STRATIGRAPHIC TAXONOMY 583 



Spergen, disregarded the boundaries of the faunal and lithologieal 

 provinces which prevailed during the ^Yaverlyan and spread with sur- 

 prising uniformity of expression from Missouri to Alabama and thence 

 northeastward in the Allegheny basin to west Virginia and perhaps to 

 Maryland. There was a change, also, in the northward extent of the 

 seas, none of the Tennessean stages reaching as far in that direction 

 as did certain Waverlyan formations. In short, a new set of conditions 

 was introduced in southeastern ^orth America with the Warsaw that 

 thereafter prevailed — with minor oscillations and tilting — to the close 

 of the Chesterian. 



CONSISTENCY OF METHOD IN DRAWING STRATIGRAPHIC BOUNDARIES 



Discussion. — The method of dividing geologic time has varied largely 

 according to the information and individual opinions of authors. Doubt- 

 less this is as it should be, for it would be a sad condition indeed if the 

 science of geology, with special reference to its taxonomic aspects, should 

 ever become so crystallized and fossilized that any scheme of classifica- 

 tion, however w^ell it may satisfy contemporaneous knowledge, were ac- 

 cepted as final. Fixity in method is death to progress, and, to say the 

 least, it is presumptuous to even hope that any one has said or ever will 

 say the last word on a scientific subject. 



But there is one feature of method that may be fixed without detri- 

 ment to science, namely, consistency in application. Of course, the suc- 

 cess of our endeavor to be consistent depends largely on the state of our 

 information. To that extent therefore it is just as liable to failure as 

 any other feature of method. But it fails only in details, which can be 

 corrected from time to time. Consistency therefore is a fundamental 

 factor that can stand whatever happens to the scheme temporarily 

 adopted. 



In the old classifications u.ndue prominence and rank was given to the 

 younger formations. This is because they cover wider areas, are more 

 commonly accessible, and contain a larger number and more beautifully 

 presented fossils than the older formations. Their fossils also were more 

 readily comparable with living organisms, while the relative strangeness 

 of the Paleozoic species naturally delayed the full recognition of their 

 geologic significance. Moreover, most of the large cities of Europe are 

 situated on Cenozoic and Cretaceous deposits, a circumstance that obvi- 

 ously contributed to their early investigation. As for the Triassic and 

 Jurassic, these like the overlying Cretaceous and Tertiary formations, are 

 well developed and highly fossiliferous in the Alpine regions of Europe, 



