yO NEW YORK STATE MUSEUM 



There is certainly a great fault between the limestone and the 

 eastern edge of the ore, since north along the railway the limestone 

 gives way to greatly brecciated gneisses. Farther north again 

 gabbro appears, but in irregular exposures mingled with horn- 

 blendic gneisses and quite difficult to understand. The ore itself, 

 however, outcrops as a marked band or bed in green syenitic 

 gneisses, and runs to the north for nearly a mile, with occasional 

 pits. The Cheever at the southern end is, however, the chief one. 

 These workings, now being revived after years of idleness, dip 

 down steeply, at 50 or 6o°, then flatten at somewhat over 200 feet 

 vertically from the surface and run westward until cut off by a 

 fault. Their relations are shown on the accompanying section 

 [fig. 5] reproduced and reduced from the bulletin of the New 

 York State Museum 14, page 346. The only point of revision 

 lies in the fact that our recent fuller knowledge of the basic syenite 

 gneisses, makes the occurrence of unbroken gabbro on the east 

 doubtful. Field observations the past summer led to the con- 



Fig. 5 Cross-section of the Cheever mine 



elusion that much of the black hornblendic gneiss, formerly taken 

 for gabbro, is basic syenite gneiss, but massive gabbro does occur 

 mingled with it. The ore is a band in the syenitic gneiss, here 

 quite quartzose, and about 150 feet from the undoubted Grenville. 

 Below the ore 50 feet of similar gneiss appears before the basic 

 rocks take its place. As the ore bed is followed north the dip 

 appears to flatten and in an old working about half a mile from 

 the Cheever slopes, the strike is north and south and the dip 20 w. 

 The same wall rocks, however, appear. 



Another outcrop of ore appears along the present highway a 

 quarter of a mile north of the old Cheever engine house. It strikes 

 northeast and dips southeast. It has limestone not over 15 feet 

 above it and while thus apparently stratigraphically higher or 

 nearer the limestone than the position of the western end of the 

 Cheever, if we consider it the same bed, it suggests a synclinal 

 basin for the ore, with a pitch of the fold to the south. There can 

 be no doubt that a north and south fault on the west beneath a 

 meadow cuts off both the ore and the Grenville series in this 

 direction. 



