41 8 STRATIGRAPHICAL GEOLOGY. 



than that of the qiiartzite, though all the rocks may have a westerly clip. 

 The quartzite extends southward along the ridge of Sugar Loaf mountain, 

 and is followed both on the south and west by protogene gneiss. Near 

 the summit of Black mountain, and on its southern slope, is a greenish 

 chloritic and micaceous schist. At an old mill between Black mountain 

 and Sugar Loaf is a conglomerate composed chiefly of quartz, quartzite, 

 and pebbles of a whitish indurated schist. Where the quartzite outcrops 

 in Haverhill, on the road north of Mrs. S. Tenney's, it is associated with 

 hornblende schist, as is also the mica schist on the south side of Black 

 mountain. On both sides of the quartzite in Haverhill we have proto- 

 gene gneiss ; and it suddenly terminates here, unless it forms a transition 

 state into the arenaceous whetstone slate near E. Dean's. 



In Piermont, quartzite is found in the east part of the town ; and in 

 the north part, where it is crossed by the section, we find gneiss ; on the 

 east and on the west, wrinkled mica schist, that carries staurolite, horn- 

 blende and mica schists. Farther south, on Piermont mountain, there 

 is protogene gneiss on both sides of the quartzite ; and there seems to 

 be the same doubling of the strata that we find in Benton. As it extends 

 south and passes into Orford, a short distance east of where the road 

 crosses the town line, south-west of the mountain, the rock is a quartz 

 schist. Near the house of P. C. Savage, in Orford, it is a quartzose mica 

 schist ; and it seems to be the case, nearly everywhere that this band 

 thins out, that it forms a transition state into mica schist. In the north- 

 east corner of Dorchester, between McCutchins pond and the summit of 

 Smart's mountain, a band of quartzite has been traced. Whether it is 

 connected with that to the west of E. Lamprey's we have not been able 

 to determine, though, from the many isolated bands elsewhere, it is not 

 improbable that this may be. The rock on both the east and west sides 

 of the summit of Smart's mountain is a friable, tender gneiss ; and it has 

 the protogene gneiss on the west and the Lake gneiss on the east. The 

 unconformability of this band of friable gneiss with the other gneiss will 

 be shown when we come to speak of the common gneiss. 



The quartzites, quartz schists, and quartz conglomerates of Gilsum, 

 Surry, and Keene are among the most interesting of any we have exam- 

 ined, but they require a much more careful study than we have been able 

 to give them, to understand fully their relations to the other rocks. Then 



