Postelsia 310 
a more shaly habit is seen in its structure and a 
rougher, more forbidding aspect is presented in 
its appearance. 
As the westernmost surfaces are reached on 
the islands off the entrance of the bay, a shaly 
habit is dominant in the rock of this formation; 
huge dikes break through the shales and crum- 
ple, twist and wrinkle them into many shapes 
(Plate XXX).. The even, monotonous strike and 
dip are destroyed and a contorted slate is devel- 
oped which curls and winds around the huge 
dikes in many quaint formsand curves. These 
rock masses may be followed by boat from one 
rock island to another and along the precipitous 
shore from the entrance of the bay to the dock 
where rocks were first seen on our arrival at port. 
The culmination of this contortion is seen on 
some small islands along the west side of the 
entrance to Port Renfrew harbor (Plate XXXII. 
fig. 1.) Aninteresting intermingling of contorted 
slates and intruding dikes is soon found. On 
this west side of the bay the slates disappear, 
giving place to another and overlying formation. 
West of Port Renfrew bay, not only dikes but 
