442 



THE LONDON CLAY AND BAGSHOT BEDS OE ALDEESHOT. 



fail to take an interest. In consequence of the overwhelming evi- 

 dence obtained by Lieut. Lyons he accepted his conclusions and gave 

 up his own hypothesis with respect to the section on Redan Hill &c. 

 He had verified IVIr. Lyons's reading of that section, and observed that 

 the clays of the Middle Bagshots constituted the most persistent hori- 

 zon. Where there is a full normal development of London Clay we 

 have a passage into the Lower Bagshots. He was not quite prepared 

 to accept the calculation of 330 feet from the thickness of the London 

 Clay at the Aldershot waterworks. He regretted that we seem no 

 further advanced as to the age of the Kingsclere axis. 



Mr. Whitaker complimented Mr. Irving on having frankly ac- 

 knowledged his error when it was shown that he had been mistaken. 

 It would, however, be a gratification to him that the correction had 

 come from a former pupil. It was scarcely to be expected that 

 pebble-beds should be persistent over any area ; but it was often a 

 matter of surprise how certain thin beds occurred for long dis- 

 tances. He always felt under obligations to those who would 

 correct errors of detail, and hoped that this hint might not be lost 

 upon other officers. 



Mr. Monckton expressed his obligations to Mr. Lyons, whose 

 paper, in the main, confirmed the work of Mr. Hemes and himself. 

 One of their endeavours had been to ascertain if there existed 

 reliable physical differences between the Upper and Lower Bagshots. 

 In this he considered that they had been successful. The Lower 

 Bagshots are characterized by the presence of beds or layers of 

 pipeclay, by abundance of false-bedding, and an absence of shells ; 

 in the Upper Bagshots there is no false-bedding, an absence of pipe- 

 clay, and usually casts of shells. Applying these tests to the 

 Thorn-Hill — Redan-Hill section, the results were the same as those 

 arrived at from a surveyor's point of view. This work had been 

 admirably done. The clay at the top of Reclan Hill had not before 

 been noticed. 



Mr. Hudleston remarked that, since there was no opposition to 

 Mr. Lyons's reading of the district, it was unnecessary to say any- 

 thing more in corroboration of a most excellent and original paper. 



Mr. Herejes justified the account of the Thorn-Hill section given 

 by himself and Mr. Monckton, and observed that the clay on Redan 

 Hill was not exposed at the time their paper was written. He 

 had found Upper-Bagshot fossils in Beacon Hill, and also in abun- 

 dance on the steeple-chase course in the large outlier to the north, 

 thus confirming the Survey mapping. 



Mr. Lyons, in reply, cordially acknowledged the advantages he 

 had derived from Mr. Irving's training. Referring to the thick- 

 ness of the London Clay at the Aldershot waterworks, he showed in 

 detail how the thickness of 330 feet was obtained, and argued for 

 the correctness of his estimate. The extent of the Pebble-bed 

 was most remarkable, and the Geological Survey mapping was good, 

 although the boundaries might require to be altered a little. As 

 regards the passage-beds in the well-section, he did not speak with 

 certainty. 



