340 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



dark-greeii, epidotic quartz veins. Between this and the Monson gneiss to 

 the east the lower coarse mica-schist crops out. In tliin section the feld- 

 spars are largely tri clinic, and the constituents are larger and clearer than 

 elsewhere in the series, but much crushed. The epidotes are especially 

 large and well crystallized. Titanite, which is not wanting in the other 

 sections, is especially abundant here. An analysis of this rock is given on 

 page 336. 



The band is covered by heavy sands across Slmtesbiu-y, but reappears 

 at "Mount Boreas," above Pratts Corner, and a mile east of the pond a mile 

 south of South Leverett. The Avestern half of the hill is made up of the 

 whetstone-schist, so crushed that dip and strike can be determined with 

 difficulty, and the eastern slope by an equally crushed quartzose amphibolite, 

 while below, by the stream, is a tonalite which is somewhat gneissoid, and 

 is doubtless the continuation of the ornate rock mentioned above, though 

 from the greater amount and the colorlessness of the quartz and feldspar it 

 has not its attractive appearance. This rock continues across Pelham in a 

 narrow band resting in the foothills against the older gneiss and sepai-ated 

 by a broad area of sands from the feldspathic mica-schist of the center of 

 Amherst. It is a highly hornblendic granitoid gneiss, much intersected by 

 epidotic quartz veins and often very chloritic. 



The large mass of leek-green honistone known locally as Shav's flint,^ 

 from the tradition that it was used for flints during Shav's rebellion, was 

 found on Amethyst Brook, in Pelham, just where this band crosses it. It 

 was a bowlder, and its origin was unknown. Some years ago I found 

 the same material in place where the band of hornblende -gneiss (altered 

 tonalite) crosses the south line of Pelham. It forms beds in the latter 

 sometimes as much as 20 feet thick, and at times crosses the bedding. It 

 is a cryptocrystalline quartz, colored green by chlorite derived from the 

 decomposing hornblende of the granite, passing from green to flesh color 

 and weathering white and grading into ordinarj^ gneiss, and it is a result 

 of the thorough crushing and silicification to which the rock has been sub- 

 jected. The veins colored by epidote are not essentially different from 

 these, though they do not reach such large dimensions, and where the 

 fissure is not entirely filled they show beautiful plane, polished surfaces of 



' For the history of the rock, which has been called plasma, prase, and green hornstoue, see 

 under "Quartz," in A mineialogical lexicon: Bull. U. S. Geol. Survey No. 126, 1895, p. 135. 



