Vol. 59.] SOUTH DEVON AND THE MIDLANDS. 329 



as high as the Alps x ; anyhow, it must have been drained by some 

 large river or rivers, and we know that a vast amount of sediment 

 has been removed. Whither has that sediment gone ? There are no 

 local deposits that adequately account for it. There are Triassic rocks 

 in Normandy, but they are of Keuper age. There are also pebbly 

 sands which occur as a fringe around the old rocks, and are considered 

 to be in part of Triassic age ; but their extent is insignificant. 



Now, why should not the drainage of that Armorican plateau 

 have been in part at least northward ? Many considerations 

 render this probable. The Budleigh-Salterton Pebble-Bed, perhaps, 

 may be thought to prove it ; but if it prove that, it can suggest 

 much more. And, therefore, I conclude that, whether the 

 Budleigh-Salterton pebbles are exactly contemporaneous with 

 the Bunter pebbles of the Midlands or not, the latter to a large 

 extent represent the waste of the old Armorican plateau or the 

 land connected therewith. (See map, fig. 2, p. 330.) 



And this brings me to the question of the particular agency 

 by which the pebbles were dispersed. I do not propose to discuss 

 that question at length, as it has been so fully dealt with by 

 Prof. Bonney in his various papers, which have, as it seems to 

 me, made the old view which regarded these pebbles as a marine 

 shingle-bank or beach-deposit practically untenable. 



Let us, then, see how the theory ot the fluviatile origin of the 

 Bunter pebbles fits in with our facts. The facts, however, would 

 remain in any case. 



It is not pretended that we have any distinct evidence that the 

 arenaceous beds of the Bunter have been derived from the waste 

 of the Armorican land ; but it is a possibility which it would 

 be well to have in view, and there are some considerations which 

 suggest it. When, however, we come to the pebbles suddenly 

 intercalated in the sandstone, we may well ask by what agency 

 they were brought, and under what conditions. 



The Keuper is usually considered to have been a lake-basin ; and 

 it is difficult to conceive of the Bunter otherwise than as representing 

 an initial stage in the same movement of depression — a lake-district 

 fed at least by one great river from the south ; but having too 

 small a rainfall to enable it to take up much local material. 



To account for the sudden appearance of the pebbles, we must of 

 course find a sufficient cause. Some strong force must have moved 

 them, so that they finally came to rest where only finer sediment 

 had previously found its way, whatever may have been the 

 direction from which the lower sandy beds came. It is useless 

 to speculate on the precise cause of this change. It may have 

 been a reversal of drainage, or a change of atmospheric conditions. 

 Whatever it was, it must, if we accept the fluviatile hypothesis, 

 have been very energetic. 



While I suggest that the Devon pebbles may have been deposited 



1 Quart. Journ. Geol. Soc. vol. xliii (1887) p. 320. 



