92 NATURAL SCIENCE. August. 



were older than the clays and sands of Bracklesham and the clays of 

 Barton. He subdivided the Bagshot Beds, and correlated with them 

 certain strata in Hampshire and the Isle of Wight. Subsequent 

 researches by Mr. Starkie Gardner, Mr. Monckton, and Mr. Herries, 

 have thrown doubt on the correlation of the Upper Bagshot Sands of 

 Surrey with those of Hampshire (the Headon Hill Sands) ; and in a 

 later work^ Prestwich agreed that the Upper Bagshot Sands of the 

 London area might be partly or wholly of Bracklesham age. Ready 

 at all times to accept corrections when assured of their accuracy, 

 he was also not unwilling to admit changes in classification when the 

 alteration was for the general convenience. Thus he adopted the 

 term Oligocene for strata previously grouped as Upper Eocene. He 

 did not, however, agree with Mr. Whitaker in his proposal to form a 

 separate division, termed the Oldhaven Beds, from strata in part 

 grouped by Prestwich with the basement-bed of the London Clay, 

 and in part with the Woolwich and Reading Series. 



Continuing his researches Prestwich described in full detail the 

 strata between the London Clay and Chalk, giving the names "Thanet 

 Sands " and "Woolwich and Reading Series" to strata previously 

 grouped together as the " Plastic Clay Formation." Referring to the 

 important series of Eocene memoirs, which he had completed in 1854, 

 Edward Forbes remarked, " These remarkable essays embody the 

 results of many years' careful observation, and are unexcelled for 

 completeness, minuteness of detail, and excellence of generalisation."* 

 A popular account of the Eocene strata and of the superficial 

 deposits that occur in the neighbourhood of London was given by 

 Prestwich in 1854 ^^^ 1856, in the course of three lectures on the 

 geology of Clapham, and these were published a year later under the 

 title of " The Ground Beneath Us." Clearly and pleasantly written, 

 this little work was well calculated to arouse the interest of the reader, 

 and at the time of its publication it was one of the best introductions 

 to geology which it was possible to place in the hands of a beginner. 



While Prestwich gave his attention in the main to pure science, 

 he did not neglect the important applications of knowledge. By his 

 publication in 1851 of "A Geological Inquiry respecting the Water- 

 bearing Strata of the country around London," he came to be recog- 

 nised as the leading geological authority on the subject ; and in 1867 

 he was appointed a Member of the Royal Commission on Metropolitan 

 Water Supply. 



He was elected a Fellow of the Royal Society in 1853, and Vice- 

 President in 1870; in that year also he became President of the 

 Geological Society. In his second address to that Society in 1872, 

 he gave an excellent and oft-quoted account of the growth of London 

 as dependent on the means of obtaining a supply of water. In the 

 same address he referred to the many aspects of geological science, 

 and remarked that, " While treating of these abstract and philo- 



1 " Geology," vol. ii., p. 364. '■^ Address to Gaol. Soc, 1854. 



