200 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



lamination is marked by alternations in color, in bands 1 to 6 inches 

 thick, exactly as described above. A dike of tourmaline-granite coincides 

 in position with this structure ; strike N., dip 70°-80° E. 



The cleavage is indicated by a bedding which comes out by weather- 

 ing, and along which alone the rock splits easily, and membranes of mica 

 are developed. This strikes N. 40° E. and dips 25°-30 W. There is in 

 this last structure a cleavage changing into a foliation. 



In general cleavage is subordinate in these schists, and usually where 

 it occurs the strike of the primary and secondary structures very nearly 

 coincide. 



FOSSILS (?) OF THE CONWAY SCHISTS. 



In many places cavities coated with rust are found in the quartzose and 

 slightly calciferous beds in the schists, which I have no doubt represent 

 fossils, but which, in every case that has come to my knowledge, are so 

 poorly preserved that it is possible to explain them as due to the removal 

 by solution of some mineral, possibly calcite. The mode of occurrence 

 suggests, however, that a large number of small, flat bivalve shells, 5-25°"° 

 long, were deposited, all lying flatwise and about equidistant in the sands 

 which have now become the whetstone-schists. In a bowlder found on 

 the railroad in Worthiugton these cavities were flattened, nearly round, 

 5-7"™ long. 



West of E. B. Drake's, in the northwest ])art of Chesterfeld, the ca\aties 

 are about 15-25™" long, flattened oval, and in many cases two such impres- 

 sions lie side by side joined by a straight line, strongly suggesting the opened 

 valves of a leperditia like L. haltica. They are flat, rust-covered cavities, 

 and in one fresher part of the rock are represented by darker spots, all 

 arranged parallel to the bedding plane of the rock, and having the same 

 shape as the cavities. These dark-gray spots seem to be only spots in the 

 sandstone. They effervesce much more abundantly than the rest of the 

 rock, and seem to be flattened concretionary patches of a calcite darkened 

 by carbon. 



At the Clarke tourmaline ledge an exactly similar occurrence is found, 

 only the cavities are a little larger. 



At B. Shaw's whetstone quan-y, in Cummiugton, is a bed of the whet- 

 stone about 15"°°' thick, full of closely approximated tubular cavities 2-3°™ 



