no NEW YORK STATE MUSEUM 



becomes a large ore body. This can best be followed up by itself. 

 In No. 17 the limbs have parted again, so far as yet indicated 

 and the horse of rock has widened. The upper left-hand bulge 

 has drawn in a little more. In Xo. 16 there is a bulge in the 

 western limb, low down, but no very marked change in the other 

 parts. In Xo. 18 we first .encounter the property line and as 

 developments have not been extensively made on the east side 

 the data are not yet available. It is not an unreasonable expecta- 

 tion that the bulge in the lower right-hand limb of the earlier 

 sections should manifest itself in depth to some extent in the as 

 yet undeveloped portions to the north. 



In X^'o. 15 there is little change, but additional data as gained in 

 the future will be of great interest. Between 15 and 14, a very 

 remarkable change takes place. Apparently by a pinch and thrust 

 from southeast to northwest a great bulge or wrinkle was rolled up 

 on top of the anticline hitherto described, and just above its horse 

 or core of rock. The old anticline soon pinches out but the new 

 wrinkle bulges into a great second shoulder or roll, higher up than 

 the one which we have hitherto followed. The latter gradually 

 diminishes and in the end practically disappears between X"os. 12 

 and II. ^Meantime the increasing bulge of the new wrinkle makes 

 the noble ore body which was opened up originally in the Tefft 

 shaft and in the great open cut of the "' 21 *' pit. The central horse 

 of rock itself turns up to the vertical and, in the No. 13, even rolls 

 over beyond it. All these features appear in sections 14 through 11. 

 The upward trend or pitch of the axis of the fold now asserts itself 

 strongl}-, and in X^'os. 10 and 9 we see it almost reach the surface. 

 Between 9 and 8 it emerges and thereafter the ore is in two separate 

 limbs which run through X'o. 6. Beyond this point they have not 

 been much mined in recent years, but, leaving faults out of consid- 

 eration, we should expect the ore to be terminated only by the 

 upward rise of the original outer or eastern edge of the great sheet 

 of magnetite. This edge has been nowhere reached as yet in the 

 deeper mining of the southern sections. It constitutes one of the 

 interesting questions for the future to develop. As to the course 

 of the western limb, when prolonged beyond the workings as yet 

 opened up, it is probably faulted upward in the Old Bed- Welch ore 

 bodies. That is, it probably flattens, encounters the fault shown 

 in sections 13 and 14, is thrown upward and constitutes the Old 

 Bed- Welch ore body with all the convolutions of the latter. If we 

 turn to section 10 in which Old Bed was followed up to the fault 

 line, at about the level of 940 feet, we can see that in order to allow 



