3. CENTRE TOWNSHIP, F 2 . 191 



any great thickness. Some years ago an attempt was made 

 to burn some of them for lime but it proved a failure. The 

 lime would not slake. As will be mentioned in the report 

 on Madison township similar beds there yield lime of fair 

 quality. It might be worth the experiment to try if these 

 limestones at Bloomh'eld would yield hydraulic cement. I 

 have also seen the Marcellus limestone at its outcrop be- 

 tween Bloomfield and Clark's mill, where it may again be 

 taken as evidence against the presence of a thick bed of. 

 ore. A partial analyses of this limestone will be found in 

 that part of the report relating to Madison township. 



The Marcellus iron ore bed. 



This is the bed from which most of the iron ore raised in 

 the township has been taken. Its outcrop may be readily 

 traced upon the geological map, as it coincides with the 

 line between the Marcellus limestone and the Marcellus 

 black shale. As will be seen at a glance its course is ex- 

 ceedingly irregular, and the tracing of it through the town- 

 ship was a task of some difficulty. The complication of 

 the structure of Centre township will be evident to any one 

 who carefully examines the maps and sections given with 

 this report. Following the ridges of sand-rock across a 

 county may seem, at first sight, a very unprofitable task, 

 but in no other way was it possible to determine the ground 

 in which this bed of iron ore could or could not exist. 



This ore is often called in the district the limestone ore, 

 to distinguish it from the other ores in the county. The 

 name is not strictly true in the sense intended, and yet it 

 is true in another. It does not lie in or on the Lewistown 

 limestone — the great limestone of the county — but it does 

 lie in contact with a bed of impure greenish limestone or 

 calcareous shale which has been erroneously considered the 

 equivalent of the Corniferous limestone of New York. 

 This is never far from the great limestone, its proper hori- 

 zon being about 50 feet above the Oriskany sandstone. 

 Hence the upper surface of the sand-rock when it can be 

 discovered, is an unfailing guide to the position of the ore. 



The first outcrop line of the Marcellus hematite enters 



