228 Report of the State Geologist. 



area of central and western New York, that is profitably accessible f<>r com- 

 mercial purposes. 



In order to show the position of the Portage sandstones in the strata and 

 their relations t<> the geologic divisions above and below them, the rock 

 section in a typical valley of the " linger lake region " lying in the extreme 

 southern part of Ontario county, and in the central part of the New York 

 salt fields, the valley of Naples, is here given. 



The valley of Canandaigua lake extends about five miles beyond the 

 head of that lake m a southwesterly direction, to the southern boundary line 

 of the town of Naples, Ontario county. It has an average width of about one 

 mile. The sides are steep and high. Hatch hill on the east side rises to the 

 height of 1,041 feet above the lake level, and Pine hill at the south, and Hig h 

 point, one mile west of the valley, are each about two hundred feet higher. 



The floor of the valley for three and one-half miles from the lake is a low 

 alluvial plain, but at the south end there is an immense deposit of morainic 

 till, and the delta terrace at the mouth of Grimes gully, nearly 200 feet high, 

 projects half way across the valley. The village of Naples is situated at the 

 foot of this terrace. 



On the steep hillsides the soil, which is composed largely of the disinte- 

 grated shales, is thin, and loose fragments removed but slightly from their 

 original position in the harder sandy layers, abound everywhere. The dug- 

 ways ascending the hills diagonally, frequently afford long exposures of the 

 bed rock, but the best opportunities for examination of the rock strata are 

 presented in the ravines or gullies, of which there is a large number 

 debouching into the main valley. The largest of these is the Parrish gullv, 

 on the east side, about two miles south of the lake. An alluvial cone at the 

 mouth is about fiftv feet higher than the lake. Above the cone the bottom 

 and sides of the ravine present an interesting and accessible rock section 

 somewhat less than 600 feet high, that includes all of the strata of the Portage 

 group except some shale beds at the base. 



The Tannery gully, also on the east side, but near the south end of the 

 valley, exposes a continuous section 500 to 600 feet thick, beginning in the 

 middle Portage or Gardeau flags, and extending upward into the Chemung 

 sandstones. 



On the west side, the Grimes gully exposes about 40<"> feet of the upper 

 Portage and lower Chemung locks. The Portage sandstones are particularly 

 well displayed in this ravine and present abundant opportunity for the most 

 critical examination. 



