503 
[Crosby. 
189*.] 
This is most obvious at the western extremity (Pl.X V), where 
the melaphyr and the sedimentary strata curve around the granite 
and dip away from it on both sides. Southward from this point, 
between Beal Street and Beal’s Cove, the structure is mono- 
clinal, and the ledges afford a nearly continuous section across 
the entire conglomerate series and a considerable thickness of the 
overlying slate, the latter undoubtedly marking the position of a 
synclinal axis ; but the south side of the syncline is probably cut 
off by the boundary fault, for we seem to pass abruptly from 
the slate to the granite. 
In the vicinity of Hockley Lane (PI. XIV), a transverse fault 
appears to separate this normal succession of the strata from an 
inverted succession which extends thence eastward to Main 
Street or beyond. The melaphyr is now on the south side, over- 
lying the conglomerate ; and these stratified rocks, although oc- 
cupying a synclinal position between the granite on the north ancl 
south, are, we must suppose, bounded on both sides by important 
dislocations and terminated on the east by the great fault along 
the east side of Hingham Harbor. 
Northwest from the western extremity of the granite axis, a 
very steep, narrow, and broken monocline separates the granite 
from the great trough holding the main body of slate (Pis. 
XV, XVI). This faulted monocline is marked by a secondhand 
of melaphyr, which broadens toward the northeast, forming the 
large quadrangular area of this rock east of Huit’s Cove (PI. XVI) . 
This is the largest exposure of melaphyr in Hingham ; and, although 
it appears to be bounded on all sides by downthrow faults, the 
quaquaversal dips of the bordering strata show that, in a lesser 
degree, it is essentially similar in its structural relations to the 
granitic area. On the west side, the upper bed of conglomerate 
and the slate are seen to dip away from the melaphyr. On the 
north, the downthrow of the sedimentary rocks is sufficient to 
conceal the conglomerate, and the slate lies with conformable 
strike against the melaphyr. On the south, the narrow mono- 
cline separating this body of melaphyr from the granite broadens 
somewhat, until it reaches the fault at the northwest end of 
Squirrel Hill, where it changes, perhaps abruptly, to a broad, 
shallow syncline of melaphyr and conglomerate on the south, 
separated by a strike fault from a gentle, southerly monocline of 
conglomerate and sandstone on the north. These features profit 
