IRON ORES OF THE CLINTON FORMATION 53 



The deposition of the iron partly in the form of carbonate is 

 indicated by the fact that the fossil ores quite commonly show 

 a small percentage of this mineral. It is probable, however, that 

 the iron was mostly precipitated as the hydrated oxid. The 

 change from limonite to hematite took place subsequent to the 

 upraising of the beds under the influence of pressure from the 

 oxerlying strata. 



The New York Clinton beds, in common with those of Ohio, 

 Ontario and Wisconsin, were deposited along the northern 

 margin of the interior Mississippian sea, and the ferruginous 

 materials must have been derived largely from the wash of the 

 Precambric land mass on the north and northeast. The New 

 York section has its maximum development in the stretch from 

 Clinton to the west end of Oneida lake where there was ap- 

 parently an embayment curving around the southwestern border 

 of the Adirondacks. The present outcrop in this part is every- 

 where within 50 miles at most of the crystalline area. Farther 

 west the beds diminish gradually with the increase of distance 

 from the Adirondack highland, and in the extreme west the 

 materials probably came from the remoter crystalline region of 

 Canada. East of Clinton there is a more rapid thinning of the 

 beds, since the "old Appalachian highland that limited the sea in 

 this direction is soon reached. The Pennsylvanian and southern 

 Clinton deposits were laid down on the western shore of the 

 Appalachian highland; their materials were probably gathered 

 from this land mass rather than from the north. 



There is an interval of more than loo miles between the 

 eastern end of tlie New York belt- and the next appearance of 

 the Clinton rocks to the south, which is in central Pennsylvania. 

 It is possible, however, that th.is gap is due to the overlapping 

 of the higher Upper Siluric members which are represented in 

 eastern New York and pass into Pennsylvania in the vicinity of 

 Port Jervis. A comparison of the faunas of the Clinton in New- 

 York and Pennsylvania shows a close relationship that is sug- 

 gestive of stratigraphic continuity, the buried portion comiiij^- 

 to the surface only after it becomes involved in the Appalachian 

 folds. 



MINING METHODS 



From the beginning of active mining along the Clinton belt, 

 attention has naturally been directed to the northern edge or 

 outcrop of the beds as being the most accessible for develop- 



