instance, well seen by following the paleogeographic 

 history of the Tethys. 



There existed, however, in Paleozoic time still another important 

 geosynclinal, folded and undoubtedly also seismic belt, namely that 

 which extended from Scandinavia through Caledonia in Predevonian 

 time and from Germany, France and southern England (Variscan 

 system) in Devonian time to North America (Newfoundland and 

 Appalachian system). This belt, which is now entirely inactive, 

 developed along the boundary of Archi-America (Laurentia) and 

 Archi-Eurasia and also marks the boundary of the eastern portion 

 of Archi-America and the old Poseidon (Archi-Atlantic) between 

 America and Europe and probably also (see Holtedahl's map, fig. 6) 

 that between the old " Atlantis " or " Eria " and the Arctic ocean 



Fig. 6 The structural elements of the North Atlantic- Arctic regions. A and B 

 the stable areas: ^A, the shields or positive areas; B, the neutral areas; C to 

 G, the post-Ordovician zones of folding; C, Pre-Downtowian time; D, Pre- 

 devonian time; E, Devonian; P, Late Paleozoic; H, areas of postulated 

 greatest vertical movement. After Holtedahl (1920). 



in the north. This ancient mobile tract has become submerged in 

 the greater event of the foundering that led to the formation of the 

 North Atlantic and that has produced a new mobile tract, inter- 

 secting the old one at nearly right angles. 



From these facts we believe that there is little doubt that the 

 principal mobile, seismic belts of the present earth in their general 

 direction still retain the fundamental boundary lines of the primeval 



