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Prof. O. P. Hubbard on Erosion in New Hampshire. 165 
the road, for a distance of near half a mile, where it is only one 
foot wide; it may also be traced some way on the eastward side 
of the road. 
In my note-book are memoranda of pot-holes measured here, 
some of which (the last three) have been since in part removed, 
1. 16 inches diameter and 4 feet 
C..,0mnd yA ot 
2, 4A feet 
3. 3hand4ft. “ and10 “ « 
A. Ad feet & 
e008: 83 ty. @ 
5. *3 “ and 12 “ now less than a semicircle. 
ee eee 46 and 8 “ “a semicircle. 
ce ff “ and10 “ “in two curves, as if two 
holes had been worn into one 
No. 1, was filled with peat, and discovered by sounding with 
an iron bar; at a single blow the bar struck on the bottom a flat- 
tened, rounded smooth stone, of about four pounds weight, which 
was the last agent in the excavation of the hole. ‘There is also 
a rocky channel some rods in length, oblique from the northeast, 
which is cut off by the railroad at its lower end; it is twelve feet 
wide and eleven feet deep, and contains near its mouth large 
Tounded granite boulders from one to seven feet diameter. Such 
masses as these, with the great number of similar ones, large and 
cess, some may have escaped from the excavations and were car- 
ried over the south summit (s), or were lodged on its north side. 
levels, while this erosion was in progress. ‘The well” beside 
the road has been lowered three feet on one side, so as to form a 
channel in which the early road was made, while below this level 
it was perfect and eight feet deep. We may suppose, with rea- 
Son, that these wells had been of similar dimensions through a 
long period while the action was’ going on, and that excavation 
below kept pace with the removal of the upper portion. 
Between these two remarkable barriers on the north and south, 
the excavation in granite of this longitudinal valley is more than 
forty feet deep and six hundred feet wide; it has a very uneven 
Surface, with rounded hummocks rising from the bottom, as 
shown on the E. and W. side of the railroad, in a section from eight 
