67 
north-south line, the axis of the syncline dipping east 10° or 
more; which prevents the melaphyr from reappearing on the 
заве side of the hill. 
Conglomerate. 
Melaphyr. 
Fic. 7.—-SECTION ACROSS THE FAULT ON THE WEST SIDE OF CRESCENT 
HILL. SCALE, I INCH = 50 FEET. 
Crescent Hill is, in fact, divided by a series of east-west 
faults. Commencing on the north, the first fault is 65 feet from 
the northwest corner of Crescent Hill and exactly opposite the 
northern end of Great Hill. It downthrows to the north about 
eight feet, jogging the contact of the conglomerate and lower 
melaphyr ; and, since it does not now cut the upper melaphyr, 
the effect is to increase the apparent thickness of the conglom- 
erate. The second fault is thirty feet farther south. It hades 
S. 25° and downthrows in the same direction about eight feet, 
being compensating with reference to the first fault. Twenty- 
five feet farther south is a small dike (43) and the only one 
observed on the hill. Accompanying the dike, but not coin- 
ciding in plane with it, is the third fault, which hades and 
downthrows to the south, the throw being about eight feet, and 
the beds sloping steeply from the fault on the north. The next 
or fourth fault, seventy feet farther south, is that already re- 
ferred to, on the west side of the hill. This is one of the 
plainest and most instructive faults in the Nantasket district. 
neral: view of the fault as seen from 
`: 
Figure 7 represents a ge 
the railroad, taking in the whole height of the hill. The 
fracture is still a well-marked and somewhat open fissure ; and 
the jogging of the contact of the conglomerate and upper mela- 
phyr shows that the downthrow is to the south and about 
