MOVEMENT IN THE CRUST OF THE EARTH 9 



this modulus is greatly accelerated at the critical point, we have 

 a law which will regiment the facts of geonomy as the facts of 

 astronomy are marshaled by the law of gravity. 



Under this theoretic law of the accelerated modulus of com- 

 pression at the critical point for different substances, subsidence 

 and upheaval are explained. The reassumption of constitutional 

 structure in crystallization and glassy lithification necessitates 

 expansion, and thus upheaval is explained. When lands rise and 

 are denuded, the process of relithification in the centrosphere con- 

 tinues upheaval and exposes the lands to further upheaval, and 

 this process goes on until an equilibrium is reached at the epoch 

 when the land is brought to the level of the sea by degradation. 

 On the other hand, as land is loaded the subjacent crust rocks 

 are brought within the zone of accelerated compression, and this 

 process continues while the loading continues until it is brought 

 to a close at the epoch when the land area from which the detritus 

 is taken is brought to the level of the sea and transportation 

 ended so that loading ceases. 



Universal contraction by cooling must still be postulated as 

 an agency for the destruction of equilibrium, or perhaps we may 

 find this agency in astronomical conditions ; but some such agency 

 is necessary for the continuation of the process. But the chang- 

 ing of material from the interior to the surface and the changing 

 of load from one district to another by transportation under the 

 law of the accelerated modulus of compression is the principal 

 agency of upheaval and subsidence. 



This doctrine was proposed several years ago by myself, but 



has received little attention except among a few geologists 



engaged in this branch of research ; from its reception by these 



gentlemen I am encouraged to repropound it. 



J. W. Powell. 



