Vol. 59.] TKIASSIC PEBBLES OF SOUTH DEVON, ETC. 311 



23. 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., F.G.S. (Read April 8th, 

 1903.) 



Contents. Page 



I. Previous Investigations 311 



II. The Budleigh-Salterton Pebble-Bed 314 



III. The Cres de May of Normandy, and its Associated Rocks... 318 



IV. The Bunter Conglomerate of the Midlands 323 



V. The Palaeontological Evidence 325 



VI. General Conclusions 328 



The strongly-marked character of the pebbles of the Bunter and 

 the wide dispersal of so many of them in our old river-gravels have 

 caused a considerable amount of speculation as to their origin. 

 The subject, however, appears to me to be not yet exhausted ; and 

 this must be my apology for adding another to the long list of 

 papers connected therewith. 



I. Previous Investigations. 



The first attempt to deal with the subject in a systematic way 

 was in a paper on ' On the Pebble-Beds of Budleigh Salterton,' by 

 W. Vicary & J. W. Salter, which appeared in the Journal of this 

 Society for 1864. 1 In this important paper Salter came to the 

 conclusion that the fossils found in the Budleigh-Salterton pebbles 

 were not British types at all, but must be referred to the May 

 Sandstone and the Gres Armoricain of Normandy. He did not, 

 however, deal with all the material submitted to him, and admitted 

 the existence of ' possibly Devonian ' forms. 



In 1867 the Be v. P. B. Brodie 2 drew attention to the lithological 

 and palasontological resemblance between certain pebbles found in 

 the Drift of Warwickshire and others in the Budleigh-Salterton 

 Pebble-Bed. 



In 1869 3 Thomas Davidson completed the work of J. W. Salter 

 by showing that many of the Budleigh-Salterton pebbles did contain 

 Devonian fossils (brachiopoda). He was inclined to look to some 

 tract of land now occupied by the English Channel for the source 

 of the pebbles. 



In the same year appeared the Geological Survey Memoir on 

 ' The Permian & Trias of the Midland Counties/ in which Prof. Hull 

 suggested that the Bunter Conglomerate of the Midlands was an 

 ancient ' Northern Drift ' derived from the waste of the Old-Red- 

 Sandstone Conglomerates in the Scottish area. He indicated the 

 north or north-east as the probable direction from which they were 

 brought, and the agency as marine. This view, however, he 

 subsequently abandoned in favour of a more local derivation. 



1 Quart. Journ. Geol. Soc. vol. xx, p. 283. 



2 Ibid. vol. xxiii, p. 208. 



3 Ibid. vol. xxvi (1870) p. 70. 



