312 STR. HOWAED TOX OX THE 



Fig. 4. — TJie " Quadrant" Island^ as seen from the south-east. 



A 





The black bands represent porphjritic basic dykes cutting the gneiss. 



Fig. 5. — The " Quadrant " Island, as seen from the north-north-ivest. 



N. h S- 



The black bands represent porphyritic basic dykes, a, northern dyke cut off by cleft 

 h, southern dyke traversed by tliin gneissic vein. 



is faulted below as seen in fig. 6, and resumes its normal diP* 

 The " Quadrant" is composed mosth^ of somewhat coarse gneiss, 

 but also of granulitic gneisses and of apparently transition-rocks 

 intermediate between granulitic and actinolitic schists. From the 

 top it appears to be conformable with the Lizard Head schists. 



The rocks exposed at low water north-east of the narrow channel 

 called Quadrant Drang are known as the " Quadrant Shoals." They 

 are accessible from the mainland at extreme low spring-tides and 

 are conformable with the Lizard Head rocks. Their composition is 

 more basic than that of the '' Quadrant." A dyke two feet wide 

 similar to those on the " Quadrant " cuts the south-west rocks of 

 these shoals. 



Xorth-east of the " Quadrant Shoals " we have " Canker Drang," 

 which is covered with boulders and is dry at spring- tides, and on 

 the north-east of the Drang we have the " Canker ledges," The 



