J. D. Dana on Glacier movements along valleys. 241 
ing surface in which there are a few large groovings would 
move, the mass following the general surface, and the portions 
in the grooves nearly or quite the course of the grooves. The 
thickness of the ice that followed the course of the valley was at 
least 2000 feet; for the southerly scratches occur not only on 
the summits of Mt. Tom and Mt. Holyoke, but also on the top 
of Mt. Pocomptuck in Heath, 15 miles west of the Connecticut, 
the low country to the 
place. As Dr. Packard observes, such facts show that icebergs 
were not the transporting agents. 
It is, however, possible that each of these three valleys ar 
. 
and this subsidence 
having been at least 
