370 B. K. Enter son — " Bernardston Series" of 



The type of the hornblende rock, as seen in the area described 

 above, and in many bands stretching across the country to 

 South Vernon, a type from which there is little variation, is a 

 dark gray to black, fine grained, wholly massive rock, resem- 

 bling so exactly, especially in its jointing, an intrusive diorite, 

 that it was connected with the Mesozoic diabase in the first 

 work of President Hitchcock, and the occurrence of it faulted 

 between mica schist and quartzite at the South Yernon station, 

 was called trap, by so experienced an observer as Professor C. 

 H. Hitchcock in his latest work on the area.* The hornblende 

 is generally arranged in fibrous radiated tufts, just visible with 

 the lens, which aids in giving the rock its great toughness. It 

 is not prone to weathering, and stands up generally in long- 

 ridges, the schists having been considerably lowered on either 

 side of it, but at the railroad cutting in South Yernon, its fis- 

 sures were coated with an abundant deposit of calcite and 

 pyrite. 



Because of its position in the hollows between the horn- 

 blende ridges, the mica-schist, which really occupies much more 

 of the surface than the former, seems, on casual inspection, to 

 be of subordinate extent and importance. 



The thickness of the beds, calculated on the average dip of 

 22° is, quartzite 107 meters, mica schist 113 meters, hornblende 

 rock 158 meters ; which is certainly far too large judging from 

 the long line of outcrops farther northeast, and it is probable 

 that each is partially repeated several times by cross faults. 



I have elsewhere suggested that hornblende bands of this 

 type are generally derived from limestone beds, and in fact the 

 hornblende bands are still locally quite rich in carbonates, as at 

 the locality first described above just east of Fall River, the 

 broad hornblende band contains layers of limestone 20-30 mm 

 thick ; and farther northeast, at a large chestnut tree east of the 

 end of the Purple blind road, there occurs in the same associa- 

 tion a bed nearly a meter thick of impure limestone carrying 

 garnet and pyroxene. 



The development of hornblende at the upper surface of the 

 crinoidal bed has been detailed above, and the large develop- 

 ment of hornblende in the quartzite in South Yernon points in 

 the same direction.. The hornblende derived from calcite has 

 always a very low absorption. 



The feldspathic Quartzite. — Reserving the question of the 

 identity of this rock with the basal conglomerate, I may first 

 call attention to its curious distribution on the map. It occu- 

 pies a broad area along the eastern border of the schist series, 

 dips everywhere away from it to the eastward with apparent 



* Geol. N. H., ii, 438. 



