328 G. H. CHADWICK STRATIGRAPHY OF XEW YORK CLINTON 



Pagp 



Classitieation aiul faunas 359 



Conclusion 365 



Faleontologic summary 366 



Important papers 367 



Historical Ixtroductiox 



The "Clinton group"" of western New York has been supposedly a well 

 kno^ni formation. Hall (2)^, in 1843, described the section on the Gen- 

 esee Eiver at Rochester, whose various subdivisions of shale and limestone 

 he believed he had correctly traced eastward to the limit of his district 

 (namely, Eed Creek), and he affirmed the stratigraphic equivalence of 

 five of these to the series of sandy shales at Clinton, in central Xew York, 

 descril^ed in the preceding year by his colleague on the Survey, Yan- 

 uxem (1). Hall also followed the same group of strata westward to the 

 Xiagara River, where he correctly noted that the ''Clinton"' portion had 

 diminished in thickness by the nearly total loss of its shale members, thus 

 becoming a continuous massive limestone. 



It should be recalled that two of the sections just mentioned, namely, 

 the Genesee gorge at Rochester and the Xiagara gorge above Lewiston, 

 are the only complete expe-sures of the group in Xew York State (9 : 

 9-10), and that it would be difficult, if not impossible, to find any errors 

 in HalFs work from a surface examination alone. Xo criticism can there- 

 fore be made of his work or of those who have builded on it, though his 

 correlations are now found to be partly in error. 



The section of the so-called Clinton at Rochester, long taken as the 

 standard for comparison with other regions, is given below, together with 

 the names used by Hall (3), those applied by Hartnagel (8) in 1907 on 

 the basis of HalFs correlations, and the revised names, the necessity for 

 which is brought out in the sequel. This section now proves to be far 

 from a complete section of the Xew York Clinton, since several impor- 

 tant members are entirely missing. It is as follows, every inch being 

 accessible : 



- The numbers in parenthesis refer to the list of works at the end of this paper. 



