THE CONWAY SCHISTS. 185 



Across Franklin County the rock is a rust\-, contorted, dark-gra>' mica- 

 schist, with few g'arnets, rarely or never spangled with l)iotite, much twisted 

 and full of quartz veins, and abounding in black graphitic and biotitic 

 limestone beds, often very impure. The ledges present, as a whole, a most 

 uniu\'itingly ragged and dark, rusty appearance. The rock is folded into 

 a series of closely appressed folds in the liroad area over which it extends, 

 and it is not possible to unravel them and lay them down separately upon 

 the map. ^ 



SUBORDINATE BEDS IN THE CONWAY SCHIST. 

 THE GNEISS BEDS. 



There are in several places in the dark schists light-colored beds of 

 a fine-grained gneiss or feldspathic quartzite. The transition from the one 

 rock to the other is very sharp, and in the strong folding the rocks have 

 undergone the gneissoid beds are found in attitudes relative to the schists 

 which suggest an intitisive origin of the former. The small plienocrysts 

 of feldspar often show twin striation and quite regular outline, and the 

 latter is true of the quartz and the red-brown mica. The groundmass is so 

 fine as to give the whole the aspect of a trachyte, but with a strong lens it 

 is seen to be sandy rather than felsitic, and in thin section it is seen to be a 

 finely granular clastic mass, nearly all of small and rounded quartz grains, 

 with much clayey dust, and clear traces of the enlargement of quartz grains 

 and the later growth of the small feldspars and mica scales 



The most marked bed crosses the road a few rods west of the house of 

 R A. Gates in northwest Leyden. It is 13 rods wide, runs a long way 

 north and south with the strike, is generally regularly intercalated in the 

 inclosing schists, but in places irregularly thrust into them, and is accom- 

 panied by small parallel beds, a foot or less in width, which seem like oft- 

 shoots of the main bed. 



It also occurs in Whately, just west of the village, and near the houses 

 of G. Cowan (where the bed is 12 feet wide) and Mrs. ]\I. Taylor, and in 

 Chesterfield opposite the schoolhouse on the Clark road. 



There wei'e apparently sudden transitions from the coaly clays to a 

 fine calcareous sand, which have allowed the development of the small por- 

 phyritic lime feldspars and only a very small quantity of dark mica. 



