95 



3 THE ARGUMENT FROM STRATIGRAPHY 



The fact that the faunas of the Manlius limestone and the Ron- 

 dout waterlimes are not, in this discussion, considered a part of the 

 fauna of the Helderbergian has already been stated. The distinctive 

 differences in these faunas are briefly noted in the following chapter. 



In eastern central New York there is no interruption in the 

 stratigraphic succession from the Manlius limestone upward. The 

 heavy layers of this formation are generally capped by a Stromatopora 

 limestone. In the westward extension of the Helderbergian, the 

 Coeymans and New Scotland limestones gradually lose their individu- 

 ality. In the rec >rds of salt, gas and artesian wells throughout the 

 district west of Cayuga lake the strata referred to the Lower Helder. 

 berg, often of considerable thickness, present nothing of the true 

 Helderbergian. These vague and indeterminate assignments cover for 

 the most part the blue limestone, generally quite pure and often 



