GEOLOGY OF THE MERRIMACK DISTRICT. 50/ 



the state that are its equivalents. The northern area, that in Grantham 

 which forms the elevation known as Giles pinnacle, may be three hundred 

 and fifty yards in length, and is probably five hundred feet in width. As 

 the outcrop is surrounded by drift, this limit may be far too small, and 

 the drift also prevents our knowing what rock the quartz penetrates. The 

 nearest rocks, however, are common gneiss. The rock is not often a pure 

 white quartz, but is generally of a dull yellow or of a reddish color. In 

 many places it contains cavities that are lined with quartz crystals, and 

 it frequently encloses decomposed feldspar. Sometimes there is a ten- 

 dency in the rock to a banded structure, though this is not common. 



The outcrops of the quartz in Grantham are not so prominent as those 

 of Grafton. Here the quartz has been worn away nearly to the level of 

 the other rocks, and everywhere that we have seen the quartz it rises 

 above the rock it penetrates in proportion to its width. The character of 

 the rock is very much like that of Grafton. It outcrops on the road that 

 runs south-east from the Methodist church, and at D. S. Hastings's where 

 it forms quite a hill, and on both sides of it we have gneiss. It can be 

 seen west of N. Shaw's, and southward it crosses the road at the forks 

 near W. G. Winter's, and below, at R. Winter's, there is a prominent ledge. 



In Croydon, north-west of East Village, near W. R. Bartlett's, we find 

 the quartz penetrating the protogene gneiss, and it contains iron ore both 

 limonite and hematite. The masses are sometimes four or five inches in 

 diameter. The quartz is several rods in width, and from the principal 

 area it sends off veins into the surrounding gneiss. 



The next outcrop southward that we have examined is on Quimby hill 

 in Unity. In width it is much more extensive than the rock in Gran- 

 tham. It is more compact, and has fewer cavities. There is also another 

 outcrop on the hill directly south of Quimby hill. The drift conceals all 

 the rocks except the quartz, but as there is a protogene gneiss east, it is 

 more than probable that the quartz penetrates it here as in Grantham. 

 We also find quartz at the south end of Perry mountain, and some of it is 

 very white. It is here very near a band of quartzite. This quartz is 

 probably the source of the very white quartz boulders scattered through 

 Langdon. 



In the south-west part of Surry there is quite an extensive area of 

 quartz, and at Mine ledge it attains a greater width than anywhere else 



