WHITE : OATLAND COMPLEX OF IGNEOUS ROCKS. Ill 
Man, and though the dip and strike of the bedding are extremely 
complicated, that of the main cleavage is fairly persistent and 
uniform over wide areas. The general dip of the cleavage in the 
" slates " is towards the S.E. on the eastern side of the structural 
axis of the island. For some considerable distance along the 
coast -line east of Oatland the cleavage dip is 60°, and at places 
about midway between Oatland and Foxdale on the W. it has 
the same direction and amount. At Oatland, however, the dip 
is only 30° to the S.E. on the eastern side of the intrusion, while 
on the western side the direction of the dip is reversed. 
The actual junction of the igneous rock and the slates is no- 
where visible at present (1909). 
The intrusive rock itself is exposed in a quarry for road- 
metal in the centre of the mass, and in very low crags of small 
area on all sides. The boss is probably of nearly an oval shape 
where it reaches the surface, the outcrop showing a length of 
nearly 900 yards from N.E. to S.W., and a breadth of nearly 300 
yards from S.E. to N.W. The longer axis is therefore parallel to 
the structural axis of the island. 
Near the centre of the boss a small fault runs in nearly a N.W.- 
S.E. direction, but this was the only sign noticed of any mechani- 
cal disturbance of this character. 
At the centre the rock appears to be a pale, mottled greenish- 
grey, close-textured " granitite," showing chlorite, felspar and 
quartz, and an occasional speck or two of pyrites. 
But on the outskirts of the boss, in the low crags, the rock 
is dark-green, with large crystals of augite or hornblende. 
Pyrites occurs more frequently. The rock resembles many 
others in the island, and may provisionally be termed a diabase. 
In the deepest and most central part of the granitite, opened 
out recently, were found a few rounded knobs of the diabase as 
xenoliths, and, near the margin of the quarry, especially on the 
north-eastern side, were many sub-angular fragments of the 
same basic rock included in the granitite. 
Some of the crags of basic rock are traversed by veins of the 
granitite, which thin out and become finer towards the circum- 
ference of the mass. 
