r54 NEW YORK STATE MUSEUM 



crop© (1022 and 1023) are of a fine gramed, easily rotting, black 

 and white gneiss, wMch is fairly basic and full of coarse, more 

 acid, pegmatitic streaks. It is one of tbe hornblende gneisses 

 which crop up in all situations in the Adirondack^, but rather 

 suggests some of the Grenville gneisses. 



A little beyond, -J- mile east of Horseshoe station, on Mr Low's 

 narrow gage railway, is a rock cut (1024) in a thoroughly 

 gneissoid, granitic rock made up of microperthitic feldspar (some 

 60/^), quartz (25^) and hornblende and magnetite. The rock is 

 medium coarse, tends toward a granitic, rather than a granulitic 

 structure, and, while differing somewhat from the usual run of 

 the granite which is associated with the syenite, is likely refer- 

 able to that. 



On the Xew York Central and Hudson Kiver railroad, J mile 

 south of Horseshoe station, is a rock cut (1025) in a coarse red 

 gneiss, quite similar to the last except for being less gneissoid, 

 so that strictly it is a slightly foliated granite. For a mile north 

 of Horseshoe there are no rock cuts, though there are several 

 deep cuts in the heavy drift there. In these are many boulders 

 of black and white gneiss similar to the rock south of the pond 

 (1022). These boulders often show graphite scales and tend to 

 emphasize the reference of that rock to the Grenville series. 



Southwest from the station, on the narrow gage, a rock cut is 

 met at a distance of J mile. Here is a hornblende gneiss of vary- 

 ing grain, with crushed and drawn-out augen of white feldspar. 

 The track here runs about with the strike (n. 55° e.), and on the 

 north side of the cut is a much more acid, almost granitic gneiss, 

 which is plainly interbanded with the other. Each is quite like 

 the corresponding type of the previous roclvs and indicates that 

 there is here a belt of prevailing acid gneiss, interblended with 

 hornblende gneisses which sometimes approach amphibolites^ 

 neither rock closely resembling any of the syenite phases. The 

 point to be emphasized is that this is a narrow band, hemmed in 

 by the igneous syenites and granites on both sides, and with the 

 syenite also blocking its course to the northeast along the strike, 

 at no great distance. 



