C. H. Smyth, Jr. — Clinton Iron Ore. 495 



reach the ore they must be so loaded with lime as to be able to 

 take up little, if any, more. At Clinton, wherever the ore has 

 been broken in any way, this abundance of lime in the waters 

 is shown by a deposit of calcite, tilling cracks and cavities. 



This idea of replacement of organic forms before they were 

 incorporated into the rocks, or, at least, before the mass of 

 which they form part was buried under any considerable 

 amount of sediment, raises the question, ' Was not the oolitic 

 ore originally calcareous, the spherules being altered in the 

 same way, before consolidation?' While there is nothing to 

 absolutely disprove such a supposition, and further study may 

 lead to its acceptance, it seems, on the whole, rather improb- 

 able. In the tirst place, the conditions seem to have been 

 more favorable for the formation of an iron, than of a lime 

 oolite, and so there is good reason for accepting the simpler 

 and more direct explanation. As before stated, the absence of 

 any traces of calcite in the spherules precludes the idea. 

 Further, the analogy of the Cuba ore suggests direct deposi- 

 tion. In the truly oolitic ores seen by the writer there is a 

 marked absence of fossils, while the non- oolitic types are full 

 of traces of life. This indicates some decided difference in 

 the conditions under which they were deposited. The simplest 

 explanation seems to be, that while the non-oolitic ores formed 

 along shore lines subject to wave and current action by means 

 of which the organic remains were concentrated and brought 

 within the influence of the ferruginous waters, the oolitic ores 

 were deposited in partially or wholly enclosed basins, in which 

 the water was too strongly charged with mineral matter to sup- 

 port much life. As both varieties would often be forming 

 simultaneously quite cl<3se together, it is not strange that they 

 show a tendency to grade into each other. The oolitic ores, 

 then, were precipitated as such in shallow basins, while the 

 non-oolitic varieties are a substitution product, but this substi- 

 tution of iron for lime took place while the organic fragments 

 were being rolled about in the shoal waters, or after they were 

 loosely aggregated in a mass somewhat resembling the coquina 

 of the Florida coast. 



These suggestions as to the origin of the Clinton ore, of 

 course, apply only where it is associated with shore deposits. 

 But even with such conditions, it is highly improbable that the 

 explanation will suffice for every case. On the contrary, it 

 seems certain that, with a large amount of ferruginous material 

 brought into sediments forming along several hundred miles 

 of coast, iron deposits would be accumulated by various proces- 

 ses. Probably some beds of Clinton ore were formed by 

 replacement, as ordinarily understood ; others by original depo- 

 sition as outlined above ; and still others by a combination of 



