THE MINING AND QUARRY INDUSTRY I9I4 47 



of the Medina formation, near the top of the latter. This forma- 

 tion outcrops in a belt along the south shore of Lake Ontario and 

 consists mainly of shale with sandstones in the upper part, with an 

 aggregate thickness of about 1200 feet. It extends along the lake 

 shore from the Niagara river to Oswego county, and continues 

 eastward for some distance beyond the limits of this county. The 

 strata have been little disturbed or changed since their uplift. They 

 dip slightly toward the south or southeast, the average inclination 

 being about 50 feet to the mile. The dip together with the rising 

 elevation toward the south soon brings the strata under a con- 

 siderable cover which increases progressively with the distance from 

 the outcrop. The important gas pools of Erie and Genesee coun- 

 ties occur in the Medina at depths of from 1200 to 1800 feet; those 

 in the southern part of Erie county being the deepest. The lake 

 shore gas belt of Chautauqua county also derives its main supply 

 from the Medina which is encountered at depths of 1900-2300 feet. 

 The deepest explorations have been in northern Cattaraugus county, 

 where gas sands supposedly belonging to the Medina have been 

 encountered at 2500-3300 feet. 



Next to the Medina, the most important horizon is in the 

 Chemung sandstones at the top of the Devonic, the same strata that 

 yield the petroleum production of New York. The wells are from 

 600 to 1800 feet deep and were primarily drilled for oil, but the 

 gas is an important subsidiary product that is utilized in part for 

 pumping the wells. The excess is piped to the communities in the 

 district and as far as Buffalo. 



The Trenton limestone affords a small supply of gas which is 

 developed at Pulaski and Sandy Creek, Oswego county, at the east 

 end of Lake Ontario and at Baldwinsville, Onondaga county. At the 

 localities first named the wells are 1200-1500 feet deep and at 

 Baldwinsville 2400 feet. 



PETROLEUM 



The oil industry, which is confined to a small area in the. south- 

 western part of the State, has not been attended by any notable dis- 

 coveries or new developments during the past year. The produc- 

 tion, however, was of the usual proportions, as in fact it has changed 

 very little within the last quarter of a century. The maintenance 

 of the yield may be said to be the most remarkable feature of the 

 local industry, contrasting in that respect with many fields which 

 have had a much larger initial production. Tt is largely the result 

 of a policy of conservation and economy that has been pursued by 



