258 ANNUAL REPORT SMITHSONIAN INSTITUTION, 192 8 



hypothesis these slight similarities should be striking identities^ and 

 many of the marine faunas, for instance, should have, not 5 per cent 

 of identical species, as is actually the case, but between 50 and 75 per 

 cent, which is not true at all. 



COMAGMATIC SIMILARITIES 



The petrographic similarities have been treated fully by H. S. 

 Washington,^ who finds some between North America and Europe, 

 but more between Africa and South America. About the latter 

 region he says, however (pp. 344, 346) : 



It thus seems to be evident that grave petrogiaphical nud chemical discrep- 

 ancies exist between the rocks of the Giiiana-Ceara coast and that of Guinea. 

 . . . The balance of the petrographical evidence [between Brazil and Africa] 

 may, then, be regarded as adverse to Wegener's hypothesis. 



Washington's conclusions regarding North America and Europe are 

 even less satisfactory. 



TECTONIC SIMILARITIES 



African Cape Mountains and Argentinian Sierras. — In the 

 extreme south of Africa are the east-west-trending Zwarte-Berge or 

 Cape Mountains, which are thrust to the north. In the east they go 

 straight out to sea but in the west turn and strike northwest. It is 

 plain that they have risen out of a typical geosyncline and accord- 

 ingly must originally have been considerably longer than they are at 

 present. Furthermore, there must have been a borderland to the 

 south some hundreds of miles across, from which the main mass of 

 sediments came. This broken-off (rias) ending of the Cape Moun- 

 tains has always been explained by downfracturing of portions of 

 South Africa both on the east and on the west, but this explanation 

 Wegener rejects, because to him sial can not sink into sima. The 

 chief geologist of Argentina, Doctor Keidel, has pointed out the 

 structural, stratigraphic, and faunal similarities between the Cape 

 Mountains and the Sierras of Buenos Aires, which in turn are 

 continued into the pre-cordilleras of northwestern Argentina, fur- 

 nishing Wegener with what he regards as striking evidence for 



^ H. S. Washington. Comagmatic Regions an^ the Wegpner Hypothesis. Journ. Wash, 

 Aead. Sci., vol. 13 (1923), pp. 339-347, 



