TRIASSIC BRECCIAS AND CONGLOMERATES OF SOUTH DEVON. 73 



2. rine-grained schorlaceous granite from Exminster. This is the 



only example which gave rise to doubt. Macroscopically it 

 seemed a fine-graiDcd granite with a little mica and a fair pro- 

 portion of schorl. When sliced it suggested a possible clastic 

 origin, and as I felt unable to satisfy myself I obtained Professor 

 Bonney's ever-ready help ; and he pronounces it a fine-grained 

 granite, probably from a vein or small boss. Also precisely 

 identical with Dartmoor varieties. 



3. In a quarry at Exminster there occur small patches of granitic 



material, quartz, kaolin, and mica, which are clearly the relics 

 of decomposed granite fragments ; and verj'^ similar looseness of 

 texture may be observed in granitoid remnants elsewhere. 



4. A comparison of sand from the Trias at Heavitree with modern 



sand from the bed of the Teign at Chagford (both given me by 

 Mr. Vicary) shows the following results : — Heavitree : felspar 

 fragments, including Murchisonite ; quartz-grains, many of the 

 smaller fairly rounded ; granitoid rock, with schorl ; grit, slate, 

 Lydian stone ; felspathic trap (andesite ?) ; colour ruddy. 

 Cliagford : Bulk of the material essentially identical with that 

 of Heavitree, but less rounded and not iron-stained ; quartz ; 

 felspar; felsite ; schorlaceous granite ; a little slate and grit; 

 mica : it chiefly differs from that from Heavitree in the plain 

 presence of mica and the absence of felspathic trap ; while slates 

 and grits are naturally more plentiful at Heavitree than at 

 Chagford. 



11. Eelsite Group. 



These rocks afford the widest range of variation, and are far 

 more plentiful than the true granites. I include under this head all 

 the granitoid fragments, seeing that most of the varieties pass easily 

 into each other, but divide them into schorlaceous and non-schor- 

 laceous. 



A. Non-ScJiodaceous. 



1. Pegmatite, apparently vein. Quartz, with some well-crystallized 



felspar. Teignmouth. 



2. Quartz-felspar vein, with decayed mica and kaolinized felspar. 



Exminster. 



3. Reddish quartz-felspar rock, like a Dartmoor vein-stone. Teign- 



mouth. 



4. Glassy quartz-felsite, reddish grey. Undistinguishable from some 



Dartmoor elvans. Teignmouth. 



5. Grey spherulitic felsite, with porphyritic quartz, slightly 



vesicular ; some cavities lined with crusts, some filled with 

 kaolin. Under the microscope the spherulitic structure is well 

 marked. Teignmouth. 



6. Grey quartzose rock of trachytic aspect, of somewhat porous 



texture ; base appears like an open granular felsite ; contains 



