92 MR. E. W. BINNEY ON A DOLERITE 



through it ; still the breccia appeared to dip in the same 

 direction^ but at a much less angle, namely 25°, to a little 

 west of north. This is a very interesting fact to prove; 

 for if the rock graduates into the breccia, it would appear 

 to be of Permian age, and most probably a melaphyr ; but 

 if it is intrusive, as the evidence on the whole appears to 

 prove, all we can say is that it is of later date. 



This breccia is composed of angular pieces of a fine 

 siliceous stone, of a pink colour, more resembling quartzite 

 than anything else, cemented together by small quartz 

 crystals, and containing minute quantities of protoxide of 

 manganese. The form of the fragments is very like that 

 of the rocks in the Permian breccia of Rougham Point, 

 near the mountain-limestone of Humfray Head, and there 

 consisting for the most part of the neighbouring mountain- 

 limestone ; but no limestone has yet been met with in the 

 Gleaston breccia as might have been reasonably expected ; 

 and the pink quartzite is a rock hitherto unknown in the 

 district. The Permian breccise, so far as my experience 

 goes, although sometimes containing volcanic ash, are com- 

 posed of the rocks now found in the neighbourhood where 

 they occur, and nearly always vary with the older geolo- 

 gical rocks of the district. The composition of the Glea- 

 ston breccia makes me hesitate in designating it as Per- 

 mian, as it may be some rock altered by the dyke. 



The rock, in its best state of preservation, is remarkably 

 hard, of a reddish brown colour, has a moderately straight 

 fracture, and a pinkish white streak, and its specific gravity 

 is 2'92. 



Three average samples of the rock were taken, two from 

 the north and one from the south side of the beck. All 

 of them were more or less decomposed by exposure to air 

 and moisture, but No. 26 much less than Nos. 23 and 24. 

 Professor Roscoe, on analysis, found their present chemical 

 composition to be ai? follows : — 



