THE GNEISS AT SHELBURNE. 39 



outcrop. Here it is not to be disting-uished from the Becket or Monsou 

 gneiss. Under the microscope it is so fresh that tlie quartz and feldspar 

 are scarcely visible without polarizer. Below the falls the gneiss is greatly- 

 dislocated, and many varieties alternate in much confusion. A white l)io- 

 tite-granitoid gneiss is followed conformably by a similar but thin-bedded 

 rock. These are faulted against a greenish gneiss containing many inter- 

 mixed fragments of schist, and against this rests the contorted hornblende- 

 gneiss which furnished the beautiful bowlder now adorning the vestibule 

 of the geological museum at Amherst, which was iigured by President 

 Hitchcock.' The rock is made up of thin bands of a very hornblendic 

 gneiss, alternating with equally thin bands of a white gneiss, and the whole 

 folded with a remarkable complexity. On the south side of the stream the 

 black hornblende rock rests upon the biotite-gneiss exactly as it does on the 

 top of Bald Mountain (now called Massaemet), and it is not impossible that 

 the deep basin has been formed by a sinking of its bottom about 1,200 feet. 

 Bald Mountain is the eastern border of the basin. 



Toward the southwest of the area the rock is a thin-bedded biotite- 

 hornblende-gneiss with few garnets and with pyrite. 



At the contact under the bridge on the road to Charlemont the rock is 

 a rather fine-grained, thin-fissile biotite-gneiss, with few red garnets and 

 some thick, compact quartzose beds. Above this is a very cortorted horn- 

 blende-gneiss. On the road south from Shelburne Falls along the east side 

 of the river, and near the south border of the gneiss, the latter wraps around 

 a great mass of hornblende-schist, as if it were a granite rather than a gneiss. 



It is with some reserve that I identify this gneiss with the Becket and 

 Monson gneisses. The gray gneiss can not be distinguished from the upper 

 portion of the Monson gneiss, except that it is not "stretched." The thin- 

 bedded hornblendic gneiss in many ways suggests the idea that it is devel- 

 oped from the hornblende-schists which surround and once capped the 

 gneiss, and it is unlike the hornblendic layers in the Monson gneiss. I have 

 been brought to weigh these matters with care because of a more serious 

 difficulty. At the Goshen anticline, next south, the calciferous mica-schists 

 are broken through, and we have the normal section in descending order: 



1. Corrugated schists = Conway schist. ) ^ , .„ . , . , 

 „ „, ° , , . } Calciferous mica-schist. 



2. Flags = Goshen schist. \ 



3. Chloritic and hornblende-schists=Hawley schist. 



'E. Hitchcock, Elementary Geology, 1860, p. 26. 



