lO NEW YORK STATE MUSEUM 



The whole rock shows decided evidence of severe dynamic meta- 

 morphism, the feldspars especially being crushed and granulated. 

 Such rock is common on the mountain side one and one-half miles 

 south of Batchellerville. 



5 A light gray, medium-grained, rather massive looking gneiss 

 (occurring in abundance one and one-half miles southeast of Fox 

 Hill and consisting of 30 per cent orthoclase ; 15 per cent plagio- 

 clase-oligoclase to andesine ; 40 per cent quartz ; 10 per cent garnet ; 

 5 per cent biotite ; and a little zircon. Other gneisses similar to this 

 but very fine grained and lacking garnet are prominent at the base 

 of Bald Bluff and also two miles west of Cranberry Creek. 



6 Light gray leaf gneiss. This rock is medium to coarse grained, 

 highly granulated, and contains 25 per cent orthoclase ; 20 per cent 

 microcline ; 5 per cent microperthite ; 10 per cent oligoclase ; 35 

 per cent quartz ; 4 per cent biotite ; and traces of magnetite, garnet, 

 zoisite, and zircon. It is a fine example of leaf gneiss, the quartz 

 crystals being drawn out into long flat forms. Good outcrops occur 

 two miles south of Batchellerville and similar rocks, but containing 

 some garnet, occur well up the face of Bald Bluff and along the 

 road one-half mile northwest of Northville. 



7 A distinctly straight and thin banded, dark, hornblendic gneiss 

 in large exposures three miles northeast of Northville. It contains 

 18 per cent microperthite ; 15 per cent orthoclase ; 10 per cent micro- 

 cline; 5 per cent plagioclase (mostly oligoclase) ; 20 per cent horn- 

 blende in fine green pleochroic crystals; 18 per cent quartz; 5 per 

 cent biotite; 5 per cent garnet; 2 per cent magnetite; i per cent 

 zoisite; and small amounts of zircon, pyrite, and apatite. A rock 

 similar to this but not clearly banded and richer in plagioclase feld- 

 spar is abundant along the northern border of the Grenville area 

 southwest of Sacandaga Park. 



8 A highly schistose rock showing thin, white and dark gray 

 bands and containing 15 per cent orthoclase; 8 per cent plagioclase 

 (oligoclase to andesine) ; 50 per cent quartz; 10 per cent garnet; 

 15 per cent biotite; and 2 per cent epidote and zircon in fine crys- 

 tals. The garnet and biotite are present in tiny specks and flakes 

 respectively. This is a fine illustration of a highly granulated and 

 dynamically metamorphosed, banded sedimentary rock. Large 

 exposures occur two miles west-southwest of Cranberry Creek and 

 one mile east of Fox Hill. 



9 White feldspar, quartz gneiss from large outcrops toward the 

 top of Bald Bluff. It is characterized by the total absence of dark 

 colored minerals and consists of 34 per cent orthoclase ; 20 per cent 



