part 4] MATERIAL OF BUXTEll PEBBLE-BEDS. 337 



From the foregoing statements it is evident that the bulk of the 

 material in question was most likely derived from Scottish sources ; 

 that the Pennine ridge has certainly suppHed a share ; and that 

 subordinate currents have probabl}'^ contributed their small part 

 towards forming the Nottinghamshire Pebble-Beds. 



I gratefully acknowledge the obligations that I owe to many 

 for their kind assistance in connexion with this paper, especialh' 

 to the Eev. Prof. T. G. Bonney, Prof. H. H. Swinnerton, and 

 Dr. H. H. Thomas. 



Discussion. 



Dr. li. L, Sherlock thought that it was not clear what was 

 meant by the 'Northern Bunter basin.' This might be either west 

 or east of the Pennines. In either case it would be necessary for 

 the north-western river to cross the Pennine ridge, admittedly in 

 existence. Onl}^ in times of flood did the river bring sediment 

 through the hills into Nottinghamshire, and yet the bulk of the 

 material was believed by the Author to come from Scotland. The 

 speaker thought that a more local origin for the bulk of the 

 material was probable, and that, until the Carboniferous rocks of the 

 Pennines, and particularly the Millstone Grrit, had been searched, 

 it w^as unsafe to assume that the heavy minerals could not have 

 been obtained locally. One objection to the theory that the bulk 

 of the Bunter material was brought from Scotland had never been 

 answered — it was, that the number of pebbles fell off as the supposed 

 source was approached. The speaker believed that the paper by 

 the late J. Lomas on the Origin of the British Trias explained 

 satisfactorily most of the features of Triassic rocks. On this 

 hypothesis, supported by the work done by the Egyptian Survey, 

 Dr. Wade, and others, the Bunter Pebble-Beds were formed by 

 torrential waters that occasionall}^ swept out wadis, filled with 

 debris produced by desert erosion, and spread the materials over 

 a coastal plain at the foot of the hills. The rock-fragments 

 were not onh^ rounded by mutual battering, but much line silt 

 \vas produced which, when dry, was blown into pools and into the 

 Caspian-like sea to form Triassic marls. The chief difficulty was 

 the presence of quartzite-pebbles, but it was possible that these 

 might not have travelled far : say, from the buried pre-Triassic 

 rocks of Charnwood Forest. The quantity of pebbles in the 

 Pebble-Beds of Nottinghamshire was apt to be exaggerated, because 

 they were concentrated in soils and Drift, although in a clean 

 section there were usually quite few stones. Moreover, only a 

 moiety of these were quartzite. 



It appeared from a lantern-slide that the Author had not 

 discriminated between the divisions of the Bunter. There are beds 

 in the Lower Mottled Sandstone which have a structure different 

 from that of the Pebble-Beds, and the former were laid down in 

 very shallow water. The sands at Whisker Hill, Retford, one of 



Q. J. G. S. No. 292. 2d 



