9 
(Nantasket), the concluding pages, especially, relating to the 
glacial and more recent phenomena and the non-lithified de- 
posits of the distriet, will apply to the northern or beach area as 
well. Hence the scope of the paper really embraces the entire 
area of Hull, or Nantasket in the broad, original application of 
the name.! The mouth of Weir River, or Weir River Bay, 
forms, in the topographie sense, the natural western boundary of 
the Nantasket area; yet, geologically, it is impossible to exclude 
the promontory of Rocky Neck, in Hingham. This rocky head- 
land is lithologically and. structurally identical with the district 
ast of Weir River Day, while it is completely separated from 
the other and dissimilar sedimentary areas of Hingham by the 
ledges of granite on the south and southwest and the drumlins 
of Planter’s Hill and World's End on the west and northwest. 
The natural boundary line between the geologic areas of Nantas- 
ket and northern Hingham appears, therefore, to be, not Weir 
River Bay but the eastern shore of Hingham Harbor. The 
southern boundary or limit of Nantasket is clearly marked by 
the continuous depression formed by Straits Pond, Lyford's 
Liking and Weir River Day, which is continued, as a narrow 
strip Qf marsh, south of Rocky Neck to the bay which sharply 
indents the eastern shore of Hingham Harbor. This topographic 
trough defines with approximate accuracy the present border of 
the Boston Basin, separating the sedimentary and volcanic rocks 
from the somewhat more elevated granitic area on the south, 
Although the line of depression just traced is a natural and 
important geologic boundary, it has appeared best to give this 
paper greater breadth and completeness by including in its scope 
not only the sedimentary and volcanic rocks of Nantasket, and 
the granite floor upon which they rest, but also a sufficient 
breadth of the granitic border of the basin to make apparent 
the marked contrast in geologic structure on opposite sides of 
= 
'The outer islands of Doston Harbor (the Brewsters, Calf Id., Green Id., etc.) belong 
to the town of Hull. But the geology of these formed the subject of a previous paper 
(Proc. В. S. N. IL, XXIII., 450-457); and will be more fully described in a later paper 
of this series. 
