1170 



NEW YORK STATE MUSEUM 



the Manlius becomes complicated with the Coeynians limestone, 

 the faunas of these two formations either mingling or alternately 

 recurring. 



Age of the shales below the Cobleskill at Schoharie 



The shales below the Cobleskill at Schoharie were desig- 

 nated as Clinton by Hall and now that we know that the Coble- 

 skill is above the Salina the age of these unfossiliferous shales 

 again comes into question. Mr Schuchert [p. 178] holds that 

 "on the basis of the adjoining sections, the age of these olive 

 green shales seems to be Lower Cobleskill." What appears to 

 be the chief argument, given for the determination of the age 

 of the shales as Lower Cobleskill is as follows [p. 176]. " In 

 Herkimer county the Clinton is not followed by the Magaran, 

 but at once by the Salina. Farther east the Clinton also fails, 

 and at Schoharie, after 19 feet of the pyritiferous shales, there 

 follow at once the Cobleskill, the Rondout, with the Coralline 

 fauna, the Upper Manlius, and then the Helderbergian. Here 

 the united thickness of the Cobleskill, Rondout and Upper 

 Manlius is 91 feet, while about Litchfield the same zones are 110 

 feet thick. Therefore, the pyritiferous shale of Schoharie can not 

 be the Clinton, but probably is the thinned eastern edge of the 

 lower part of the Cobleskill of the Litchfield section and not of 

 the true Waterlime or Bertie formation." Even if we grant the 

 thickness of the Cobleskill in Herkimer county as 30 feet, I am 

 unable to see how the shales at Schoharie can be the thinned 

 eastern edge of the lower part of the Cobleskill. If 19 feet 

 represented the total thickness of the shales at Schoharie, this 

 if added to the Manlius group of Schuchert would give about 

 the same thickness as in Herkimer county. But as a matter of 

 fact the shales below the Cobleskill at Schoharie have a greater 

 thickness than that given to the Cobleskill in Herkimer county. 

 The shales therefore can not represent the thinned eastern ex- 

 tension of the Cobleskill. Again in Schoharie county at Howes 

 Cave the thickness of these shales is about 40 feet, which if 

 added to the Manlius would give in Schoharie county a much 

 greater thickness than the Manlius of Herkimer county as 

 defined by Schuchert, thus showing more conclusively that the 



