1819.] Greenough on the First Principles of Geology. 459 



the whole globe of the earth. Our author controverts this 

 doctrine ; and it must be admitted that it stands upon very slight 

 evidence ; but I conceive that the assertion that formations are 

 universal means nothing more than that rocks occur in the some 

 order in all countries. That certain rocks are always nearest 

 the centre of the earth (in position), and certain rocks always 

 nearest the surface. Now the facts brought forward by our 

 author to controvert this opinion prove only that certain mem- 

 bers of the series are wanting; in different countries — a fact 

 which has been universally admitted ; but I do not see how this 

 can overturn the opinion, that rocks in every country affect a 

 particular order of arrangement. But the discussion of this 

 point comes more naturally under Essay V. which is entitled 



On the Order of Succession in Rocks. 



Our author in this essay controverts the Wernerian doctrine, 

 that rocks follow a determinate order, and seems to affirm Uiat 

 the order is perfectly capricious, and that from the arrangement 

 of rocks in one country, we can draw no inference with respect 

 to their arrangement in any other country, if there be no regu- 

 larity in the arrangement of rocks ; if they follow no particular 

 order ; if we can form no notion from the rocks which we 

 observe, whether any particular rock is likely to occur or not, 

 then the science of mining is founded upon no legitimate data, 

 and there can be no difference between the chance of success 

 when the most skilful and the most ignorant man are sent to 

 survey a country. A little consideration I should think must be 

 sufficient to satisfy our author that he has carried his scepticism 

 on this subject too far ; and that while anxious only to get rid 

 of the weak and rotten parts of the structure, he has in reality 

 demolished the whole science of geology ; for if there be no 

 regularity in the position of rocks ; if everv thing in the structure 

 of the earth is perpetually varying in the most capricious manner, 

 then geology can have no foundation whatever ; we can acquire 

 no general knowledge from an examination of the structure of 

 the globe, and the science must be considered as on a level with 

 astrology and necromancy. Would our author expect to meet 

 with beds of coal in a country composed of granite or mica slate? 

 Would he expect to meet with granite in a coal country ? Would 

 he search for mines of tin among rocks composed of shell lime- 

 stone ? If he found blende, would he not be induced to look for 

 accompanying galena? These, and many other examples, which 

 will immediately occur to every one conversant with the subject, 

 are sufficient to show us that the position of rocks is not quite so 

 capricious as our author supposes ; that certain substances have 

 a tendency to associate together, and that mining and surveying 

 are not without their laws and their rules. 



It may be very true that Werner generalized too rapidly; that 

 Saxony and Bohemia were too small a portion of the earth to 



