THE GEOLOGY OF THE ENGLISH CHANNEL. 125 



M. 36e. S. 37 V/. Edd., 17-5 miles. 



Sub-conchoidal fracture. A dull purple rock, with parts more drab 

 in colour, flesli-tinted felspars in a horny matrix. 

 M. 35d. S. 32° W. Edd., 18 miles. 



Grey, with warm tinge, purple mottling, sub-conchoidal fracture, 

 minute flesh-tinted felspars, mostly much decomposed. 

 M. 20a. S. 25° W. Edd., 20-5 miles. 



Compact rock, very like o54/3d. in general appearance, but without 

 the small black grains and the calcite. Eather harder than that rock. 

 Grey in colour with warm tinge. Small flesh-coloured felspars, many 

 of which are decomposed. 

 M. 21b. S. 25° W. Edd., 21*2 miles. 



Compact light grey-drab felsite, red mottling, porphyritic quartz. 



Crypto-crystalline felsitic ground-mass, in which porphyritic quartz 

 is freely developed; the crystals, although rounded at the angles and at 

 places invaded by tlie felsitic matter, are largely bounded by straight 

 lines. Minute fluid inclusions are not uncommon, but comparatively 

 the quartz is clear. The felspars are almost formless and ill differen- 

 tiated from the ground-mass ; micro-perthite is indicated in some 

 individuals. There is a small yellow patch of some granular mineral 

 showing brilliant colours between crossed nicols. This same mineral 

 is also sometimes associated with the dusty, somewhat dendritic red 

 oxide of iron which gives the rock its mottling. 



M. 62c. S. 25° W. Edd., 46-4 miles. 



A green-grey compact rock, with much quartz and fels; ar irregularly 

 distributed. The felspar is pink. The porphyritic constituents more 

 prominent than in any of the preceding. Calcite is freely developed 

 on joint faces. 



The third group would appear to bear a close relation to the 

 granites which form a prominent feature of the lithology of parts of 

 this area. In this respect they probably stand much as the very hard 

 India-red felsite so freely found on the Hallsands Beach does to the 

 granites of Dartmoor. All are horny in texture and have a sub- 

 conchoidal fracture. 

 M. 12f. S. 28° W. Edd., 17-8 miles. 



No detailed notes taken of this rock. 

 M. 72d. S. 23" W. Edd., 19 miles. 



India-red, compact felsite, occasional small red felspars. 

 M. 9a. S. 31° W. Edd., 21-7 miles. 



Eed felsite. Green porphyritic felspars, compact texture. 



Ground-mass crypto-crystalline. Felspars much decomposed, the green 



