Luther — Economic Geology of Onondaga County. 



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Clinton Shales. 



The lowest sedimentary rock formation exposed in this county is the 

 Clinton shales of the Niagara period. These are the bed rock underlying I lie 

 north part of the towns of Cicero, Clay and Lysander. This territory has 

 an average elevation of perhaps a little below 4(H) feet A. T. The surface 

 is gently undulating and the soil is generally sandy or gravelly. The streams 

 are all very sluggish and do not usually cut down to the rocks; hence 

 exposures are very rare. 



In the vicinity of the village of Brewerton, at the foot of Oneida lake, 

 the covering of drift is quite thin, and the rock is frequently uncovered by 

 the grading of the highways and in digging cellars. The rock is nearly all a 

 soft olive green shale, quite light colored when first exposed but, owing to 

 the iron it contains, it rapidly becomes a dark rusty brown. Some thin layers 

 occur, composed largely of fine grains of iron. They oxidize rapidly on 

 exposure and crumble into dust. 



The Disciples church, in the village of Brewerton, stands on a knoll about 

 ten feet high, composed of the Clinton shales, which are exposed near the 

 sidew alk in front. Forty or fifty rods south from the station of the Ontario 

 and Western railroad, the highway cuts through a similar knoll, exposing four 

 or five feet of the shales, and other similar small exposures occur toward the 

 east along the shores of Oneida lake, and toward the west near the Oneida 

 river, though they are not sufficiently dispersed, nor of such a character as to 

 permit the accurate measurement of the thickness of that part of the Clinton 

 group included in the surface rocks of this county. 



The exposures at Brewerton are fifteen to twenty feet above the Oneida 

 liver, and three miles from the line of the outcrop of Niagara limestone, and 

 the elevation is very nearly the same, so that the thickness of the intervening 

 beds of shale can only be determined by ascertaining the amount of dip, which 

 can not be done by direct measurement on account of the lack of good expo- 

 sures. It is impossible, for the same reason, to locate the contact line betw een 

 the Clinton and the overlying Niagara shale. 



Niagara Limestone. 



The limestones of the Niagara period are exposed at several places along 

 a line from the northwest corner of the county to Bridgeport, across a section 

 of country which has an elevation of -'575 feet at the east line of the county, 

 and rarely rises above 400 feet A. T., except in the northwestern part of the 

 town of Lysander. 1 neir position is sometimes indicated by a low ridge, but 



