ANDESITES OF DEVONSHIRE. 499 



of ' felspathic traps ' iii the Dartmoor granite area from the fact that 

 in the Triassic (or Permian) breccias near " Dawlish and Teign- 

 mouth and thence to the southward " fragments known to be of 

 Dartmoor origin are associated with undoubted ' felspathic-trap ' 

 fragments. He says, " The fact that these fragments came from the 

 direction of Dartmoor, coupled with the absence of any locality 

 between Teignmouth and Dawlish and their vicinities and Dartmoor 

 whence they can have come, thus points directly to Dartmoor itself 

 as their source." 



The objections to this view appear to me very strong, namely : — 



1. It seems to be a non sequitur, as there is no necessity for 

 believing that the granitoid and ' f elspathic-trap ' fragments came 

 from one and the same area ; and there is plenty of ' felspathic trap ' 

 in place near Dunchideock, 7| miles north-west of Dawlish. 



2. Almost all the 'felspathic traps' being oli vine-basalts, they 

 cannot be the effusive equivalents of granite. 



3. No necks or dykes of ' felspathic trap ' are known to penetrate 

 the Dartmoor granite. 



4. It is highly improbable that the granite of the core and the 

 lavas of the surface of the supposed volcano were simultaneously 

 exposed to denudation. 



5. The alleged facts with regard to the existence of quartz- 

 porphyries among and also intrusive in the ' felspathic traps ' of 

 unclouhted Permian (or Triassic) age will be shown in a subse- 

 quent part of the present paper to be at least very doubtful. 



It is true that Mr. Ussher mentions a " quartz-porphyry giving 

 place upwards and outwards to a rock resembling a mica andesite " ^ 

 associated with the Thurlstone New Red outlier, and Mr. Worth 

 himseK describes a " trachytic quartz-felsite " passing into a 

 " rhyolitic pitchstone " as occurring at Withnoe, in Whitesand Bay, 

 and " undoubtedly continuing to a junction in depth with the main 

 mass"^ of the 'trap' of the Cawsand New Red outlier, but the 

 evidence that these rocks belong to the same series as the ' felspathic 

 traps ' is not quite conclusive. 



ly. Intrusive Dykes in supposed New Red Trap near Plymouth. 



[Since the present paper was read, the writer has visited the 

 Plymouth district, and hopes shortly to be able to publish more 

 precise information on the subject.] 



Meanwhile the following notes, based on field observation only, 

 may be of interest. The main mass of the Cawsand rock is red or 

 piniish, and contains a good deal of brown mica. The evidence in 

 favour of its Permian (or Triassic) age is its macroscopical resem- 

 blance to some of the weathered olivine-basalts of that age (this is 

 not worth much) and the occurrence at Sandway Point (6-inch map, 



^ Op. supra cit. p. 249. 



2 ' Additional Notes on the Cornish Trias,' Trans. Eoy. Geol. Soc. Coniw. 

 1891, p. 338. 



