Probtihle Source of Pehbles of South Devon. ."i-il 



miles ill Northern Cornwall, extending from the coast eastward 

 towards Camelford Station and St. Clether. In the eastern part it 

 extends to the neighbourhood ot the Brown Willy mass of granite, 

 while on the north it approaches the boundary between the Lower 

 Culm and the Upper Devonian. The rocks described are ot the latter 

 age. and contain Spirifera disjuncta. 



Except in the southern coast-region (Tintagel and Trebarwith 

 Strand) the strike is fairly uniform in an east-south-easterly and 

 west-north-westerly direction, the beds having a northerly dip : but 

 north and south of Tintagel Head the higher members appear, 

 greatly faulted, being brought in out of their true position partly 

 by a change of strike, partly by dip-faults. The most distinctive 

 rocks, utilized as a datum for mapping, are a group ot ashes 

 and lavas. The latter are often amygdaloidal, and possess original 

 characters which are still recognizable : but the whole group is 

 frequently much altered or entirely reconstructed, with the formation 

 of epidote (sometimes enclosing allanite). sphene, biotite. chlorite, 

 etc. The rocks are associated in many instances with calcite. at 

 least partly due to contemporaneous deposition, but frequently 

 forming a corporate part of the renovated rock, and the mineral 

 is found with quartz and translucent felspar. 



Bluish-black slates and fine laminated qiiartzose beds overlie and 

 underlie this volcanic series. 



The remaining rocks are phyllites, closely resembling those from 

 the Ardennes. The author divides them into four groups. The 

 highest of these (Tredorn Beds) overlies the uppermost division of 

 the Blue-Black Slates, and in the western part of the district con- 

 tains a mineral forming small white spots, not yet determined. 

 The beds underlying the Lower Blue-Black Slates (Hallwell Cottage 

 Beds) are banded phyllites, with quartzose laminae, typically con- 

 taining abundant crystals of clinochlore with a habit resembling 

 that of ottrelite. The underlying phyllites (Penpethy Beds and 

 Slaughterbridge Beds) contain no distinctive mineral. Taken as a 

 whole, the phyllites consist of a sericitic and cbloritie groundmass 

 containing unorientated crystals of white mica, micaceous ilmenite, 

 haematite, and minor quantities of tourmaline and rntile. 2sorth- 

 east of Camelford (Grigg's Down) they furnish clear evidence of 

 contact-metamorphism. 



April Sth.— J. J. K. Teall, Esq., :^[.A., FR.S., Vice-President, 

 in the Chair. 



The following communications were read : — 



1. ' On the Probable Source of some of the Pebbles of the 

 Triassic Pebble-Beds of South Devon and of the Midland Counties.' 

 By Octavius Albert Shrubsole, Esq., E.G.S. 



After an account of previous researches on this subject, the author 

 proceeds to describe the Budleigh-Salterton Pebble-Beds. Judging 

 from lithological evidence, the bulk of the pebbles must have come 



