Geology and Mineralogy. 317 
pposed by 
, be Professor Hitch- 
cock to be eruptive, may be for the most part, if in all 
not in all cases, 
8. 
The chief facts of interest in the valley region is the occur- 
rence at three places of limestone containing Lower Helderberg 
fossils—corals, crinoids, or brachiopods, associated with various 
metamorphic rocks. These places are in Littleton and North Lis- 
The section given on page 
326 of the Littleton rocks represents a synclinal of slate (the 
f the “ Lis- 
i yman, Li 
bon, and Helderberg groups. On pages 329 and 331, this con- 
formability is again exhibited in sections, and also on plate xi. 
Hitchcock, however, calls the Lisbon and Lyman groups 
uronian, a conclusion that is not suggested by the above-men- 
on 
ley. The rocks of the west side in this part are, going southward, 
a light-colored well characterized granite (“Conway Granite”), 
