RELATION OF BIOLOGY TO GEOLOGICAL INVESTIGATION. 321 



narrow limits. This, briefly, is my conception of the true character of 

 the only standard of correlation that may legitimately be used, because 

 it is the only one that agrees with a rational interpretation of natural 

 laws. 



It has, however, been the custom of a large proportion of geologists 

 to regard the geological scale as it lias been established in Europe as 

 the absolute standard for the whole earth. A necessary consequence 

 of this view is their assumption that the systems which physically con 

 stitute that scale, and at least most of the divisions of those systems, 

 may not oidy be recognized, but as clearly defined in all parts of the 

 earth as they are in Europe, if in those parts contemporaneous deposits 

 were made and still remain intact. 



While fully accepting the fact of the existence of a rational standard 

 of correlation and of its great practical value, it is my purpose to oppose 

 the idea of its absoluteness which is still entertained by many geolo- 

 gists, and which was formerly entertained by all. Before proceeding 

 with those remarks, however, it is desirable to inquire briefly as to the 

 origin of that idea and the probable reason of its survival, and to refer 

 to other ideas which were entertained by the early geologists but which 

 have long been abandoned. 



One of the abandoned ideas referred to relates to the recognition of 

 lithological identity as a criterion of correlation. This idea is indicated 

 in various ways by the writings of those early authors and to some 

 extent by their application of names to the divisions of the scale — such, 

 for example, as Old Eed Sandstone and New Red Sandstone* for the 

 Devonian and Triassic systems, respectively. Another relates to the 

 degree of consolidation or compactness that sedimentary rocks have 

 acquired, and still another to the degree of general disturbance which 

 they have suffered. As already stated, those pioneers regarded these 

 conditions as indicating relative age and also as being an aid to litho- 

 logical identification as a criterion of correlation. 



These ideas were abandoned because they were found to be untenable 

 even from the standpoint of their originators, and yet they are scarcely 

 less rational than is that which ascribes absoluteness to the European 

 scale as a standard of correlation. The only cause that I can suggest 

 for the survival of the latter idea while the former ideas have been 

 abandoned is a general conservative disinclination of the mind to adjust 

 itself to new methods of thought, especially if the old methods have 

 been rendered plausible by artificial adjustment to indisputable facts, 

 and are intricate by the complex nature of the subject. The idea of 

 the chronological value in the study of systematic geology of litholog- 

 ical character and conditions seems to have been abandoned not only 

 because it was fallacious but because the portion of the subject to 



* The Permian was by the early geologists sometimes included with the Triassic 

 under the name New Red Sandstone. 

 H. Mis. 114, pt. 2 21 



