88 TliAXSACTIONS OF THE AMERICAN INSTITUTE. 



eut upon the accumulation of sediments, and the causes are not to be 

 sought for in any special elevator}'^ movement. 



Now in order to arrive at any rational explanation of this pheno- 

 menon, and the causes producing it, we may refer to what is under- 

 stood as a well established law, dependent on the conditions of the 

 interior of our planet. It is well known that the crust of the earth, 

 the continents and the islands, are not stationarj^ : first, as I have 

 already stated, they are subject to abrasion and degradation from the 

 influence of the elements ; and second, it is known, by comparison 

 with the ocean level, that certain parts of continents along the coast 

 line are rising above, or becoming depressed below, the sea level. 

 Such a movement can only arise from the interior portions yielding 

 to the pressure from above ; and whether this yielding may be due to 

 partial or entire fluidity of the mass, from heat, it is not necessary 

 now to inquire. That oscillations of the surface have taken place in 

 modern times as well as in former geological periods, is well proven. 

 Admitting this condition of the interior, the transfer of material from 

 one part of the earth's crust to another will cause a disturbance of the 

 equilibrium of pressure, and a consequent change in the elevation of 

 some other part. At the same time, the transfer of material from one 

 part to another will likewise disturb the equilibrium of temperature ; 

 and we have both these forces operating at every change of condi- 

 tion or transfer of materials upon the earth's crust. ITow, whenever 

 materials are transported from the shore and spread over the bed 

 of an ocean as in the case of our geological formations, the first ten- 

 dency is to disturb the equilibrium of pressure, and the area of accu- 

 mulation would be gradually depressed ; but as these deposits accu- 

 mulated and the depression went on, they would at last be permeated 

 by the increasing temperature and finally brought to that degree when 

 expansion would take place, and the entire mass be finally elevated. 

 Or, to make myself better understood, we will assume that at the 

 depth of 1,000 feet there is a certain temperature, due to internal 

 heat. If then, by depressing the surface, or by any other means, we 

 are able to pile upon this 5,000 feet of new material, the internal 

 heat will gradually penetrate the mass until the equilibrium of tem- 

 perature is attained, and we shall have essentially the same degree of 

 heat at 1,000 feet below the new surface that we had at the original 

 point now 6,000 feet below. At the same time, this deeper point 

 will have acquired a higher temperature in proportion to its depth 

 beneath the surfoce. This accession of temperature will necessarily 



