]26 ANNALS NEW YORK ACADEMY OF SCIENCES 



The advocates of this theory are numorons. Tn order to set forth the 

 arguments given in favor of this theory, ihe wi'itei- ((iiotes from several 

 of its leading advocates. 



Quoting E. C. Eckel (37, pp. 32-33) : 



'•The priiicipjil faets supporting,' the theory of sediiiuMitary origin may he 

 hrietiv .suiuinarized as f()lh)ws: ■* 



"1. In mining fi-om slojics runniu!; down on tht> dip of tlic on> hcd. when 

 •once the limit of surface weathering is i)ass(Hl — and this may l)e at any point 

 from 1 to 100 feet heh)w tlie outcrop — no further important change in tlie ore 

 is found with increasing depth ; thougli a nuuil)er of mine worlcings are now 

 close to 2,000 feet from the outcrop. 



"2. A numher of horings in Alabama have struck the ore at i)oints from one- 

 half to one mile back from the outcrop, and at dei)ths of 400 to SOO feet below 

 the surface. The ore encountered in tliese borings was hard ore of the usual 

 qualit.v, and not merel.v a 'ferruginous limestone." Several borings in New 

 York have struck Clinton ore at distances of from 10 to 1." miles back from 

 the outcrop. These borings showed good ore at de])ths of 0(>4 to S)!)') feet below 

 the surface. 



"3. The physical character of the oolitic ore cainiot readily be explained on 

 any replacement theory, while the formation at the present day of original 

 oolitic materials is a matter of common knowledge. 



"4. The occurrence of fragments of the ore in overlying beds of limestone 

 in the Clinton formation as described by Smyth, points to the fact that the 

 ore had l)een formed prior to the deposition of tliis limestone. 



"5. If the replacement theory were accepted, one would expect that the ore 

 beds would show a greater vertical range; that is, tliat they would at places 

 occur in rocks of other than Clinton age. Throughout their entire extent, the 

 Clinton beds are closely associated with Silurian and Devonian liniestont>s and 

 shales, some of which offer excellent receptacles for the replacement dei)i)sits, 

 but the characteristic i"ed ores are coutined to tlie Clinton itself." 



The author goes on to say that primary replacements did not exist to 

 any great extent, but, although no definite proof has been found, it is 

 probable that some secondary replacement has since taken ])lace. Leach- 

 ing, of course, is noted. Eckel has done a very considerable amount of 

 work on these ores while engagcil in the ecoiiomic woi'k of the U. S. 

 Geological Survey, and, although his principal investigations wci'c upon 

 the deposits of the southern states, lie included a wide extent of Clinton 

 deposits in liis special study, and his views must be recognized as founded 

 upon accurate information and a bioad knowledge of the literature 

 available. 



According to Professor C H. Smyth, .Ir. (317), the replacemenr 

 theory for the origin of the Clinton ore was not substantiated by the 

 facts in the field. The calcareous rocks would certainly have caused the 

 iron to be precipitated while it was passing through them, yet the ore is 



