6 



NEW YORK STATE MUSEUM 



FORMATIONS 



The rock formations here represented as units of sedimentation 

 may be grouped in broader divisions in the manner following : 



Neo- 

 devonic 



Meso- 

 devonic 



Ckautauquan group 



Senecan group 



Erian group 



Paleo- j TJlst erian group 

 devonic { Oriskanian group 

 Siluric ^1 



or y Cayugan group 

 Ontario J 



Chemung beds 

 1 Ithaca beds 



Portage beds 



Genesee beds 

 Tully limestone 



Hamilton beds 



Marcel lus beds 



Onondaga beds 

 Oriskany beds 

 f Cobleskill beds 



Salina beds 



Prattsburg 

 ( West hill 

 "j Grimes 

 f Hatch 

 I Rhinestreet 

 J Cashaqua 



Parrish (lentil in 

 Cashaqua) . 



Middlesex 

 f Standi sh 

 J West river 

 ) Genundewa 

 ( Genesee 



Tully 

 f Moscow 



Menteth (lentil in 

 J Moscow) 

 1 Tichenor 

 I Canandaigua 

 [_ Skaneateles 

 f Cardiff 

 < 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 ap- 

 pended, by slightly undulating lines traversing the region in a 

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

 bound the palpable outcrops over a region which before becoming 

 enveloped in the drift was not deeply channeled and by the 

 rigidity of its rocks was able to resist the erosion which 

 farther south has broken up the softer formations into projections 

 and outliers. 



Camillus shale 



The lowesi formation in the rock series and northernmosl on 

 the Canandaigua sheet is that subdivision of the Salina group of 

 formations which eonsisis of soft gypseous shale or plaster rock, 



