Wegener's Displacement Theory. 343 



When Africa and South America are joined, again the folds fall 

 into line. 



All this is striking ; but, to say the least, some of the statements 

 are rash. The existence of similar deposits in Spitsbergen and north- 

 east Greenland is not surprising, even on the old hypothesis. The 

 presence of Precambrian intrusives at two localities is not strong 

 evidence for bringing those localities together. Wegener asserts 

 that in the gneiss of the Hebrides and northern Scotland the strike 

 is north-east — south-west. The Survey Memoir on the North-west 

 Highlands gives the prevalent trend as west-north-west — east-south- 

 east or east — -west. If the asserted direction is evidence in favour of 

 the union suggested, the actual direction must be evidence against it. 



Whether the Caledonian system of folding has any real repre- 

 sentative in North America is still a matter of opinion ; but if west 

 and east were in contact when the folding and thrusting took place, 

 the intensity of the movement must have diminished with great 

 abruptness in the west. It is probable that there is some connexion 

 between the Appalachian and the Armorican folds, but the fact that 

 the two ends when brought together should coincide is not 

 remarkable. It is a more significant coincidence that a great circle 

 drawn along the Appalachian folds leads into and along the 

 Armorican folds, a fact which suggests, though it does not prove, 

 that they formed a continuous system, and that the visible portions 

 are in their original relative positions. 



Wegener's statement that the strike of the crystalline rocks in the 

 Sudan is from north-east to south-west is an instance of the manner 

 in which he ignores any observations that do not agree with his views. 

 It is not borne out even in the map by Lemoine,^ which he repro- 

 duces. He admits that the map does not show his point very well, 

 but says that it was drawn for other purposes. No doubt he is 

 right. Lemoine was collecting facts and not supporting hypotheses. 

 If we refer, by way of example, to Falconer's account of Northern 

 Nigeria,^ in which the strikes observed at many localities are 

 recorded, we find that the direction varies,, but, in the majority of 

 cases, it lies within a few degrees of the meridian. Either the strike 

 is too variable to support Wegener's generalization, or the change 

 takes place several hundreds of miles from the position he assigns 

 to it. 



On the other hand, the assertion that south of the Cameroons the 

 strike is north to south is an example of the way in which Wegener 

 draws wide conclusions from the most slender evidence, if the 

 evidence is what he wants. Lemoine is more cautious. He says 

 that the records hitherto published are very scanty, but they suggest 

 that the zones of folding are sensibly parallel to the coast and hence 

 approximately north — south. 



^ P. Lemoine, Afrique occidentale. Handbuch d. Reg. Geol., p. 57. 

 * J. D. Falconer, The Geology and Geography of Northern Nigeria, London, 

 19n. 



