J, D. Dana—Helderbery rocks in the Connecticut Valley. 349 
white portions are feldspathic, as is proved by their fusibility 
before the blowpipe, while the light gray are quartz, and some 
short darker lines are micaceous. ‘Thus this region, like that 
of Berkshire, demonstrates that gneiss and quartzite are rocks 
of the most intimate relations, as intimate as mud and sand 
along seashore flats. Part of the feldspathic layers widen at 
intervals into forms an inch or more thick at the middle; but 
they are generally nearly even. 
4, Hornblende rocks of the purest kind, and of great extent, 
are here so intercalated with quartzite and mica slate, and so 
Helderberg. Hence, in the era of the Lower Devonian, the 
Connecticut Valley, from the latitude of Bernardston northward, 
through to that region, the lithological resemblance suggests 
identity of age, though ngt proving it without a further strati- 
- At Littleton, also, fifty miles south-southeast of Lake 
Memphremagog (S. 24° E.), there is a limestone, half metamor- 
phosed, containing Helderberg corals—one of the important 
discoveries of Prof. Hiteheock, to whom I am indebted for 
guidance over the region. The limestone is associated with 
quartzite and cla slate, and also with a series of chloritic rocks 
Portly feldspathic, including chlorite slate and a kind of proto- 
gine in which a pseudophite-like mineral is disseminated in 
small grains; and it appeared to me that all were conformable. 
* Hunt’s Address, page 12. 
