STRATIGRAPHIC TAXONOMY 609 



column, doubtless, are more fully developed in the Cordilleran troughs 

 of western America, but, taken as a whole, neither the Cordilleran nor 

 any other area offers so complete and clear a record of Paleozoic history. 

 Certainly no European area is comparable in these respects, and none 

 anywhere is, therefore, so well fitted to furnish the world standard. 



In this connection I may mention the Baltic section, which is generally 

 referred to as a very complete record of pre-Devonian Paleozoic deposi- 

 tional and faunal history. In fact, however, it is far from being so. 

 Whole chapters are missing, and it is greatly inferior to the Appalachian 

 record. Compared with the composite pre-Devonian section as now 

 worked out in southeastern North America the Baltic sequence may be 

 described as consisting of epitomized quotations from the sedimentary 

 record of the Arctic and N'orth Atlantic seas. Though beautifully punc- 

 tuated with well preserved fossil faunas and worked out in great detail 

 by the Swedish and Eussian geologists, the Baltic record yet presents 

 only one-sided, biased testimony, rendering it unfit to rank as a standard 

 for the world. Contrasted with the corresponding American sedimentary 

 record, the Baltic section is inferior in every respect, and greatly so in 

 most. In view of these facts, the recent proposal by Moberg to revive 

 the Murchisonian conception of the Silurian ; that is, a Silurian embrac- 

 ing all the rocks from the base of the Cambrian to the base of the De- 

 vonian, seems too much like wiping out the results of fifty years of work 

 in stratigraphy to be entertained for a moment. 



GENERALIZED ^TATEMEXT OE PROPOi^ED CHANGES 



In constructing the new classification sentiment has played but a small 

 part. My endeavor has been to apply the adopted principles in rigorous 

 and consistent accord with my conception of the facts. So far as my 

 information extends, the result is a fair test of the application of dias- 

 trophism in determining the essential contemporaneity of geologic events 

 and of the claims of those who believe that the criteria which imply 

 crustal movements offer the only reliable, or, as Chamberlin would ex- 

 press it, the "ultimate," basis of stratigraphic classification. 



Of the new features of the proposed classification the most conspicuous, 

 perhaps, is the great expansion of the pre-Devonian parts of the stra- 

 tigraphic column. Many new units, ranging in rank from systems or 

 periods down to formations or ages, are intercalated in the time scale. 

 A part of this expansion is by discovery of formations hitherto over- 

 looked ; but the greater part is by placing units either above or beneath 

 those of the current standard with which they have till now been corre- 

 lated. Most of the latter changes are based on positive stratigraphic 



