C. H. Hitchcock—Labradorite Rocks in New Hampshire. 47 
gee Lake, and also occur in connection with porphyritic gneiss. 
Red Hill in Moultonboro is also composed of a similar syen- 
tension into New Hampshire, in Seabrook, is accompanied 
yY porphyritic gneiss, with crystals of feldspar less conspic- 
uous than usual. 
Rocks in this mountainous district recently brought to light, 
and possibly related to the Norian or Huronian, are the jas- 
ers of Albany and Twin Mountain, and extensive deposits of 
felsite capping Lafayette, Flume, Liberty, Twin, and other 
mountains. Chemical examination may show them to be rela- 
ted to the lime feldspars. They will be analyzed in due 
time. 
me. 
There is an abundance of material afforded by these facts 
for speculating upon the ages of the metamorphic rocks in 
w Hampshire and Massachusetts. One cannot avoid form- 
ing conclusions as fast as new facts present themselves; but 
as I hope to be able to make further investigations in this field, 
it will be best to reserve our inferences for some other occasion, 
_— additional information may afford more satisfactory re- 
sults. 
rock js chrysolite. Mr. Dana has consented to publish his 
results in an article following this. 
Hanover, N. H., Dec. 1, 1871. 
