190 POPULATIONS OF THE SEA 



The rarity or absence of recognized contiguous shelf facies and 

 intermediate equivalents is a principal difficulty with acceptance 

 of the flysch facies as everywhere deep. Obviously there were 

 contiguous shallow waters, and, although it is a stock suggestion 

 that the flysch facies sediments have invariably been disconnected 

 during compressive deformation, it seems certain that some of the 

 equivocal flyschlike sediments will prove to be of an intermediate 

 nature. A comprehensive survey of an undeformed flysch basin is 

 badly needed. 



Polar and Crustal Drift 



To the paleobiogeographer polar wandering, continental drift, 

 or slippage of the earth's outer shell are simply ways of changing 

 the climatic zonation or of compressing or expanding biotic 

 gradients. His concern with such matters is whether or not the 

 paleobiogeographic evidence demands, is helped by, or is consistent 

 with such movements; and, if so, in what direction and to what 

 extent. 



To apply Occam's razor to the problem, he should first consider 

 whether observed distributions can be satisfactorily explained in 

 the present framework of the earth, then explore other possi- 

 bilities. I have done this elsewhere (Cloud, 1959b, pp. 946-948), 

 although in far less detail and range than is needed, and concluded 

 that the distribution of certain Paleozoic warm-water indicators 

 could be explained about equally well with the equator where it 

 now is, or through the poles. 



The concept of great polar (and equatorial) drift, however, has 

 been advocated on the basis of paleomagnetic data from the turn 

 of the century onward (e.g., Kreichgauer, 1902). A recent 

 variation (Fig. 11) is that of Runcorn (1959) and others, 

 whereby concurrent continental and polar drift is called upon to 

 explain separate paths of polar migration deduced from the data 

 of remanent magnetism on different continents. 



This is not the time or the place either to review the subject 

 exhaustively or to ignore it wholly.* I will conclude, therefore, by 



* An excellent recent review is that of Allan Cox and R. R. Doell, Review of 

 paleomagnetism. Geo/. Soc. Am. Bull., 71 (6), 645-768 (1960). 



