GEOLOGICAL POSITION AND GEOGRAPHICAL DISTRIBUTION 223 



alent of the Portage In the western part of the state. '^' The 

 number of quarries in this blue-stone district, in SulHvan, 

 Ulster, Greene, Albany and Schoharie counties is large and 

 can be increased indefinitely, as nearly the whole area 

 of the formation appears to be capable of producing stone 

 for flagging or for building. The difficulty of indicating 

 the division line between the Hamilton and the Oneonta 

 and the Hamilton and the Portage group of rocks makes it 

 impossible to refer to localities more particularly. The 

 quarries near Cooperstown, In the lake region, particularly 

 at Atwater, Trumansburgh, Watklns Glen and Penn Yan 

 belong to the Hamilton group. 



Portage Group 



As stated above, the limits of the Oneonta at the east 

 cannot be Indicated and the flag-stone beds of the Hudson 

 valley and of the eastern part of the state continue up Into 

 the Oneonta sandstone horizon. Many of the quarries are 

 In the latter formation. The more western and north-west- 

 ern and higher quarries are In It ; and some of the Chenango 

 county quarries also. 



The Portage rocks in the western part of the state have 

 been divided into shales at the base ; then shales and flag- 

 stones ; and the Portage sandstone at the top. In the last 

 division thick beds with little shale are marks of this hori- 

 zon. And the stone is generally fine-grained. The quarries 

 near Portage and near Warsaw are In it ; also the quarries 

 at Laona and Westfield in Chautauqua county. 



Although not of as great extent in its outcrop as the 

 Hamilton group the Portage rocks are developed to a thick- 

 ness of several hundreds of feet along the Genesee river at 

 Mount Morris and at Portage ; and form a belt having a 

 breadth of several miles through Tompkins, Schuyler, 

 Yates, Ontario and Livingston counties, and thence west to 



* Paleontology of New York, vol. v, part I. Lamellibranchiata II, pp. 517-8. 



5 



