1896. JOSEPH PRESTWICH. gi 



may be considered his chief work — the elucidation of the Eocene 

 strata of the London and Hampshire basins. 



Commencing in the London area he zealously traversed the 

 country wherever the Lower Tertiary strata were to be found, and 

 hardly an outlier of any importance escaped his observation. Mr. 

 Whitaker, who more than any other man has followed in the foot- 

 steps of Prestwich over this large region, referred in 1872 to the 

 literature of the subject, and remarked that the period 1841 to i860 

 " might well be called the ' Prestwichian period,' from the author 

 wiio first clearly made out the detailed structure of the London 

 basin."' 



After certain preliminary studies, the interest and difficulties of 

 the subject, as Prestwich himself relates, speedily induced him to take it 

 up with more earnestness and determination, and eventually led him to 

 extend his enquiries over an area which at first he never contemplated. 

 With true enthusiasm he remarked " The Tertiary geology of the 

 neighbourhood of London may be wanting in beauty of stratigraphical 

 exhibition and in perfect preservation of organic types, but in many 

 of the higher questions of pure geology — in clear evidence of remark- 

 able physical changes — in curious and diversified palaeontological data, 

 however defaced the inscriptions, which is after all but a secondary 

 point, few departments of geology offer, I think, greater attractions." 

 These statements were made in 1849 when De la Beche handed to 

 him the Wollaston Medal, which had been awarded by the Council 

 of the Geological Society. He had then completed but a portion of 

 those labours which established his reputation as the leading authority 

 on our Tertiary strata. Having already extended his researches from 

 the London to the Hampshire basin, he subsequently followed the 

 strata into Belgium and France, correlating the divisions he had 

 made in this country with those established abroad by Dumont and 

 D'Archiac. 



His great aim was, by studying in detail the lithological 

 characters of the strata and their fossils, to mark out the main sub- 

 divisions in the Eocene system, and to picture the ancient physical 

 conditions which attended their formation. By following the strata 

 from point to point he was enabled to record the mineral changes 

 which many of the subdivisions undergo, and to note the changes in 

 fauna that accompany these variations in sedimentary condition. He 

 also showed how differences in the flora in certain formations pointed 

 to distinct land-areas. Thus were fossils employed, as they should 

 be in geological investigations, in interpreting the physical conditions 

 of the strata after the stratigraphical features had been determined, 

 and in aiding the subsequent correlation with distant deposits. 



In his earlier papers on Eocene formations he dealt with the age 

 and relations of the London Clay and Bagshot Beds. He proved the 

 connection of the London Clay and Bognor Beds, and showed that they 



1 Mem. Geol. Survey, vol. iv., p. 395. 



H 2 



