464 Notices of Memoirs — Mr. Htcdlesfon^s Address — 



By tlie Geological Survey this series has hitherto been mapped as 

 Trias, but in the new " Index Map " they are coloured as Permian. 

 There is no palseontological evidence which would connect them 

 with the fossiliferous Permians, usually regarded as of Palseozoic 

 age, but it has been evident for some time past that opinion was 

 inclining to revert to the views of Murchison and the older 

 geologists, more especially as to the position of the breccias so 

 largely charged with volcanic rocks. The subject was dealt 

 with by Sir A. Geikie in his address to the Geological Society, 

 where he speaks of some of these rocks as presenting the closest 

 resemblance to those of the Permian basins of Ayrshire and 

 Nithsdale.i 



One difficulty which presented itself to the Devonshire geologists 

 in accepting the Permian age of the ' red beds ' was, that the whole 

 of the lower Secondary rocks appeared as an indivisible sequence, 

 proved by its fossils to be of Keuper age at one end, and therefore 

 iuferentially of Keuper age at the other. Dr. Irving, however, 

 considered that at the base of the Budleigh Salterton pebble-bed 

 there is a physical break of as much significance as that between 

 the Permian and Trias of the Midlands. In the marls which 

 underlie this pebble-bed he recognized a strong resemblance to 

 the Permian marls of Warwickshire and Nottinghamshire ; and 

 Professor Hull, who had been studying the sections east of 

 Exmouth about the same time, ultimately acceded to this view.^ 

 Its acceptance by the Survey thus throws all the Exmouth beds 

 into the Permian ; and that formation, according to the new reading, 

 has an outcrop of some 35 miles from the shores of the English 

 Channel to within 3 miles of Bridgewater Bay. The fertility of 

 these red clays, loams, and marls has long been recognized by 

 agriculturists, and it is not improbable that the abundance of 

 contemporaneous volcanic material may in some measure have 

 contributed to this result. 



In conformity with the new mapping, the Budleigh Salterton 

 pebble-bed and its equivalents to the northwards are accepted as 

 of Bunter age, and thus constitute the base of the Trias in the 

 south-west. Like most pebble-beds, they are irregularly developed 

 between the Permians and a strip of reddish sandstone (coloured 

 as Keuper), which runs up from the mouth of the Otter to within 

 a short distance of Bridgewater Bay. The materials of the pebble- 

 beds are not of local origin, like so much of the breccia at the base 

 of the Permian. The general resemblance, both as regards scenery 

 and composition, to the Bunter conglomerate of Cannock Chase has 

 been pointed out by Professor Bonney, who seems prepared to 

 endorse the recognition of the Budleigh Salterton pebble-bed as 

 a Bunter conglomerate. He was not impressed by any marked 

 unconformity with the underlying series. To some extent we may 

 accept this view, since whatever may be the age of the Devonshire 



1 Quart. Journ. Geol. Soc, vol. xlviii (1892), p. 161. 



2 Cf. Irving, Quart. Journ. Geol. Soc, vols, xliv (1888), p. 149; xlviii (1892), 

 p. 68; and xlix (1893), p. 79; and Hull, op. cit., vol. xlviii (1892), p. 60. 



