GLACIAL PHENOMENA IN MAINE. 145 
the wind blows due north.” The locality was, 
indeed, especially interesting from several 
points of view. It is one of the few instances 
I have seen in which a dike, being composed 
of a softer paste than the adjoining rock, has 
yielded more readily to the ice-plough, and is 
cut to a lower level, thus forming a broad, flat 
furrow, the upright walls of which are scored 
as deeply as the horizontal surface of the dike. 
Another most important fact is, that the tide 
daily flows across these marks. Evidently, 
then, they have not been made by water, since 
water has no power to erase them, or to ob¬ 
scure them by other lines of the same kind. 
A mile and a half to the south of Bass Harbor 
there is a ledge facing north, on which the 
glacial characters also point to the north. At 
Seal Cove, however, on the southwestern shore, 
the marks have again a north-northwesterly 
direction. South of Seal Cove all the surface 
inequalities are moutonnees , the striae running 
north-northwest. We returned to Trenton 
Bridge by the western shore, having thus 
skirted the whole island. 
Before closing these remarks I wish to 
allude, in passing, to some other facts con- 
