The Schists. 
211 
cite, this change, as the structure of the rock indicates, having 
been accomplished by dynamic metamorphism. 
It is the presence of this mineral that gives rise to the sil¬ 
very lustre of these schists. Clastic grains of quartz are found 
in small quantities, but the feldspar altered and unaltered 
makes up the main part of the rock. In all portions of the 
schist rutile is very abundant. It occurs in fine needles and 
in the well known genal twin form. At times this mineral is 
so abundant that it resembles masses of felt. The inclusions of 
iron oxide and siderite are surrounded by broad zones of 
light yellow color arising from the oxidation and hydration of 
the original mineral. The schists in the immediate neighborhood 
of the granite are nearly vertical, but reach a gentler dip to¬ 
ward the head of Mackerel Cove, the dip is E. or slightly N. of 
E., frequently the rocks are overturned and dip west, but this 
is a local phenomenon. The strike is north and south nearly, 
bearing slightly northeast and southwest. Schistosity is so 
well developed that it obliterates the bedding and renders accu¬ 
rate observations impossible. Double schistosity is of frequent 
occurrence, one set of planes dipping N. W. the other north¬ 
east, the latter being better developed. North of Mackerel 
Cove to Round Swamp the dip of the rocks continues to be east 
and that of the schistosity mainly W. N. W. 
These schists are quite uniformly graphitic but do not differ 
essentially from the light schist in any other respect. The same 
structure and the same features are present in both. The tran - 
sition from white to dark and vice versa is usually an abrupt 
one, it is rare to find gradual transitions. So abrupt is the 
change and so frequent are the alternations of black and white 
that sometimes the schists have a banded appearance. This band¬ 
ing is uniform for long distances, in one case it can be traced 
from Freebody’s Hill diagonally across the island to Lion’s Head, 
a distance of four miles. This banding, which is due to alternations 
of sedimentation in the original rock, is of great service in de¬ 
termining the strike of the rocks, bedding planes are usually 
obliterated and their position difficult to determine, the banded 
schists are a means of determining the attitude and trend of 
the rocks where otherwise it is well nigh impossible to do so. 
