164 THE CLAY-WITH-FLINTS. [May I906, 



typical Clay-with-Flints. On the North Downs the movement of 

 these superficial beds was still going on, and they were still to a 

 certain extent being added to by the slow weathering of the existing 

 outliers of the Tertiaries. With a higher water-level this was more 

 rapid, and evidence of the extent of this denudation might be indi- 

 cated by a bed of practically-clean unrolled flints in one of the 

 dry valleys running northward from the edge of the Downs, which 

 could not have been transported far, but for which the water- 

 action was enough to carry away the clay wherein the flints were 

 embedded. 



Mr. Whitakee, who read the paper for the Author, prefaced his 

 reply by alluding to his own connection with the Clay-with-Flints, 

 which began in Berkshire, during the early days of his work on 

 the Geological Survey. He was much troubled by the deposit, 

 then little known, and at one time despaired of understanding it ; 

 but his depression was cured on finding that some of his senior 

 colleagues had been led astray by this clay. The name used was 

 unwittingly the same as that given by French geologists to a like 

 deposit in France (argile a silex), and it was coined after- 

 work in Berkshire. That work was extended into neighbouring 

 counties, and a theory of origin was then advanced. Later on, 

 the work of mapping the Clay-with-Flints was greatly extended 

 by the Geological Survey, both on the northern and southern 

 sides of the London Basin, on the old series of maps. Still later, 

 other tracts were surveyed, and the results published on the new 

 series of maps; and it was to these tracts that the paper chiefly 

 referred. 



To Prof. Dawkins he replied that, while of course it was possible 

 that some London Clay might have found its way into the deposit, 

 in the area specially described by the Author the Reading Beds 

 were generally a thick mass of clay, quite enough to account for so 

 thin a deposit. 



The answer to the Rev. E. Hill's query as to East Anglia, was 

 that there was practically no representative of the Clay-with-Flints 

 there, the occurrence of a wide and thick mass of Boulder-Clay 

 having made its formation difficult, on any theory of origin. 



As to Prof. Sollas's Clay-with-Flints over Eocene sand, Mr. 

 Whitaker said that he should like to see the deposit, for he might 

 be disposed to classify it otherwise. 



Mr. Kennard's objection concerning the bringing-in of the 

 Glacial Period, already called in to account for the gravels of the 

 valleys, was met by the reminder that it was not the Author who 

 had so called it in. Mr. Whitaker thought that the gravels in 

 question might be post-Glacial, and so perhaps did the Author. 



In conclusion, Mr. Whitaker considered that the Author had 

 made out a good case, at all events so far as concerned the tract to 

 which his remarks were chiefly confined, and he hoped that further 

 investigation would be made in other areas, where there was a 

 difference in the relations of the Clay-with-Flints to the Eocene 

 Beds. He was always ready to learn from younger workers, who 

 of course had the advantage of later information. 



