322 SEE-THE CAUSE OF EARTHQUAKES. [Ociober 19 



shores, while the account given of cross ranges and parallel ranges 

 standing in isolation is unsatisfactory, it must be admitted that the 

 theory itself is not well founded. 



The assumption that since the continents began to rise from the 

 oceans the earth has shrunk enough to produce great wrinkles in 

 the crust comparable with our high mountains is undeniably a violent 

 hypothesis. For in the writer's paper on the rigidity of the heavenly 

 bodies (A. N., 4104), it is shown that no circulation of currents 

 within the earth has been possible since the globe became encrusted. 

 If there are no currents within, the propagation of heat outward 

 could take place only by conduction; and from Fourier's analytical 

 theory of heat we know that the loss of heat would be extremely 

 slow, and confined almost wholly to a shallow layer near the surface. 

 Indeed it seems probable that the shrinkage of the entire globe is 

 barely comparable to the secular contraction of the cooling crust 

 alone. The approximate accuracy of this view is confirmed by the 

 fact that the crust has not cracked open by pulling apart, as it 

 would do if the crust shrank much more rapidly than the globe as 

 a whole. The fact that the interior of the globe lost very little 

 heat, while the crust cooled all the time, would lead one to think that 

 so far from wrinkling by contraction, the crust ought to have 

 cracked open by the shrinkage of the shell over a nearly unyielding 

 nucleus ; but no doubt the process was too slow and the rocks too 

 plastic to give rise to actual rupture of the earth's crust. 



Moreover, if the globe shrank, it is inconceivable that this shrink- 

 age could fail to be fairly uniform in the different equal areas of the 

 surface, and thus we should expect the resulting wrinkles to be 

 distributed over the globe with moderate equality and uniformity. 

 Instead of this, we find the mountains, heretofore assumed to be 

 wrinkles, bunched into congested systems, and almost always paral- 

 lel to the seashore, and larger in proportion to the depth of the 

 adjacent ocean. Is it therefore at all credible that the mountains 

 have really been formed by the shrinkage of the earth ? Would it be 

 going too far to say that the whole theory of secular contraction 

 as applied to our encrusted planet is a misconception dating from 

 a time when currents were supposed to circulate freely throughout 

 a liquid globe ? 



