NEW YORK STATE MUSEUM 



FORMATIONS 



The rock formations here represented as units of sedimentation 

 may be grouped in broader divisions in the manner following : 



' Chautauquan group 



Neo- 

 devonic 



Senecan group 



Chemung beds 

 Ithaca beds 



Portage beds 



< 



devoniciErian group 



Paleo- j Ulsterian group 

 devonic ] Oriskanian group 

 Siluric ^ 



or y Cayugan group 

 Ontario J 



Genesee beds 

 ^Tully limestone 



Hamilton beds 



Marcellus beds 



Onondaga beds 

 Oriskany beds 

 Cobleskill beds 



Salina beds 



Pratt sburg 

 f West hill 

 ] Grimes 

 r Hatch 



Rhinestreet 



Cashaqua 

 Parrish (lentil in 

 Cashaqua) 



Middlesex 

 f Standish 

 j West river 

 ] Genundewa 

 ( Genesee 



Tully 

 r Moscow 



Menteth (lentil in 

 Moscow) 



Tichenor 



Canandaigua 



Skaneateles 

 f Cardiff 

 -I Stafford 

 [ Marcellus 



Onondaga 



Oriskany 



Cobleskill 

 \ Bertie 

 } Camillus 



SILURIC 



General observations. All these formations are so deeply 



buried under a continuous drift mantle that their variations can 



be studied only at a disadvantage. We have indicated the contact 



lines of these as well as the lower Devonic formations as a])- 



pended, by slightly undulating lines traversing the region in a 



nearly east and Avest direction. It is our belief that such lines 



bound the palpable outcrops over a region which befor*e becoming 



enveloped in the drift was not deeply channeled and by the 



rigidity of its rocks was able to resist the erosion which 



further south has broken up the softer formations into projections 



and outliers. 



Camillus shale 



The lowest formation in the rock series and northernmost on 



the Canandaigua sheet is that subdivision of the Salina group of 



formations which consists of soft gypseous shale or plaster rock, 



