GEOLOGY OF THE GENEVA-OVID QUADRANGLES 



31 



some parts bear a close resemblance to the olive and blue shales 

 of the lower beds of that formation. 



The increase in the proportion of sand in the sedimentation 

 toward the east so noticeable in the upper beds of the Cashaqua is 

 also apparent in this formation though to a less degree. 



The gradual change in the character of the fauna in that di- 

 rection is, however, still more marked. 



In the Genesee river section no fossils but those of the normal 

 Portage or Naples fauna are found in these beds. At Naples near 

 the top a thin seam shows remains of brachiopods broken and 

 crushed beyond recognition but they do not occur below that hor- 

 izon, while in this region vertical sections show frequent alterations 

 of the normal Naples fauna and the brachiopodous Ithaca fauna of 

 central New York; indication of oscillation between them in which 

 the latter acquires predominance in the Cayuga lake valley but not 

 to the exclusion of the former. 



Although this formation covers a large area on this quadrangle 

 there are few satisfactory exposures and none that are favorable 

 for an exhaustive collection of its fossils. 



The following species have been obtained from the Hatch shale 

 and flags in the Seneca lake valley, mainly from the region south 

 of this quadrangle : 



Manticoceras patersoni (Hall) 

 Probeloceras lutheri Clarke 

 Tornoceras uniangulare (Conrad) 

 Orthoceras bebryx Hall 

 Bactrites 



Styliolina fissurella Hall 



Bellerophon koeneni Clarke 



Loxonema noe Clarke 



Spirifer laevis Hall 



Sp. mucronatus var. posterns Hall 



& Clarke 

 Sp. subumbona Hall 

 Productella speciosa Hall 

 Schizophoria impressa (Hall) 

 Atrypa reticularis Linne 



Centronella julia A. Winchell 

 Chonetes scitulus Hall 

 C. lepidus Hall 

 Productella spinulicosta Hall 

 Strophalosia truncata Hall 

 Leptostrophia mucronata (Van- 

 uxem ) 



Buchiola retrostriata (v. Buck) 

 Lingula spatulata Vanuxem 

 Pterochaenia fragilis (Hall) 

 Paracardium doris Hall 

 Lunulicardium ornatum Hall 

 Honeoyea erinacea Clarke 

 Paleoneilo sp. 

 Cladochonus 



Grimes sandstone 



This is a well defined arenaceous band easily recognized in the 

 region west of these quadrangles as far as the Genesee river. It is 

 made distinctive in the Naples and Dansville valleys by containing 

 the lowest brachiopod faunule in the Portage section of that region. 



