338 Professor T. G. Bonney — Desert Conditions in the Trias. 



seolian deposits, before we can determine what parts wind and water 

 have respectively taken in making this member of the Trias. Here, 

 however, I may remark that neither Professor "Watts nor Mr. Walcot 

 Oibson was the first ^ to observe that in the Charnwood Forest region 

 the Keuper fills up hollows in the older rocks. 



This, however, is a small matter, like all questions of priority, so 

 I pass on to the points in regard to which I cannot wholly agree with 

 Mr. Lomas. The following extract from his paper may serve as 

 a summary (p. 196): "The pebble beds of the Midlands, although 

 originally of fluviatile origin, do not exhibit the characteristics of river 

 action. The individual pebbles show no orientation in the arrangement 

 of their longer axes, but are wedged together in a tumbled mass as if 

 they had dropped into their present situations by the removal of material 

 about them. The insecurity of their positions is evidenced by the 

 pitting which has resulted from their successive readjustments. The 

 interspaces between the pebbles ai'e almost free from sand, but 

 lenticular seams of sand occur, which may have been protected from 

 removal by wind, when the pebbles formed a continuous covering. 

 There are places in our own district where it does not appear that 

 concentration took place, and the sand with pebbles marking the 

 situations of temporary streams still persist as originally laid down." 



Of these points I will take the pitting first, since it needs only 

 a brief notice. As the depressions, though generally very shallow 

 on hard quartzites, may be almost a quarter of an inch deep, and 

 cori'espondingly large on mudstones, they must have been rather 

 slowly formed (compare those on the pebbles in the similar but 

 indurated deposits of the Swiss nagelfluhe). Hence I should regard 

 them as more probably indicative of a long and continuous pressure 

 (often associated with solution -) than of one successively applied to 

 new parts. Moreover, the readjustments demanded by Mr. Lomas 

 must be brought about by the withdrawal of material from below, 

 for we cannot suppose the impression to have been made during the 

 brief time when the pebbles in any one layer were exposed (in simple 

 contact, without an overlying weight) to the action of the wind. 

 Such withdrawal could perhaps be effected by subterranean water 

 washing away the finer material from some underlying gravel, but, 

 as will be seen, I have found no real evidence that this has actuallj^ 

 occurred, and it would give no help to Mr. Lomas' hypothesis. 



The other points may best be answered by a brief summary of 

 observations made last December at three places on Cannock Chase in 

 order to verifj- my recollections of past work,^ and study some sections 

 in the light of this new interpretation. As my time was necessarily 

 short, I selected three places sufficiently far apart to be fairly 

 representative of the whole district. One was at the top of Style 

 Cop, another near Baland's Pool (by the road from Eugeley to 

 Hednesford), and the third on the Satnall Hills. The first was about 



' Lomas, itt supra, p. 184, cf. 193. See Hill & Bonney, Quart. Journ. Geol. 

 Soc, vol. xxxiii (1877), p. 754. But it was also noticed bv earlier writers. 

 2 See T. Mellard Eeade, Geol. Mag., 1895, p. 341, and" Plate XI. 

 •* Since 1895 I have but seldom visited this moorland. 



