Chester amphibolite. 



80 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



Here the following section is exposed, from below upward, i. e., from west 



to east: 



Section at Roive serpentine quarry. 



Feet. Inch, 



Rowe schist 1. Sericite-schist. 



/ 2. Hornblende-schist 7 



I 3. Talcose schist 1 



I 4. Serpentine, showing structure of 



j amphibolite 450 



I 5. Talcose schist 4(5 



I C. Chloriteschist 7 



Savoy schist 7. Sericite-schist. 



Total thickness, from 1! to inclusive 510 1 



No. 4 is a serpentine altered from amphibolite; 3 and 5 are masses of 

 schistose talc, representing a fiu-ther stage of the alteration. It abounds in 

 dolomite. It has been extensively quarried, but the large buildings erected 

 for working it are abandoned. 



THE BAST rORTAL FAULT. 



The series maintains a width of about 30 rods down to a point 100 

 feet above the Deerfield River, and the continuation of the band can not 

 be found across the river on the south; but it is shifted a mile to the 

 west, to Mount Serpentine, by an important fault running in the bed of 

 the Westfield River at this point. It is thus earned beyond the limit 

 of Franklin County, but as it is still within the Hawley quadrangle 

 its further course is traced to the point where it enters Worthington, in 

 Hampshire County. 



The steep mountain rising west of Rice's tavern, at the east portal 

 of Hoosai' Tunnel, and easily distinguished from the others that surround 

 the valley by its bare precipitous walls, is Mount Serpentine, and is a 

 great mass of the rock Avhich has given it its name. Its north face seems 

 to be the face of the fault here described; its east wall appears to be 

 formed by the peeling off of the vertical schist from the massive serpentine. 



The mountains as seen from the valley are projections of the plateau, 

 notched by the successive brook gorges; and taking the road running up 

 southwest from Rice's tavern, one finds at the first brook-crossing a 

 magnificent bowlder of serpentine, and can climb by this brook to the 

 serpentine overhead. By following the road to the first house, and then 

 going 50 rods west, one comes on the serpentine, after passing a band of 



