294 THE KEUPER MAELS AROUND CHAENWOOD. [Juiie I9I2. 



regularity of deposition ; while the presence of marine mollusca at 

 the base of the Upper Keuper Sandstone of Warwickshire pointed 

 to at least one invasion of the sea in that area. He had not 

 found worm-tracks in this formation. He had found dreikanters 

 as surface-specimens in the ]Marl country near Birmingham, and 

 those exhibited, he thought, might well be of Drift, and not of 

 Triassic age. 



Mr. E. E. L. Dixon referred to a number of dreikanters on exhi- 

 bition which he had picked up on the surface near Lichfield, where 

 they appeared to be numerous. He had thought that they might 

 have been derived from adjacent Triassic outcrops, either directly 

 or by way of Glacial Drift ; but, unless such derivation were satis- 

 factorily demonstrated, he was prepared, after hearing the previous 

 speaker's remarks, to accept the view that they were chiselled 

 during a dry epoch of the Pleistocene. 



Prof. W. J. SoLLAs remarked that this paper would lead to more 

 definite ideas of what was intended when speaking of the Upper 

 Keuper as a desert formation, especially as to what parts of it were 

 subaerial, and what subaqueous, deposits. Pdpple-marks were 

 equally well-developed in each kind of deposit. The rounding of 

 sand-grains was a subject that still required investigation; such 

 rounding was far from universal in sandy deserts. In addition to 

 the rounded garnets already mentioned, attention might be called 

 to the rounded blebs of quartz which occurred in some of the 

 quartz-felsites of the Midlands ; on the other hand, the rounded 

 grains of other minerals — such as staurolite, tourmaline, and rutile, 

 furnished unimpeachable testimony to aeolian action. As to the 

 prevalence of desert conditions during the Upper Trias in England, 

 the evidence was cumulative and, to his mind, convincing. 



The AuTHOE, thanking the Eellows for their attention to his 

 paper, said that he had apparently- been misunderstood on several 

 points. In this paper not one single seam in the Upper Keuper 

 had been attributed to aeolian deposition. Both red and grey 

 bands were deposited under water — the former in lakes of standing 

 water, and the latter by shallow inflowing waters from the sur- 

 rounding hills. Nevertheless, some of the materials evidently had 

 undergone aeolian corrasion ere finally coming to rest. In the case 

 •of the garnets, it was not so much their spherical shape — indeed 

 many were very irregular-^, but the character of their surfaces to 

 which attention had been called. 



Every grey band bore witness to the existence of dry land in the 

 desert basin. These thin seams of coarse current-bedded sediment, 

 brought from a distant source, could not have been extended intp 

 the centre of the area at a time when it was occupied by standing 

 water. The coarse sand in a grey band was commonly followed by a 

 thin seam of quartzose dolomite, rippled and bearing salt-pseudo- 

 morphs. Such seams would be formed when the newly-arrived 

 water-spread dried up. Many grey bands contained several alterna- 

 tions of such seams. 



In his paper it was never suggested that any ripples had been 

 formed dry, but that they were produced in these shallow water- 

 spreads during their desiccation under the control of wind. 



