1864.1 471 [Lesley. 



made to our hand. The fact, that it occurred just under, in, or near a 

 great ore deposit, must be regarded as an accident, until we have 

 found enough more lignite deposits connected with ore beds to make 

 some organic or original connection between them supposable. And 

 even then, it must be remembered, that the search is wholly confined 

 to the ore-deposit localities, which of itself would throw doubt upon 

 their connection, even if we had a sufficient number of instances. 



I will now give as clear a description as I can of the ore banks of 

 Mont Alto, so as to show, if possible, the actual relationship of the 

 lignite to the ore ; granting, in advance, that the description will 

 leave much to be desired. 



The brown-hematite ore-deposits of Mont Alto follow the outcrop 

 edges of the slates and sandy limestones which form the southeastern 

 edge of the Valley, as shown in section. Fig. 1, Plate VIII. The 

 ore is in fact nothing but the residue of these beds after decompo- 

 sition and dissolution, the honeycombed and altered edges of the 

 Silurian slates and sand-limes themselves, after their lime has been 

 washed out of them, and their carbonated and sulphuretted iron has 

 been hydrated and peroxidized. The muddy slates formed the pre- 

 sent deposits of small ore with white and red clay. The sandy lime- 

 stones formed the present harder, silicious, rock-ore belts. The 

 geologist can procure, in the banks, specimens of every stage of this 

 interesting process, from the perfect limestones which refused to dis- 

 integrate, and the iron-lime-sandstone with the disintegration and re- 

 crystallization begun, to the perfect ball and pot ore of radiated, 

 acicular, crystallized brown-hematite. The great variety in the com- 

 position of the original rocks has been the cause of a great diversity 

 in the ores taken from the different openings. But two principal 

 distinctions may be particularly noticed ; viz., that the ores which have 

 resulted from the decomposition of the slates are more disposed to 

 the redsTiort side, whereas the ores which have resulted from the 

 decomposition of the limestones are more or less coldshort; probably 

 because of the sand in the limestone; it is, in fact, called by the New 

 York geologists the Calciferous Sandrock. The slates, on the con- 

 trary, are apt to hold a small percentage of sulphur ; or perhaps we 

 should say, are less likely to permit the abundant drainage needful 

 for carrying off the sulphur in the form of a salt. Sometimes in the 

 same deposit there is a mixture of the two varieties, producing a 

 neutral ore. But it is not often that such large exposures of both 

 varieties occur in the same neighborhood, as is the case here. 



Taking into view all that we know of these deposits along the 



