98 
eastern shore, the continuation of the boundary fault on the 
Nantasket side. The downthrow is, of course, to the north, 
and evidently greatest toward the eastern shore; for north of 
this fault, on the western shore, we again find the granite and 
basal conglomerate. The granite rises somewhat: abruptly to a 
height of from twenty to thirty feet on the west end of the hill, 
and is immediately overlain by the conglomerate, matching Gran- 
ite Point on the Nantasket side. The hill is precipitous at this 
end on both the north and south sides, being bounded by fault- 
scarps ; and these natural sections show that the granite is cut 
off in its eastward extension beneath the conglomerate by a 
north-south fault having an easterly throw of perhaps 10 or 20 
feet (Fig. 12). This fault appears to end in the east-west 
faults, and accounts for the form of the conglomerate outcrop, as 
shown on the map. The basal conglomerate on this hill is 
similar to that south of the boundary fault, except that the 
pebbles include a large proportion of compact forms of mela- 
phyr, and the red jasper is more conspicuous. The dip is S. E. 
5 10% equivalent to a thickness of thirty or forty feet. 
W. E, 
Granite. Conglomerate. Melaphyr. 
Fic. 12.— AN BAST-WEST SECTION ACROSS ROCKY 
NECK, NORTH OF THE BOUNDARY FAULT. 
SCALE, I INCH = 400 FEET. 
The conglomerate is certainly separated from the melaphyr 
on the southeast by a fault, which is probably an extension of 
the southwest- northeast fault in the granite, already referred to, 
but with the throw reversed (Fig. 12). This melaphyr is the 
compaet, green and purplish, jaspery variety—the first melaphyr 
— which normally overlies the basal conglomerate; and it is 
