GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 433 



and hence that the whole series of rocks was presumably of the same 

 general age. Professor Dana has called specific attention to the differ- 

 ence in lithological aspect between the two slates, and is well satisfied 

 that the clay slate of West mountain is an earlier unconformable forma- 

 tion.* This is undoubtedly the correct view. 



Commencing at the north end of this field of description, I will enu- 

 merate the position of the slates along sectional lines. First, in Brattle- 

 boro' and Chesterfield. In the west part of Brattleboro' village, the 

 Calciferous mica schist underlies the slates, both dipping 50° E. Farther 

 east the dip 60° W. has been observ^ed. At the depot the dip averages 

 66° south of east. At this locality I noted some interesting irregularities, 

 represented in Fig. 6S. The slates indicate an anticlinal dip, those at the 

 south end of the cliff being inclined at a less angle than the others, which 

 are vertical. Each side exhibits a band of quartz, sometimes bent and nod- 

 ular, but indicating an identity to the enclosing slates. Between them is 

 an older hard rock, separated distinctly by faults from the slates upon both 

 sides, showing most decidedly upon the south, both by divergence in dip 

 and a distinct fissure. This harder rock may not belong to an older for- 

 mation, but the layers certainly underlie the clay slates. On following the 

 ledge around to the village, it is seen to be much crushed and bent out of 

 place. I think many other ledges of slate would display similar irregulari- 

 ties if carefully studied. At the east end of the bridge over the Connect- 

 icut in Chesterfield the slates dip 80° N. 80° W. To the east of this the, 

 slates dip easterly, thus forming an anticlinal support to underlie the Coos 

 schist of Wantastiquit mountain. The synclinal is observable both north 

 and south of the Brattleboro' ridge. To the north are interesting bands 

 of quartzite, apparently elevated from beneath like the hard rock at the 

 depot just mentioned. 



South of the Windham county agricultural park in Brattleboro' the 

 slates are minutely twisted, with the general dip of S. 70° E. The line 

 between them and the Calciferous group is crooked. At East Guilford 

 the Calciferous dips 55° E., followed immediately by the slates having 

 the same position. The roofing-slate band lies just to the east of the 

 village, and is supposed to stand at a higher pitch. Near the mouth of 



* Avier. your. Set., iii, vol. vi, p. 343. 

 VOL. II. 55 



