THE PENDULATION THEORY 



893 



more fully in his book, "Die Pendulations Theorie," fortifying it 

 by a wealth of illustrations furnished by the distribution of animals 

 and plants in both the present and past geologic periods. Simul- 

 taneously with Reibisch, the theory of polar migrations was formu- 

 lated by Dr. D. Kreichgauer (25), who approached the subject 

 from a purely geological point of view. He endeavored to explain 

 the changes of climate in past geological periods by a change in 

 the position of the earth's equator and therefore a shifting of the 

 north pole, which he thought had migrated 180° since Cambric 



Fig. 243. Map showing the hypothetical wanderings of the earth's North 

 Pole during the successive periods of its history. (After Kreich- 

 gauer.) 



time, having been at the beginning of that period where the south 

 pole is now. Kreichgauer 's map, showing the migration of the 

 poles, is here reproduced. (Fig. 243.) As Simroth points out, how- 

 ever, Kreichgauer did not consider the phenomenon of polar pen- 

 dulation. 



The theory of polar pendulation, as formulated by Reibisch 

 (34) and developed by Simroth (37), postulates the existence of 

 two "oscillation poles" (Schzvingpolc) in addition to the two ro- 

 tation poles. These oscillation poles lie in the region of modern 

 Equador, on the one hand, and of Sumatra, on the other. The 



