STANDARD SECTIONS 1127 



some parts of which spread widely over the earth, and, with ele- 

 ments derived from other sources, constituted the local Middle De- 

 vonic faunas of eastern North America. (Grahau and Sherzer-2oa.) 



Standard or Type Sections. In general the first section studied 

 is taken as the type section for the country. Often it is not the 

 most complete nor the most perfect section, as in the case of the 

 Devonic section of southern England (Devonshire), which is less 

 perfect than that of the Rhine region ; or the Cretacic section of 

 Colorado and Montana, which is less complete than that of Texas 

 and Mexico. In such cases it not infrequently happens that, by a 

 process of natural selection, the poorer section is gradually re- 

 placed by the better, as in the case of the Rhenish Devonic, which 

 is now more frequently used for comparison, or the Cambric of 

 Scandinavia, which is more satisfactory than that of Wales. In 

 America the type section for the Palaeozoic formations is found in 

 the State of New York. This not only was the first section thor- 

 oughly studied in this country, but, what is more significant, it 

 turned out to be in many respects the most complete and most rep- 

 resentative of all American Palaeozoic sections. So truly repre- 

 sentative is this section that, "... while other classifications 

 proposed for these rocks, contemporaneously or subsequently, have 

 fallen to the ground, it has withstood all the attacks of time." 

 (Clarke-ii.) 



Not a little did the detailed palseontologic work carried on by 

 the State Survey of New York contribute to this prominence of the 

 New York Section. No other American region has had the organic 

 remains of its formations so fully investigated and descriptions and 

 illustrations of them published in such a complete manner. This 

 thoroughness, for which in a large measure James Hall was re- 

 sponsible, has forever made the New York column the foundation 

 on which all other work on Palaeozoic Stratigraphy of America 

 must be based. 



In spite of this fact, however, the relationships between the 

 various local sections of the State of New York have not yet been 

 fully ascertained, and each year facts are discovered which de- 

 mand a modification, in details, of these standard sections. 



Nor is the New York column as a whole complete and without 

 flaws. Undoubted Middle Cambric appears to be but slightly de- 

 veloped in the state, while the Lower and Upper Cambric also are 

 not fully represented, so far as the sections have been studied. 

 Hence the American type sections for these formations are ob- 

 tained from other regions : that for the Lower Cambric from north- 

 western Vermont and that for the Middle Cambric in the Acadian 



