3 .6 



University of California. 



[Vol.. i. 



—the one progressive and the other conservative, the one tending to 

 changes, the other to stability, — is more or less subject to this law 

 of cyclical movement. Laws and forces, indeed, are uniform, but 

 phenomena everywhere and in every department are more or less 

 paroxysmal or catastrophic; though not catastrophic in the old sense 

 of being not subject to law. 



Thus, the fundamental idea underlying geological reasoning was 

 first catastrophism, then uniformitarianism, and now evolutionism. 

 But evolution moves not at uniform rate, but by cycles as explained 

 above. 



How Far May Divisions Be Made General. — Now the important 

 practical question in regard to these revolutionary changes — which 

 all must admit for special localities — is: How far are they, or at 

 least some of them, general? How far may they, or any of them, 

 be used to determine the divisions and subdivisions of geological 

 history of the whole earth? This, as I understand it is the question 

 under discussion. 



Until recently, perhaps under the still lingering influence of the 

 old catastrophism, the prevalent idea was that all these great 

 changes marked by unconformity and concurrent changes in organic 

 forms were general. Under this idea European standards of classi- 

 fication have been used as a procrustean bed to which all others 

 must conform, even in detail. This has been found difficult for our 

 American rocks, and impossible for those of India, Australia, and 

 South Africa. Therefore the tendency of the present time among 

 most advanced geologists is strongly toward a rejection of all gen- 

 eral divisions — to hold that all such changes are local and therefore 

 all divisions of record and of time, both primary and secondary, 

 and therefore all classifications must also be local. But again the 

 danger is that by revulsion this tendency also may go too far. It 

 is against this that I would raise a note of warning. 



If, indeed, the earth has developed as a whole, as evolutionism 

 would seem to require, then we ought to expect that amid many 

 smaller and more local changes there must have been some greatest 

 revolutions which have in some way either directly or indirectly 

 affected the whole earth, and which therefore may be used to form 

 the basis of the primary divisions of time. In the gradual changes 



