1S73.] * [Lesley. 



Such is the most general statement of the geology. I reserve details 

 of geological structure for the close of this note : merely alluding here 

 to the fact that any one possessing the key to the geology can perceive a 

 perfect regularity in the apparent confusion of the deposits. 



II. The quantity of ore in this helt depends on three considerations, 

 all of them variable : 



First : On the original charge of iron in the slate and calc-sand strata. 



Second : On the dip of these strata as they descend from the side of 

 the mountain. 



Third : On the depth beneath water-level to which the mouldering 

 decomposition of the strata and the peroxidation, concentration and 

 crystalization of the iron has extended. 



First. It is not to be expected that the slate formation as a whole was 

 equally charged with iron everywhere. Consequently at some points 

 along this belt (of 20 miles) a greater quantity of ore is to be expected, 

 and a deficiency of ore in the intervals. It is probable however that 

 workable quantities will be found on almost, if not on quite, every mile 

 of the belt. In five or six parts of the belt ore exists in millions of tons. 

 At no one point have scientific mining operations revealed more than a 

 small portion of the actual length, breadth and depth of the ore. At 

 some places the intervals between two large mines are evidently occupied 

 by ore to the same extent as at the mines actually opened. It is safe, for 

 instance, to consider the whole interval between the Old Bank and the 

 Strickler Bank as a continuous deposit of ore. 



Second. A steep dip narrows the outcrop of ore ; a gentle dip broadens 

 it. At the new pits opposite Boiling Springs the dip is about 6°, almost 

 that of the surfaces ; consequently, pits sunk anywhere on the gentle 

 foot-slope of the mountain over a space 1000 to 1500 feet wide and from 

 half a mile to a mile long, strike ore within five or ten feet of the surface 

 ("sometimes at the surface) and go down through it to an unknown depth, 

 at least 25 feet. 



Third. This dip, whether steep or gentle, carries the ore down north- 

 ward under the Calciferous Sandstone in which the Yellow Breeches 

 Creek has cut its course. How far the ores can be followed down, north- 

 ward, under the bed of the creek toward the interior of the Great Valley, 

 and whether or not shafts of 500 to 1000 feet sunk on the north bank of 

 Yellow Breeches Creek would strike the slate formation in a decomposed 

 condition, that is, in the form of clays holding iron ores, no one can tell 

 until trial be made ; but there is every reason to believe that the ore 

 mined at the surface, at the foot of the mountain, forms in quantity but 

 a small portion of the whole production of ore to be got hereafter under 

 the valley of the creek. 



From these considerations, I judge that the quantity of ore attainable 

 by proper mining operations has no easily assignable limit, and may 

 furnish supplies for centuries. 



The present survey was expressly limited to the iron ores on the line of 



