88 GEOLOGY OF THE GREAT CENTRAL RAILWAY. [Feb, 1 899, 



and south of its range. The Author's results showed that it was 

 much more like the Lias as seen in Yorkshire than as seen at 

 Cheltenham. He also drew attention to the collections of small 

 ammonites referred to by the Author as occurring on certain 

 horizons : such collections were not always on the same horizons, 

 or of the same species. They were the fry of larger ammonites, 

 known or unknown, and were scarcely worthy of a name. Speaking 

 generally, he did not think that one in ten of all the ammonites 

 that had ever been collected anywhere were full-grown. 



Mr. A. E. Salter said that four distinct Boulder Clays are 

 mentioned, all of which seem to be characterized by the absence of 

 boulders. In recently traversing the district covered by the paper, 

 he had been struck by the different character of the Drift-deposits 

 as regarded their relation to older drifts, their contained erratics, 

 and their height above Ordnance datum, when compared with those 

 found south of the Chalk escarpment. He would be glad of further 

 information as to the mode of origin of the contortions in the brown 

 clays, and the source of derivation of the chalk in the chalky clay ; 

 also as to whether there were other and related drifts at higher 

 levels, and whether there was any great difi'erence in the derived 

 fossils or erratics contained in the various clays. 



Prof. Watts referred to the existence of ' infant-mortality beds ' 

 in rocks at several other horizons, as well as in the Lias. Thus 

 in the Bala Beds there is a zone characterized by minute trilobites, 

 and the Wenlock Shales and Tarannon Shales are marked by minute 

 brachiopods. 



Mr. E. S. Herries stated that he had had the advantage of 

 going over most of the ground with the Author, and congratulated 

 him on his paper. He wished to know whether the Author had 

 any views as to the source of origin of the chalk which went to 

 form the Chalky Boulder Clay of the district described. 



The President also spoke. 



The Author, in reply to Mr. H. B. Woodward, said that 

 whereas the great Chalky Boulder Clay of the districts that he knew 

 occurred above the so-called 'Mid-Glacial' gravels, the brown 

 contorted Boulder Clay near Rugby certainly occurred below these 

 gravels, although it contained chalk in abundance in places. 



The Author agreed with the Rev. J. P. Blake in his suggestion that 

 the fauna of the Lower Lias of JSTorthamptonshire and Warwickshire 

 agreed rather better with that of Yorkshire than with those of 

 districts to the south-west, but he did not think that the specimens 

 of Ammonites 2'^oli/morphus, A. trivialis, and A. bifer were immature. 



In reply to Mr. Salter, he said that the subject of the probable 

 origin of the contortions in the brown Boulder Clay had been discussed 

 elsewhere (Proc. Geol. Assoc, vol. xv, p. 430), and that he had never 

 yet been able to form a clear idea of the conditions capable of pro- 

 ducing in these districts Glacial deposits, made up in cue place 

 chiefly of Oxford Clay, in another of Kimeridge Clay, in another to 

 a considerable extent of Carboniferous and other old rocks, but 

 always associated with chalk and flints. 



