412 STRATIGRAPHICAL GEOLOGY. 



4. The Coos Quartzites. 



These rocks pass on the one hand into quartz-schists, and on the 

 other into quartz-conglomerates. The chief constituents of the latter 

 are quartz and quartzite pebbles, from those that are very small to those 

 that are a foot or more in their longest diameter. In some places the 

 pebbles are very distinct, while elsewhere it requires weathering to show 

 that the rock is not a common quartzite. Although in a very few places 

 the pebbles are nearly round, there are many localities where they are 

 oblong, and sometimes they appear to be elongated and bent. In the 

 north part of Springfield, Vt., on Rattlesnake hill, there are a few argilla- 

 ceous pebbles, probably derived from the Cambrian slates. 



In this area there are two distinct bands of the Coos quartzites. One 

 is in the immediate valley of the Connecticut ; the other is to the east in 

 Unity, and is an extension southward of the main band that has its origin 

 in Landaff. 



The Western Band. 



The most northern outcrop of the quartz-conglomerate in the section 

 we are describing is on Rattlesnake hill in Springfield, Vt., and here it 

 appears to be an isolated area. It is composed chiefly of flattened quartz 

 pebbles. There are, besides, a few fragments of slate ; and the strata dip 

 east at a high angle. The rock on both sides is calciferous mica schist. 

 South along the Connecticut river the Skitchawaug mountain, extending 

 from the first school-house in Springfield almost to the Cheshire bridge, 

 is also a quartz conglomerate, and the strata have a high easterly dip. 

 At one point it is probably continuous to the second road running par- 

 allel with the Connecticut, as it outcrops immediately east of the road 

 near J. D. Chase's. In some places the rock has the character of an in- 

 durated schist, and the pebbles can scarcely be recognized, but elsewhere 

 they are very distinct. In Charlestown the most northern point where 

 the rock was seen is Rattlesnake hill ; and on top of this hill the pebbles 

 are almost altogether quartz and quartzite. The largest are from four to 

 five inches in diameter ; but descending to the railroad the pebbles dis- 

 appear, and the rock has the character of many of the quartzites. The 

 rock has a high westerly dip. Thus, with rocks opposite, we have a dis- 

 tinct synclinal axis. 



