BUDLEIGH-SALTERTON PEBBLE-BED. 333 



rock in question is a tough coarse quartzite, white, light-grey, or light-yellow, and 

 abounding in internal casts and impressions of the exterior of Orthis Berthoisi, var. 

 crratica, but these are almost always more or less out of shape, and somewhat com- 

 pressed. At Budleigh-Salterton we do not, as far as I am aware, meet with pebbles of a 

 similar nature ; on the contrary, that fossil has generally preserved its natural shape. I 

 would not, therefore, point to that rock at St. Germain-sur-Ille as a possible source of 

 derivation for the Budleigh pebbles. It is in pebbles referred to the age of the " Gres 

 de May" that we find at Budleigh-Salterton the larger number of Lower-Silurian 

 Brachiopoda ; but for all details regarding Lower-Silurian sandstones and qunrtzites and 

 their fossils, as well as those from the " Gres Devonien " or Lower-Devonian sandstones 

 of Normandy and Brittany, I must again refer the reader to the able memoirs of 

 M. Gaston de Tromelin and M. Lebescontc. 



Above the Silurian formation already described we find the lower divisions of the 

 " Etage Devonien a Orthis Monnieri " of Tromelin ; and here we also find large deposits 

 of sandstones of different degrees of compactness, as well as of colour, whitish-grey and 

 yellow, often ferruginous, being the prevailing colours ; and these agree completely with 

 the pebbles assigned to that period that occur at Budleigh-Salterton. Many of the 

 same fossils, and in the same condition of internal casts and external impressions, occur 

 in the pebble of one, and the rock of the other country. Orthis Monnieri, Rouault, = 

 0. Vicaryi, Dav., being thus found both in Brittany and at Budleigh-Salterton, rocks 

 similar to these above mentioned must have furnished the great mass of Devonian pebbles 

 accumulated on the South-Devon coast, and for many miles inland. 



I need not enlarge further upon this possible source of derivation, as another may 

 perhaps have existed at one time and nearer our shores. 



4. The assumed Mid-Channel Source of Derivation. 



It has been clearly shown that there exists on the other side of the Channel sand- 

 stones and quartzites in situ, which entirely agree in colour, composition, and organic 

 contents with that of the Budleigh-Salterton pebbles. It has been suggested by several 

 geologists that an extension of the same rocks may have existed in some parts of the 

 Channel area between the coast of France and that of South Devon, and that from thence 

 the pebbles now accumulated in Devonshire may have been derived by denudation. 

 This view of the case has been entertained and expressed by Prof. Ramsay and others ; 

 and it certainly bears with it some degree of possibility, and even probability, although 

 it cannot be demonstrated by any direct evidence. 



Mr. Ussher thinks that the stratigraphical evidence would bear also in that direction ; 

 and in a letter he wrote to me on the 30th of August, 1879, he says: — "As to the 

 Gorran Haven, or rather to an extension (formerly) of Gorran Rocks Channelwards, if 

 your investigations lead you to that source, there is nothing against it, inasmuch as the 



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