Field Relations and Description of the Formations. 201 
resulted simply from metamorphic action. Most of the schists are 
still further complicated by the presence of secondary quartz, 
calcite and epidote. The physical character of the rocks has 
also been greatly altered by folding, faulting and the production 
of schistosity. The original grains of quartz and feldspar have 
been crushed and drawn out into augen or even well nigh ob¬ 
literated by the long continued and powerful pressure. All por¬ 
tions of the island have suffered metamorphic action, but there 
is some diversity in the amount and degree of the alteration. 
The slates and schists on the east side of Conanicut are least 
altered; there is a decided increase in the complexity of the 
metamorphism toward the west, though there is no uniformity 
in this progressive change. There are limited areas on the east 
side which exhibit as extreme cases of folding, crushing or of 
superinduced schistosity as any area on the west shore, but the 
former areas are less extensive and less abundant. 
FIELD RELATIONS AND DESCRIPTION OF THE FORMATIONS. 
The oldest rock on the island is the compact, flinty slate al¬ 
ready mentioned. It is homogeneous in structure, dark green 
in color and very much jointed. It shows few traces of cleav¬ 
age and schistose structure; it is unfossiliferous. The green 
color is not normal but is due to the secondary development of 
chlorite and epidote. The slate is unconformable both with the 
schists and the granite. Its strike is N. E. ; its dip averages 
about 45° to the S. W. The strike carries the slate directly 
into the granitic mass to the south of it, the contact between 
the two being very clearly displayed in the southern part of 
the island. The actual contact between the slate and the 
schists has not been observed, but the transition from the soft 
sericite schists to the slate is very abrupt, taking place within 
the space of two or three rods. There is no agreement in dip 
or strike between the two formations; unconformity certainly 
exists between the two. This unconformable relationship should 
be enough to refute the common belief among geologists, who 
have investigated this area, that the slate is merely the schist 
metamorphosed by the eruption of the granite through it. 
/ 
