346 CONGLOMERATE. 



gneiss immediately east. The beds of the conglomerate vary from one to ten feet in 

 thickness those of the gi'een schists never exceed three feet. A system of east and west 

 joints crosses the ledges, cutting the pebbles in two as well as the rock itself; the face of 

 the joints is smooth as may be seen in specimens, a few of which have been obtained. 

 Single pebbles may be divided in the middle by some of these joints. The subject of the 

 elongation of the pebbles and their division is of great importance to our theoretical 

 knowledge, and is therefore fully treated in Part I. 



North of Wallingford bowlders of coarse sandstone are occasionally seen, as in the 

 north part of Rutland, which probably are from the sane layer. Upon the west side of 

 Bald Peak, at Grangerville in Pittsford, there is a very coarse conglomerate associated with 

 quartz rock. The pebbles are often several feet in diameter, and are mostly composed of 

 quartz. 



Although the formation has always been regarded as purely silicious, a large amount of 

 limestone is associated with it; whether as integral constituents or the result of plication 

 is not positively settled, though the probabilities are in favor of the former supposition. 

 In Shaftsbury, west of E. Stone's house in the northeast part of the town, there is con- 

 siderable limestone, and we should not be surprised to learn that it extended to Benning- 

 ton along Furnace Boook. There is an extensive bed of limestone in Mendon, near the 

 quartz rock, whose connections have not been traced out. At Goshen there is a north and 

 south valley in the midst of the quartz rock, in which lime is said to exist : but we have 

 made no search for it. It is not unlikely that a small amount may be found there. At 

 Lake Dunmore there is a considerable width of silicious limestone west of the lake, 

 between two ledges of quartz rock, all dipping east. The quartz rock is semi-vitreous 

 near the lake, thus showing a considerable degree of metamorphosis. The west edge of 

 the quartz rock and the east edge of the great range of crystalline limestone is a mongrel 

 calcareo-silicious rock approaching in character the peculiar mixed rocks of the Red Sand- 

 rock Series. 



It is likely that this band of limestone continues into Bristol, for in the valley of the 

 north branch of New Haven River, passing up to Starksboro, there are ledges of limestone 

 occasionally seen, interstratified with the quartz, nearly as far as Starksboro Village, and 

 there is reason to suppose that it may extend to meet a narrow belt of limestone running 

 south from Hinesburgh. The valley running from Hinesburgh to Bristol east of Hog 

 Back Mountain is apparently formed principally by the softer nature of the rock the 

 limestone situated in it. 



A narrow strip of impure limestone partially separates the quartz rock from the red 

 sandrock in Monkton. The limestone gradually thins out and is finally lost, so that the 

 quartz rock and red sandrock unite with each other ; and probably the line of junction is 

 only a line separating different degrees of metamorphic action upon the same formation. 



Divisional Planes. 



Joints and a structure allied to cleavage are very common in this formation, though our recorded obser- 

 vations are meager. 



Locality. Strike. Dip. Ol&erver. 



Sunderland, N. 25 E., 90, C. H. H. 



Sundcrland, crossing do., E. and W., 74 W., C. H. H. 



