12 
east beneath a bed of melaphyr. The conglomerate of Round 
Hill is connected with that of the plateau by essentially contin- 
uous outerops along the eastern border of the marsh, and must 
be regarded as a part of the same bed. It is of medium texture 
above, passing in the lower part of the hill into fine conglom- 
erate and a considerable thickness (10 to 20 feet) of reddish sand- 
stone ; while in the ledges rising from the marsh on the southwest 
we have a coarse and irregular conglomerate with layers of 
sandstone, which show that in these outlying ledges as well 
as in the hill the dip is mainly to the east or east-southeast and 
very gentle —5° to 10°, but rarely exceeding 5°. The exposed 
thickness of the conglomerate, including the outlying ledges, is 
probably between 75 and 100 feet. The low ledge of melaphyr 
protruding from the marsh on the north side of the hill is prob- 
ably a part of the bed underlying the marsh ; and the fault sep- 
arating this melaphyr from the conglomerate is thus given a 
general east-west course. Since both this fault and that bound- 
ing the marsh on the east cut across the strike of the conglom- 
erate, the breadth of the outerop of that rock, as the map shows, 
has been greatly diminished at this southeast angle of the marsh 
where the fault-lines meet. According to the view here pre- 
sented, the melaphyr forming the floor of the marsh belongs to 
the same bed as that overlying the conglomerate, and hence the 
conglomerate must also underlie the marsh, but at a greater 
depth than the melaphyr. More probably, however, as the iso- 
lated ledge of conglomerate in the channel east of Marsh Island 
suggests, the entire section of Marsh Island and Crescent Hill is 
represented beneath the marsh, the latter being bounded by faults 
on all sides and separated from Round Hill by a slip of at least 
150 feet. 
South of the hill, on the bank of the river ( Lyford's Liking), 
the granite is well exposed, with conglomerate and sandstone 
resting against and upon it. The sandstone is really a fine, red- 
dish and intensely hard quartzite ; and both it and the conglom- 
erate appear to fill fissures and depressions in the surface of the 
granite, in the same manner as the basal conglomerate of the 
