GEOLOGY OF THE CONNECTICUT VALLEY DISTRICT. 43 1 



chapter. The licklcrbcrg area contains an unusual amount of this rock, 

 and it seems proper to refer the c^rcater part of it to the same horizon 

 witli the hornblende bands of Slielburne r\'i]ls, Mass., l^rattleboro', and 

 the long belt from Marlboro' to Reading, Vt., Westmoreland, Plainfield, 

 Hanover, Orford, Canaan, etc., N. H. Often the rock is properly a horn- 

 blendic gneiss, and for that reason has not been distinguished from tlie 

 gneiss adjoining. In New Hampshire it seems to encircle areas of the 

 Bethlehem group. This suggests whether we ought not to incorporate 

 with these protogenic rocks other gneisses similarly enclosed, but devoid 

 of talc or chlorite. Objection has very properly been niade to separating 

 formations by means of mineral characters ; but we have now the means 

 of uniting common and talcose gneisses in this Bethlehem series, which 

 may be characterized mineralogically by the presence of the talc in a 

 portion of the group. The classification is based upon stratigraphy, not 

 lithology exclusively. We may be able to say that the gneiss of Shel- 

 burne Falls, the range between Marlboro' and Ilartland, Vt., as well as 

 the small Bratlleboro' area, should all be ranked as part of the Bethlehem 

 series, and hence probably corresponding with the Laurentian in age. 



The hornblende rocks occur on both sides of the Hinsdale area. On 

 the west we have an excellent outcrop opposite the mouth of 15road brook, 

 dipping 50" east. It is about two hundred and fifty feet thick, of a glossy 

 black color, often containing epidotic nodules (Nos. 47, 48, of the cata- 

 logue). On the north edge of the gneiss we find it at H. Streeter's (Nos. 

 50, 52), and above the Thomas saw-mill (No. 47). On tlie eastern border 

 it appears east of S. E. Butler's (No. 51), at Davenport's island, and fifty 

 rods cast of F. Doolittle's (No. 46). These arc all in Ilin.sdale. After 

 crossing into Vernon I have noticed the same material, outside of the 

 gneiss, near the Whithed cemetery. 



After reaching the line between Vernon and Northfield, an abundance 

 of hornblende rock, with a fine-grained gneiss, makes its appearance, 

 both of which seem to belong to a formation above the Vernon or Beth- 

 lehem gneiss, as just described. Both occur abundantly farther south. 

 On the town line the dips are all easterly, hence indicating inversions. 

 The details will be described presently (Fig. 70). On a line diverging from 

 this section, at the crossing of the state line by a road from Lily pond 

 south-easterly, and thence following the track as far as the rocks extend. 



