LOWER SILURIAN. 



213 



the folded-up slate, that is, lying either in an anticlinal or a synclinal. 

 In other parts of the range, facts prove that the Taconic slates lie in a 

 synclinal, the limestone passing underneath them. Fig. 395 B repre- 

 sents this condition in Mt. Eolus in Dorset, Vt. (Vermont Geol. Rep.), 

 3,148 feet in height; and Mt. Equinox and Spruce Peak are similar. 

 Fig. 395 C, from Emmons, represents the same in Graylock, 3,505 feet 



Fig. 395 B. 



Fig. 395 C. 



Mt. Eolus, Dorset. Graylock. 



high, and it answers also for Mt. Washington, in southwestern Mas- 

 sachusetts, whose highest peak (Mt. Everett) is 2,634 feet high. Fig. 

 395 E exhibits alternations of limestone, quartzyte, and gneiss, on the 

 east side of a small valley, four miles east of Great Barrington,.Mass. ; 

 and 395 D, the same on the west side of the same valley ; and ap- 



Fig. 395 D. 



Fig. 395 E. 



West side of Konkaput Valley 



East side of Konkaput Valley. 



parently they are portions of a low anticlinal which spanned the 

 valley. The above sections are sufficient to illustrate the upturned 

 condition of the beds. 



2. The Crystalline Condition of the Beds The limestones were 



once common fossiliferous limestones, as fossils in some localities 

 prove ; and the other rocks were sand-beds and mud-beds, partly fos- 

 siliferous. All are now crystalline ; the limestones having been con- 

 verted into white and clouded marbles, the quartzose sand-beds into 

 quartzytes, and other sedimentary strata into clay slate (partly good 

 roofing slate), hydromica schist, mica schist, chlorite schist, and gneiss 

 and other rocks. The crystallization increases, though very grad- 

 ually, from north to south, and from west to east, along the range. 



3. Extensive Fractures and Faults. — Fractures and faults are 

 ma*ny ; but one fault had great extent. Fig. 395 F (from Logan) 



