112 WHITE : OATLAND COT^IPLEX OF IGNEOUS ROCKS. 
The basic and acid rocks probably have therefore a circum- 
ferential junction, though the main junction has not apparently 
been yet exposed. It is also clear that the basic rock was intruded 
prior to the more acid rock, though how long an interval elapsed 
between the intrusions remains to be determined. 
Just south of the small fault in the granitite is a very narrow 
(about 2 ins.) and almost vertical dyke of greenish quartz associ- 
ated with pads of a soft green, fibrous, asbestos-like mineral 
(actinolite ?) which closely resembles the "fibrous tourmaline" 
(Memoir), which occurs in similar veins in the Dhoon granite in 
the N.E. of the island. This quartz dyke appears in the quarry 
apparently striking to the X.E., and in a low crag of the basic 
rock cropping out in the adjoining field in this direction the vein 
was again found visible traversing both the diabase and the veins 
of granitite, and associated with the same fibrous mineral. 
The granitite at the southern end of the quarry is very soft,, 
decomposed and stained. 
A rock which closely resembles a certain facies in the Oatland 
complex is visible about two miles to the N.X.E., near Ballabunt,. 
and it is noteworthy that rocks with similar affinities occur as- 
bosses in St. IVIichael's Island, and Langness, also in dykes running 
N.E. and S.W. along the coast to the east of Oatland. 
AGE OF THE INTRUSION. 
Unlike the Foxdale granite, and still more unlike the Dhoon 
granite, the rock at Oatland shows practically no sign of shear 
movement, and may be ascribed to a somewhat later date. This 
is confirmed by the effect the igneous mass has had in altering, 
the dip of the cleavage in its vicinity. 
But even the most basic modification at Oatland gives no evi- 
dence of the presence of either the monosilicate or bisilicate of 
magnesium, and, in the Avriter's knowledge, it resembles all the 
undoubtedly pre-Carboniferous intrusions of the island in this 
respect, but for the same reason is likewise in strong contrast to 
the olivine-bearing extrusions and intrusions of Carboniferous 
or Tertiary age. This would stiU leave the age of the intrusion 
of the granitite an open question as evidence seems to point to 
the lapse of a considerable interval between the intrusion of the 
more basic and more acid types in the complex. 
