1872.] MEYEE — WEALDEN AKD '' PTTKriELD FORMATION." '247 



thickness of these Wealden strata a continual, although oft-repeated, 

 variation in the character of the deposits ; yet one might venture to 

 say, even on stratigraphical evidence alone, that nine tenths of the 

 Avhole was quietly accumulated. The fine-grained sandstone and 

 quartzose grits of the lower beds, the stiff red clays of the middle, 

 and thinly foliated "marl with Cypris''' of the upper Wealden might 

 all be of lacustrine origin, and yet include both tree-stems and the 

 bones of reptiles. There is, indeed, in these, again, as in some por- 

 tions of the Purbeclc strata, a strong resemblance to the Tertiary 

 lacustrine beds of Central Prance. 



The mollusean remains of the true freshwater Wealden strata are 

 too well known to need remark. The mode of their occurrence, dif- 

 fering here and there according to the condition of the strata in 

 which they are imbedded, appears to agree very well with the idea 

 of a combined fluvio -lacustrine origin. Judged by these fossils and 

 the mode of their occurrence, the waters of the lower and middle 

 Wealden must have been extremely shallow and much disturbed at 

 times by river-action. The finely laminated strata of the Upper 

 Wealden (and I include in this the so-called " Punfield-beds " of 

 Atherfield and Compton Bay) are such as, on the contrary, belong to 

 deeper waters, and rarely, if ever, show traces of disturbance. If, 

 then, the Wealden beds, like those of the Purbeek, originated in an 

 area not open to the sea, the varying condition of the strata must in 

 some way be accounted for. 



Now the evidences of river-action as seen throughout the "Wealden 

 area point to two facts, which are, indeed, very generally admitted — ■ 

 namely, first to the elevation, secondly to the slow depression of 

 the surrounding country during the Wealden epoch. Its elevation 

 was probably the greatest during the accumulation of the lower and 

 middle Wealden strata, at which time the force and carrying power 

 of the Wealden rivers, as looked at from my point of view, was in 

 excess. Its depression from this time onwards was probably con- 

 tinuous, diminishing the river-action, adding depth to the Wealden 

 waters, and placing eventually the Wealden lacustrine area below 

 the sea-level. 



Now it is a well-known fact that the higher beds of the Wealden 

 are not only extremely uniform in character, proving to some extent 

 their deep-water origin, but also contain freshwater fossils up 

 to their very junction with the Neocomian strata. It is a fact also 

 that the change from Wealden to Neocomian was an abrupt change ; 

 the passage bed, as may be seen at Atherfield and Redcliffe, in the 

 Isle of Wight, and as I have seen it also at Haslemere * and Seven- 

 oaks, is but a few inches in thickness, and consists of the same slaty 

 clay as the underlying Wealden strata of which it forms a part. It 

 contains, however, a curious assemblage of freshwater and brackish- 

 water fossils, some of which are found in no other stratum of the 

 Wealden with which we are at present acquainted. The most 

 noticeable of these is a shell mentioned by Fitton in 1843 as pro- 



* See also a note by Mr. Salter, Mem. Geol. Survey, Isle of Wight (1862), 

 p. 18. 



