50 NEW YORK STATE MUSEUM 



who have worked in the southern fields where the occurrence of rich 

 ores at the surface is at times succeeded by lean, limey ores in depth. 



The evidence in support of both views has been traversed very 

 thoroughly by C H. Smyth jr, in a paper^ which represents as well 

 the results of long experience and close study of the Clinton ores 

 both in the northern and southern districts. There can be no doubt 

 after an impartial perusal of Professor Smyth's paper that the 

 theory of sedimentary origin is fully substantiated for most of the 

 occurrences. For the ores under present consideration this is the 

 only explanation at all compatible with the conditions. 



The stratigraphic features presented by the New York section 

 of the Clinton do not lend themselves to the conception of vertical 

 circulations of ground water such as would be required to dissolve 

 and carry iron from the overlying strata. The ore beds everywhere 

 lie nearly horizontal ; their dip is universally toward the south at 

 an angle no greater probably in many places than that given by 

 the contour of the original sea bottom on which they were deposited. 

 At no time in their subsequent history have they been steeply in- 

 clined. Moreover, they are overlain by thick shales not readily 

 permeable to water. Underground flowage must necessarily be 

 limited and be dependent for the most part on the cropping out of 

 the more porous strata like the limestone and sandstone layers. 

 Thus, it is directed rather along the bedding planes than across them. 

 Below the ore there is also more or less shale intervening before the 

 top of the sandstone and conglomerate basement is reached. 



The existence of limestone above the ore beds has been remarked 

 by Professor Smyth in the paper already quoted. In Cayuga and 

 Wayne counties the fossil hematite is covered directly by limestone 

 and there are one or more layers at varying horizons in the shale. 

 The main ore bed in this part is generally split into two portions by a 

 thin seam of limestone. No noticeable replacement has taken place 

 in the overlying limestones, though this would be the first to be 

 affected by descending iron-bearing solutions. The limestones are 

 fine grained and compact and, where protected by shale, they show 

 little effect of leaching in the mass or of solution along the joint 

 planes. 



The ore beds are separated by sharp division planes above 

 and below, with no intervening zone of gradation from ore to 

 rock. This feature is well illustrated in the process of open-cut 



iZeits, fill- prak. C.eol. Aug. I894. Sec also paper in Am. Jour. Sci. 1892. 143:487. 



