Vol. 68.] KEUPER MAKLS AROUND CHARNWOOD. 29S 



to find, because the Keuper escarpment, since its initiation, had been 

 retreating eastwards; but shore-line phenomena occurred in the 

 Waterstones near Nottingham. 



The ' skerries ' were in many respects similar to those described 

 by the Author ; but, as the speaker recently pointed out, sometimes 

 contained as much as 50 per cent, of dolomite. An interesting point 

 was the occurrence of aeolian sand, in a ' skerry ' exposed 20 miles 

 east of the nearest Carboniferous outcrop. In upward succession 

 it was common to find a 'skerry' — with salt-pseudomorphs upon its 

 under surface — followed by sandy and dolomitic shales, which pass 

 upwards into the finer marls. He suggested that the dolomite 

 rhombs, precipitated from solution, were swept along with river- 

 borne detritus and deposited as ripple-marked and current-bedded 

 sandstone, similarly to the sandstones described by Sorby. The finer 

 detritus settled later, but a large portion of the marls might consist 

 of wind-borne dust, blown off the land. The term ' prevalent winds ' 

 seemed unfortunate, since monsoon conditions may have obtained^ 

 and the winds, during a large portion of the year, might have been 

 blowing inland. 



Prof. BoTD Dawkins complimented the Author on the detailed 

 and interesting nature of his communication, but was not at all 

 satisfied that the desert conditions of the Trias were those which 

 are usually associated with the idea of a desert. In all his ex- 

 perience he had found it difficult to get any microscopic slide of 

 sandstone which did not contain rounded grains. The marls, etc. 

 described by the Author as being ripple-marked were undoubtedly 

 deposited under water, as was indeed the main mass of the Trias. 

 The existence of worm-tracks therein also told against its desertic 

 origin sensu stricto. The occurrence of dreikanters proved no more 

 than did the presence of enormous numbers of dreikanters in recent 

 deposits in ISTew Zealand. The speaker finally referred to the minute 

 structure and varied mineral constituents of the marls, and said 

 that he did not for a moment deny the presence of a large amount 

 of wind-borne sand in the Trias. 



Mr. H. H. Thomas, in adding his congratulations to those of 

 previous speakers, asked permission to call attention to a somewhat 

 unimportant point. He cautioned the Author not to pay too much 

 attention to the spherical form of garnets — for the speaker had met 

 with heavy residues, from the Old Eed Sandstone and other deposits 

 in South Wales, consisting largely of minute idiomorphic garnets 

 which the least attrition would render spherical. It had been 

 suggested by a previous speaker that certain minerals, such as rutile, 

 tourmaline, etc. had been derived from older deposits. That was 

 possible for these minerals, but not so for a mineral like staurolite, 

 which the speaker had never detected in any pre-Triassic sediment. 

 Dr. C. A. Matley, in joining in congratulations to the Author, 

 stated that his own experience of the Keuper Marls was mainly 

 confined to Warwickshire, where no masses of older formations 

 projected through them as in Leicestershire. In the former county, 

 their widespread extent, combined with their fairly-constant thick- 

 ness and with the regularity of the intercalated sandstones, indicated 



