130 DKEDGINGS OF THE MARINE BIOLOGICAL ASSOCIATION: 



DOLERITE. 



M. 14e. S. IT W. Edd., 20-3 miles. 



A fine-grained even -textured rock of a distinct green colour. Some 

 iron pyrites show in the hand specimen. Numerous lath-shaped 

 felspar microlites with irregular terminations, all quite fresh and clear. 

 Pale bluish-green fibrous hornblende is quite tlie most prominent con- 

 stituent of the rock ; there is no general direction pursued by its fibres. 

 Scattered closely throughout the section are very irregular grains of a 

 minutely granular pale brown mineral of strong double refraction when 

 examined with high powers and strong light. Dirty white by reflected 

 light, this is probably leucoxene. 



Curious little streams of (?) magnetite occur rather frequently, in 

 forms suggesting that they are reminiscent of some original prismatic 

 mineral. 



M. 16b. S. 29° W. Edd., 20-9 miles. 



Pale green minutely granular rock. 



A slide of confused texture. Fibrous green hornblende. Felspar 

 with a tendency to lath-shaped sections. Apparently no quartz. Grain 

 very fine. 



M. 21e. S. 25. W. Edd., 21 '7 miles. 



A close-textured grey rock, looks much like a grit. 



Tlie most prominent feature in the section is the abundance of pale 

 yellowish-green acicular or fibrous mineral in diverging bundles, 

 which often have the appearance of having been drawn together at the 

 middle. Here and there almost colourless, at other places this mineral 

 takes a blue-green tint, and it is almost certainly actinolite. These 

 bundles are largely set in a crypto-crystalline ground-mass, which is 

 freely invaded by shorter prisms of actinolite. There are also felspar 

 crystals of irregular outline, some certainly plagioclase, some possibly 

 orthoclase, and micro-porphyritic quartz is about as frequent as the 

 felspar. There is a considerable sprinkling of grains of titanic iron ore. 



M. 80c. S. 16i° W. Edd., 48-9 miles. 



Clouded white felspars, lath-shaped in part, in part conforming to 

 the interspaces between the augites which constitute the more part of 

 the rock. Portions of the felspars are still quite clear. The augite is 

 in the main quite fresh, but traces of chloritic products occur. 

 Characteristic patches of ilmenite. 



DIABASE. 



M. 27a. S. 19° W. Edd., 18 3 miles. 



Compact dark grey rock, green felspar and hornblende. Augite, 

 hornblende, chlorite, plagioclase, leucoxene, quartz. The augite, pale 



