GLACIAL DRIFT. 197 
ogy of Massachusetts, and in his text-book. He says of it,—“ From top 
to bottom it has been scarified on its northern and western sides. On 
its lower parts, especially on the south-west side, the striae run about N. 
W. and S. E., by the magnetic needle, as they do in the country around 
the mountain; but, when we approach its top, the course changes to N. 
10° W. and S. 10° E. Other strize are seen here on steeper slopes, both 
northern and southern, than I have found elsewhere.” 
The observations given in the table were mostly taken in 1871. It 
would appear that the common direction in the vicinity of Monadnock 
is about S. 12° E., the towns north showing a few degrees additional of 
easting, while the mountain itself, from the lake to the south-west corner 
of Jaffrey, about eight miles, exhibits, on its north-west flank and southern 
edge, the south-east course. After looking over the whole area, one sees 
that the ice coming from the north and west of north struck the moun- 
tain and clung to it closely, so much so as to run much more easterly on 
the south edge than elsewhere. Over the region to the south-east all 
trace of this easting is lost, the striz in Jaffrey running S. 11° E., much 
like those of Troy and Marlborough. I have not explored the east side 
of the mountain; it is mostly covered by trees. Hence it is impossible 
to decide upon the value of Mr. Wheelock’s theory, from present explora- 
tions. I understand his view to be, that Monadnock was an island in a 
sea full of icebergs, which struck equally strong upon both the north-west 
and south-east sides. There is certainly a dearth of striated ledges upon 
the south-east side, while even the earth has been largely removed from 
the north-west flank, so mighty has been the planishment of the rock. 
The striz on the south-east side should all point south-westerly, if the 
summit were an island scarified on both sides by icebergs. Mr. Whee- 
lock’s paper is a very valuable one; and that part which relates to strize 
is herewith reproduced. 
Strie on Mt. Monadnock.* Waving, in the last three years, spent many days in 
studying the striz upon Mt. Monadnock, the writer is unwilling that the results of his 
observations should be lost for want of record, especially as they seem to have an im- 
portant bearing upon unsettled questions of surface geology. This mountain is pecul- 
iarly favorable to such study. Its long spurs radiating from a central elevation, though 
* American Naturalist, vol, vii, 1873. 
VOL. 111. 26 
