84 NEW YORK STATE MUSEUM 



glacial erosion. The ice apparently has performed most of its work 

 in removing whatever weathered and disintegrated material may 

 have accumulated on the surface in the long interval between its 

 advent and the exposure of the granite to atmospheric agencies. 

 Since the Glacial period the rock has hardly been affected by 

 weathering; fresh unstained samples may be secured from the 

 natural ledges. Over much of the area the hill slopes have been 

 denuded of their former soil and drift covering, as the result of 

 recent forest fires exposing the surface to rapid erosion, so that the 

 granite nearly everywhere is well exposed. 



On the western boundary the granite is in direct contact with 

 the great syenite intrusion of the Diana-Pitcairn area that has been 

 mapped and described by C. H. Smyth, jr. The contact where 

 crossed by the railroad lies just west of milestone 56. The syenite 

 here has a very basic composition, containing much magnetite and 

 dark silicates, with a coarse texture. It is much like gabbro in 

 9,ppearance. The contact of the two intrusives is not clean-cut, 

 sharply dividing one from the other, but over a considerable dis- 

 tance both granite and syenite occur in alternating sekms and patches 

 or as interlaced bands. In the hasty examination of this mixed 

 zone nothing definite could be learned as to the time relations of 

 the two intrusions. The granite, however, is in general the most 

 massive. The stretch from contact to about milestone 57 on the 

 western border consists of gneissoid granite with a marked parallel- 

 ism in the arrangement of the light and dark minerals and rather 

 finely granular texture. The ledges between milestones 57 and 60 

 reveal the granite in thoroughly massive or indistinctly gneissoid 

 condition and rather coarse in grain. The color is red, pink or 

 sometimes mottled by the appearance of white feldspar in addition 

 to the colored variety. One phase seen near milestone 59 shows 

 porphyritic red feldspar in white groundmass of feldspar and 

 quartz, specked with black hornblende crystals. At Jayville, a 

 former iron-mining locality, situated near the middle of the area, 

 there appears a considerable body of black hornblende gneiss which 

 seems to have been caught up by the granite on its way to the 

 surface and is possibly a part of the older Grenville series. It is 

 in this gneiss that the magnetite bodies are found. The next ledge 

 beyond Jayville consists of the normal red granite which continues 

 to milestone 61 where a white granular gneiss with rusty streaks 

 outcrops for a short distance. These are the only large inclusions 



