331 



tain, we find a beautiful mica-slate which cleaves into large 

 tables, and is generally destitute of limestone. The dip of this 

 is 40 degrees E., and it extends one and one third miles. Then, 

 just below the top of East Mountain, upon the west side, there 

 is about fifty feet thickness of hornblende slate, of which the dip 

 is 28 degrees E. Passing into the valley of the Deerfield River, 

 gneiss is found, becoming gradually nearly horizontal. Between 

 this rock and the hornblende slate above, it is hard to draw the 

 line. Most of the gneiss has hornblendic layers interstratified 

 with it sparingly ; but at the top of the gneiss the hornblende 

 predominates ; the rock being in some places nothing but a heavy, 

 unctuous, shining mass of hornblende crystals. West of Shel- 

 burne Falls the gneiss begins to dip to the west. The extent of 

 the gneiss is four and one third miles, mostly in a deep valley. 



At East Charlemont the hornblende slate is found above the 

 gneiss, corresponding in character and thickness to the same 

 rock in Shelburne. Then follows the beautiful mica-slate, spar- 

 ingly interstratified with limestone, and lastly the calcareomica- 

 slate, corresponding to the rock at the east end of the section. 

 Here, at the end of the section in Charlemont centre, the strata 

 are perpendiculai-, running north and south, and stand side by 

 side with talcose slate. 



The Deerfield River makes a bend just above Shelburne Falls, 

 so that the section crosses the river twice, and continues for two 

 or tliree miles further in the valley. Had a section been meas- 

 ured across the river at Shelburne Falls village at right angles 

 to the stream, it would have exhibited a mountain, west of the 

 river, possessing all the characters of East Mountain in a reverse 

 order. Thus we find an anticlinal axis, with the same strata upon 

 the opposite sides of the ridge at their proper distances. The 

 inference is that the strata were once continuous, and that the 

 material has been denuded. A measurement upon the protracted 

 section gives 3,350 feet, or three fifths of a mile, as the height 

 above the present level of the former strata. This is taken from 

 the lowest level upon the section. As we go east or west from 

 this central point, the surface rises ; consequently the thickness 

 of the denuded sti'ata constantly diminishes in these directions. 

 The denuded surface is eleven miles wide. 



From the bend in Deerfield River above Shelburne Falls the 



