u 



Report op the State Geologist. 



which tlie precise position of the Portage sandstones is shown and their exact 

 relation to the faunas of the Portage and Chemnng group determined. These 

 sandstones lie at an elevation of 600 feet above the base of the Portage 

 formation. A few feet below them is a bed of shales in which are found 

 characteristic species of the peculiar and distinctive Portage fauna. Between 

 this layer, however, and the sandstones themselves is a thin stratum bearing a 

 small fauna unlike anything occurring in the normal Portage fauna. This 

 stratum contains brachiopods (Liorhyiwhus, Atr-ypa reticularis, ProducteUa, 

 etc), which indicate an encroaching fauna, not distinctively Chemung, but 

 more closely allied to the Ithaca fauna of the regions east of Seneca lake. 



It is further shown that the true Chemung fauna with Ilydnoceras 

 fiiherosum and characteristic brachiopods, is well developed within 100 feet 

 above these Portage sandstones, the intervening rocks not being clearly 

 exposed in this section, but apparently consisting of barren sandy shales. 

 The vertical distance from the base of the Portage group to the first pro- 

 nounced development of a Chemung fauna, in this section, is less than 700 

 feet. This is a considerably less thickness than is commonly accredited to this 

 formation, and much less than that which exists in the typical section on the 

 Genesee river at, and below, Portage ville, but the former has been measured 

 with much care. With these data in hand the author has traced the heavy 

 bedded Portage sandstones eastward to Seneca lake and westward to Lake 

 Erie. 



The Economic Geology of Onondaga County, N. Y. 



By D. D. Luther. 



In this paper the rock formations are discussed in their proper order of 

 succession, and while attention is given to the geologic character and dis- 

 tribution of each, many facts of interest are brought out, and the especial 

 value of the report consists in its exhaustive treatment of the most 

 important economic products of this county, viz. : Salt, soda-ash, gypsum, 

 hydraulic cement and quarry stone. 



Following a brief description of the somewhat peculiar topography of the 

 region, the shales <>f the Clinton group, the lowest formation represented, are 

 described. These outcrops are in the low lands of the northern part of the 

 county, and have shown no contact with the overlying Niagara limestone, 

 the Niagara group is very obscurely developed through the same region east- 



