C. H. Eitchcock— Helderberg Rocks in New Hampshire. 569 
& 
7) 
Zz 
sandstone with whitish cemen 
arry to €mith’s Brook, 
.—Section from Bronson's Lime 
; 4, Auriferous Con- 
Swift Water series; 
fmith’s Brook; 2, Lisbon group; 8, 8, Lyman grou 
icular quartz ; 9, Lisbon group ; 10, Lisbon village ; th 
nd hornblende; 16, Limestone. 
t 
1 
gneiss a 
Lyman. 
; 8, Len 
Clay slate ; 
Staurolite 
u 
Quartz veins; 6 attends ere % 
; 18, Coos schists ; ond; 15, 
omorete ; 5, 
, Coos slates 
Fig. 10 
14, Mink 
omerate; 4, Slate; 
3 10, Micaceous 
ist ; 
Micaceous bongl 
Mica schist; 9, Hornblende sc 
’ 
, 2, Lisbon group; 38. 
Starch mill 
lage, chloritic ; 
i 
ee 
ter vi 
gh Swift Water village 
ca schist; 7, Swift Wa 
Gneiss. 
6, Mi 
quartzites; 11, 
—Section throu 
5, Gneissic ; 
Fig, 11. 
thickness of this gneissic group 
is 2,500 feet. It is not clear to 
which of the gneissic divisions 
it belongs, though allied to the 
hite Mountain series in some 
respects. 
Crossing Mink Pond is a gray, 
iable mica schist holding in 
The average dip being 56°, the 
thickness must be 3,300 feet. 
mmonoo 
suc (fig. 9). Staurolite is less 
abundant in this than in the 
previous band, and it is almost 
wanting in the western portion. 
With an average dip of 58°, this 
slate must be over 3,000 feet in 
thickness. 
The Swift Water series fol- 
M 
tion for gold at the eastern bor- 
der shows slaty layers, quite 
siliceous, with sandstones, con- 
siderably vitrified. Next is a 
t. Then there are in order acti- 
nolite schist, hornblende schist, white mica schist, and sand- 
