THE PENDULATION THEORY 897 



in the land, such as the Caspian and the Dead Sea, etc., He in the 

 North Atlantic quadrant, which also approaches the equator. It 

 should be noted, however, that the Marian depression with the 

 deepest submarine pit. the Xero deep, lies mostly north of the 

 equator and therefore in the opponent quadrant. However, its 

 proximity to the equator (less than 20° N.) is evident, and it may 

 be regarded as still retaining the characters acquired as it passed 

 under the equator. In like manner, the greater part of the African 

 rift valley lies in the south Atlantic-Indian quadrant, though again 

 within 20 degrees of the equator. 



Conversely, regions approaching the poles are regions of 

 shrinking land, and hence regions where mountain-making through 

 folding is marked. 



Ingenious and suggestive as this theory is, and much as it seems 

 to throw light on many geological as well as biological phenomena, 

 it is still too new and too little tested to receive more than re- 

 spectful attention. As a working hypothesis in the attempt to in- 

 terpret the history of the earth, it is likely to be of much value. 

 (See the application of this theory by Yokoyama to the interpreta- 

 tion of the Pleistocenic problem, given in Chapter II.) 



In this connection may also be mentioned the recent studies by 

 Eugenio Jacobitti (22), who, attacking the problem as a study in 

 geology, finds the wanderings of the poles to be of a more irregular 

 character, through the various geological periods, as illustrated in 

 the subjoined figures reproduced from his paper. (Figs. 246, 247.) 

 He also reconstructs a series of charts .showing the position of 

 the equator in the successive periods. All such reconstructions are, 

 of course, premature, and must be taken as suggestions rather than 

 as demonstrations. What is probably the most complete attempt at 

 restoration of the earth's surface during a period of different polar 

 location is that made by Koken (23a) for the Permic. His map 

 not only locates the poles but also the lands and seas of the period, 

 as well as the ocean currents, etc. See ante, page 536. 



It may again be remarked here, as was stated in Chapter 11, that 

 astronomers have generally looked with disfavor on such specula- 

 tions, though George Darwin concedes the possibility of the pole 

 having wandered some 10 or 15 degrees from its original position, 

 provided the degree of rigidity of the earth is not so great as to 

 be inconsistent with a periodic readjustment to a new form of 

 equilibrium. Sir William Thompson (Lord Kelvin), for one, 

 readily entertained the idea of such changes. He says : "We 

 may not merely admit, but assert as highly probable, that the axis 

 of maximum inertia and axis of rotation, always very near one an- 



