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diorites, more or less micaceous, passing into coarse feldspathic 

 gneiss, as at Natick, but nothing like quartzite or felsite. 

 There are frequent passages into the exotic series. According 

 to Prof. Hyatt, the character of the drift in the vicinity of 

 Wenham Lake indicates the occurrence there of much stratified 

 rock ; and the area just described is probably continued in that 

 direction. The rocks about Wenham Lake, judging from the 

 specimens in Prof. Hyatt's collection, are much the same 

 as in the Reading series. A finely stratified rock, similar 

 to the principal member of the Reading series, sometimes 

 a diorite and sometimes a gneiss, and occasionally epidotic, 

 composes most of the area in Boxford and Rowley. I have 

 little doubt that this area extends south-westerly with increasing 

 breadth to the Montalban border. The dip and strike are as 

 before, and the indications of a passage into the eruptive diorites 

 very plain. Among the diorites in Newbury, north of the 

 Boston and Maine R.R., there is a considerable amount of 

 stratified rock similar to the last, but including quartzite. 

 Strike, JST.E. ; dip, N.W. It occurs in small patches, which 

 have not been explored sufficiently for their delineation on the 

 map. 



The well-known schist enclosed in the granite on Marble- 

 head Neck undoubtedly belongs to the stratified group. It is a 

 fine-grained rock, often largely quartzoze, and always containing 

 more or less micaceous or hornblendic material, usually in a 

 condition so fine and obscure as to be scarcely recognizable 

 with the naked eye. Large masses of a similar schist occur in 

 the granite at Hospital Point, on the Beverly shore ; and also 

 in the Naugus Head eruptions on the north side of Great 

 Misery ; though in this last case I am not certain that the 

 stratified rocks do not belong to the Naugus Head series. 



In what precedes I have, I think, placed beyond question the 

 proposition that the stratified group and the unstratified diorites 

 are essentially one and the same series ; and yet the strongest 

 evidence remains to be adduced. Irregular fragments and 

 patches of the micaceous quartzites and felsites are of common 



