THE EARLY DEVONIC OF NEW YORK 



The theme of this treatise bears upon one period only of our geologic 

 history. It is not to fight again the battles as to where the division line 

 between the great Siluric and Devon ic systems is to be drawn or as to 

 what constitute the early stages of the Devonic record. Such contentions 

 are effectively determined ; only an occasional shot is heard from some 

 dreamer who slept while the battle was on and wakes to find the field 

 taken and the issue determined. 



We here endeavor to portray and to bring into comparison with the 

 early Devonic of New York, faunas of like age from regions of eastern 

 Quebec, northern New Brunswick, northern and eastern Maine ; inciden- 

 tally other regions of smaller area and already closely studied — St Helen's 

 island at Montreal, Lake Memphremagog on the boundary of Vermont and 

 Quebec, northern New Hampshire and western Massachusetts — have been 

 brought within the scope of the work, so closely are all these regions knit 

 to New York and so important have been their contributions to its history. 



In New York the deposits constituting the earliest members of the 

 Devonic series are, at the bottom, i) the Helderbergian and, overlying, 

 2) the Oriskanian, There is a demonstrated gradation of the sediments 

 and the faunas of the lower into the higher, and those at the summit of the 

 Helderberg series — Port Ewen beds — carry so large a representation of 

 Oriskany species, as shown by recent analyses, that they may be wisely 

 regarded as indicating the passage of the earlier into the later fauna. 



The Helderbergian rocks (in the Helderberg mountain region compris- 

 ing the following divisions from below upward : i Coeymans limestone, 

 2 New Scotland limestone and shale, 3 Becraft limestone) enter New York 

 from the southeast along the New York-New Jersey line, and end north- 

 ward in an abrupt escarpment facing east and north in the southern angle 

 of the present Hudson and Mohawk rivers. Of this heavy sheet of calca- 

 reous strata there is no trace in New York east of the Hudson river save 

 two small synclinal outliers in Columbia county, Becraft mountain and Mt 



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