characteristic topographic features of the district, although the 
partial submergence of the valleys and the general plateau form 
of the hills causes the elevations to appear incommensurate with 
the otherwise rugged character of the topography. North of 
Atlantic Hill we descend into the great central valley of the Bos- 
ton Basin, now occupied by Boston Harbor; and the pene- 
plain is lost. This is an area of much softer, sedimentary 
rocks, which was deeply and broadly eroded, when the region 
was more elevated, by the united Charles and Neponset Rivers 
and their affluents. 
The lower portions, especially, of the old peneplain, in Cos 
hasset, are to a considerable extent emphasized by level 
expanses of modified drift. The principal sand plain, through 
which project both the drumlins and the higher ledges, ranges 
from 40 to 60 feet in height and extends interruptedly over a 
large part of the town, mantling but not greatly masking the 
contours of the underlying rocks. Although distinctly recog- 
nizable at many points, it has its finest development in and 
about Cohasset Village, between Little Harbor and the railroad, 
rising very abruptly 45 feet from the level marshes of Little 
Harbor to the kettle-dimpled plain on which the village stands. 
North of Strait's Pond and Weir River Day, in Nantasket and 
northern Hull, the modified drift is very scantily developed and 
of no topographic importance. But in the terraces or elevated 
shore-lines traceable at corresponding heights on some of the 
drumlins in Hull and also in Cohasset and Scituate, and aecu- 
rately marking the varying levels of the sea at the time when 
the sand plains were formed, we have a related feature of con- 
siderable interest which will, in its proper sequence, be described 
in detail. 
While the modified drift is, at the best, only a minor factor 
in the topography of this district, the unmodified drift or till, on 
the other hand, occurring almost wholly in the form of drum- 
lins, adds greatly to the topographic relief and diversity. The 
drumlins constitute, virtually, the only elevations in Hull 
north of Atlantic Hill; in fact it is doubtful if this part of the 
peninsula would have any existence as dry land if it were not 
