54 



Mr HOPKINS, ON RESEARCHES IN PHYSICAL GEOLOGY. 



line cdgh, supposed to be originally horizontal, indicates the faults 

 along DE and FG. We may easily conceive, however, a further modi- 

 Hcation of the phenomena from any irregularity in the action of the 

 elevating force, or in the resistance opposed to it, in adjoining portions 

 of the mass on opposite sides of any one of the incomplete transverse 



-4=^ 



fissures, similar to that which we have assumed to produce the faults 

 'DE, FG, at complete fissures ; for if this inequality of action on two such 

 ]}ortions of the mass be suflScient, it may evidently convert the incomplete 

 fissure into a complete one, provided the fissure extend near enough to the 

 surface to weaken the mass so much as to render it unable to counteract 

 the tendency of this unequal action, to give a greater elevation to the 

 portion on one side of the fissure than to that on the other. In such 

 ease a fault would almost necessarily be produced, but probably smaller 

 than that • which would be produced by the same cause at a complete 

 fissure. In either case, however, the fault may of course be of any 

 magnitude, depending on the intensity of the action producing it. 



If then we conceive the phenomena represented in the preceding 

 diagram to be thus modified, and the superficial elevations to have been 

 partially removed by denudation, the actual phenomena may be repre- 

 .sented as in the annexed .section. The broken line abcdefghi is as 



before, supposed to have been originally continuous and horizontal, or 



