MI'RPHREE'S VALLEY; ECONOMIC GEOLOGY. 99 



from the solid, heavy bedded, rigid members, whose dip is 

 always found to be remarkably uniforn. 



At other points the dip found was always less than at 

 the edge of the iron ore. It varied from place to place, but 

 was no where to be found less than 10. The average dip is 

 certainly more, but to avoid an over estimate, it was hypo- 

 thetically assumed that the dip of the iron ore is 10 N. W. 

 That would give from the edge of the limestone a descent 

 beneath a horizontal line, of 100 feet in 450 the length of 

 the slant surface. To this must be added the descent of the 

 surface in that distance, 45 feet. Making the whole thick- 

 ness of the deposit IJfd feet. But it is also probable that the 

 limestone at this point, has been pushed up above the ore 

 bed. It has that appearance. If so, the bed is thicker by 

 the amount concealed by the limestone. It is also probable 

 that the top of the slope, from whence the measure was taken, 

 had been denuded, and was not therefore the actual top of 

 the deposit. From all evidence therefore afforded here, it 

 may be safely assumed, that this deposit is 150 feet thick. 



A little to the S. W. of this place, the limestone does not 

 come to the surface, and the out-crop of the iron ore extends 

 much farther down the hill, and therefore shows a much 

 greater thickness of ore ; but how much of this might be due 

 to sliding, could not be determined, and hence DO safe esti- 

 mate could be made here. 



A quarter of a mile to the N. E. and near the middle of 

 the same section (5) a wash has cut through the iron ore 

 deposit. The limestone beneath it is slightly exposed on 

 the S. E. side. This is the extreme N. E. end of the expos- 

 ure of the Cambrian Limestone. The iron ore deposit has 

 been denuded down to the level of the floor of the valley in 

 a N. W. direction. Its out crop along this wash is mainly 

 obscured by silt, and shows but little ore. The edge here is 

 over 200 yards broad, from S. E. to N. W. 



On the face of the hill to the N. E. is shown from 150 to 

 200 feet of the irony clay which mainly constitutes the ore 

 bed. The whole face of the hill is composed of it, but for a 

 considerable distance no iron ore was found in it, and only 



