268 B. K. Emerson — " Bernardston Series " of 



Section of the Williams' Farm Rocks. 



1. Garnetiferous mica schist 22*5 ra. 



2. Micaceous quartzite and conglomerate 135* " 



3. Magnetite, maximum. 1* " 



4. Limestone 6* " 



Fault 



1. Mica schist 35- " 



2. Quartzite and conglomerate if conformable with the 



mica schist 200 - " 



The beds below the fault are a repetition of those above. 



a. The Argillite (fig. 3, A, west end). — Beginning nearly a 

 mile northwest of the Williams house, and just north of the 

 point where the road over West Mountain bends sharply west, a 

 long ridge of the typical elaborately contorted argillite extends 

 northerly. Going east a drumlin conceals its contact with the 

 newer rock, and I have represented beneath the till a comfor- 

 mable contact of the argillite and the quartzite as I have found 

 it everywhere in the region. (See fig. 2.) 



b. The western outcroj) of the mica schist. — Where the series 

 outcrops for the first time after crossing the drumlin, a small 

 area of the mica schist of this series has recently come to my 

 notice. It is a garnetiferous mica schist, like the more eastern 

 outcrops, and it lies plainly in a small synclinal of the quartzite. 

 It lies ten rods south of the western of a row of great chestnuts 

 which crown the hill. 



c. The western exposures of the qxiartzite. — The discovery of 

 the schist just described makes plain the structure of these 

 quartzite outcrops with their western dip. As they lie in a 

 small synclinal the quartzite makes a corresponding anticlinal 

 before reaching the outcrop of the mica schist. The rock is 

 dark gray quartzite, at times conglomeratic, weathering very 

 rough, with strike and dip very irregular and uncertain, with 

 many slight slips and crushings, indeed, often completely 

 brecciated and recemented with limpid quartz. Locally it 

 passes into a black siliceous slate by the microscopical develop- 

 ment of biotite and the accumulations of coaly matter. A few 

 scales of the former mineral can be seen with the lens. Going 

 up the hillside from the limestone along the line of dip, two 

 small ledges of the rock appear, as may be seen from the 

 section, widely separated from each other, and from the rocks 

 above and below. 



It is not difficult to find, among the less crushed portions of 

 each ledge, pieces which agree exactly with the quartzite above 

 the limestone, especially that which outcrops a few meters 

 above the latter, and its peculiar appearance is largely due to 

 crushing and infiltration of quartz. The same result is reached 



