STRATA. OF THE HAMPSHIRE BASIN. 139 



II. HiSTOEY OF Previous Opinion. 



The foundation of our knowledge of the succession of the Tertiary- 

 strata in Western Europe was laid by the publication, in the year 

 1808, of Cuvier and Brongniart's ' Essai sur la Geographic Mineralo- 

 gique des Environs de Paris.' It was through the study of this 

 work that Webster, who had already collected much valuable topo- 

 graphical information concerning the beds exposed on the coasts of 

 the Isle of Wight, Hampshire, and Dorsetshire, was enabled to 

 classify those fluvio-marine beds, with which we are now particularly 

 concerned, and to point out their equivalents among the strata of 

 the Paris basin. It would appear that Webster found in the Mu- 

 seum of this Society a collection of fossils procured from the neigh- 

 bourhood of Paris by Count de Bournon ; and on a comparison of 

 these with the series of organic remains which he had himself ob- 

 tained from the several divisions of the Isle -of- Wight strata, he was 

 greatly impressed with their general resemblance. So interested 

 was he, indeed, by this discovery, that, without waiting for the 

 advent of more favourable weather, he set out in midwinter to re- 

 examine the Isle-of-Wight sections, with the aid of the new clue 

 which he had obtained. The result of this investigation he gave to 

 the world in his twelfth and concluding letter addressed to Sir Henry 

 Englefield on February 11th, 1813*. 



Cuvier and Brongniart had divided the Tertiary strata of the Paris 

 basin into five groups ; and it was with the upper three of these that 

 Webster correlated the fluvio-marine beds of the Hampshire basin. 

 Hence arose the division of the Isle-of-Wight fluvio-marine beds 

 into a "Lower Freshwater Formation :" a " Middle Marine Forma- 

 tion," and an " Upper Freshwater Formation :" and this classifica- 

 tion long held its ground ; for it seemed to find support in the fact 

 that at many points marine strata might be observed with fresh- 

 water beds lying both above and below them. 



But subsequent observations, especially those of M. Constant Pre- 

 vost, demonstrated that the simple classification of Cuvier and Brong- 

 niart did not hold good, even for all parts of the Paris basin ; while 

 Mr, Prestwich's researches in this country proved that Webster and 

 those who followed his views, in seeking to bring into exact agree- 

 ment the succession of beds in the Paris and Hampshire basins re- 

 spectively, had confounded together deposits as distinct from one 

 another as the London, Bracklesham, and Barton Clays. 



With respect to the fluvio-marine beds, however, Webster's three- 

 fold division long held its ground, and was unhesitatingly accepted 

 by all geologists. The researches of Sedgwick, Lyell, Bowerbank, 

 Mantell, and others added many new facts to the stock of informa- 

 mation acquired concerning these beds ; while the important dis- 

 covery that they contain a mammalian fauna similar to that of the 

 gypsum of Montmartre (which discovery was made by Dr. Buckland 



* ' A Description of the Principal Picturesque Beauties, Antiquities, and Geo- 

 logical Phenomena of the Isle of Wight,' by Sir Henry Englefield, Bart. (London, 

 1816), p. 226. 



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