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CHAPTER IV. 



ATTEMPTS TO DISCOVER GENERAL LAWS IN 

 GEOLOGY. 



Sect. 1. General Geological Phenomena. 



BESIDES thus noticing such features in the 

 rocks of each country as were necessary to the 

 identification of the strata, geologists have had many 

 other phenomena of the earth's surface and mate- 

 rials presented to their notice ; and these they have, 

 to a certain extent, attempted to generalize, so as 

 to obtain on this subject what we have elsewhere 

 termed the laws of phenomena, which are the best 

 materials for physical theory. Without dwelling 

 long upon these, we may briefly note some of the 

 most obvious. Thus it has been observed that 

 mountain-ranges often consist of a ridge of subja- 

 cent rock, on which lie, on each side, strata sloping 

 from the ridge. Such a ridge is an Anticlinal Line, 

 a Mineralogical Axis. The sloping strata present 

 their Escarpments, or steep edges, to this axis. 

 Again, in mining countries, the Veins which contain 

 the ore are usually a system of parallel and nearly 

 vertical partitions in the rock ; and these are, in 

 very many cases, intersected by another system of 

 veins parallel to each other, and nearly perpendi- 

 cular to the former. Rocky regions are often inter- 



