48 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jlllie 14, 



beginning to end ; clays replacing sands and sands clays, horizontal 

 lamination giving way to oblique lamination, and then changing again, 

 with extreme frequency. So great are the changes, that if the 

 country were only exposed, here and there along the line of cliff, by 

 pits, it would hardly be supposed that the sections were in one and 

 the same stratum. 



Westward of Bournemouth the division into layers of coarser sand 

 and fine clays is more marked ; pipeclays become more frequent. It 

 was in one of the latter subordinate layers, a short distance w^est of 

 Bournemouth, that the Rev. P. B. Brodie discovered the impressions 

 of leaves ''' : they are beautifully preserved, and in one or two seams 

 are most abundant, but the species are not numerous. At the end 

 of the cliff, towards Poole Harbour, there are indications of the 

 appearance of an underlying bed, consisting of a dark grey clay with 

 numerous flat masses of iron pyrites ; without seeing it, however, in 

 greater extension, it would be difficult to say whether it is or is not 

 subordinate to the sands of Bournemouth Cliff. 



As a whole, this stratum may be considered to consist of whitish 

 and yellow sands, occasionally very coarse, irregularly laminated with 

 subordinate dark carbonaceous clays, which latter are however chiefly 

 developed in the middle part of the stratum. It represents pro- 

 bably the strata Nos. 27 and 28 of the Section of Alum Bay Cliff, 

 and consequently the fossil plants of Bournemouth occupy a higher 

 position in the series by 300 to 400 feet than those of Alum Bay, 

 which occur in stratum l/f- Compared with the strata around Lon- 

 don, these beds would form part of the Upper Bagshot sands, or 

 the upper part of the Bracklesham Bay series of Hampshire. 

 The clays worked within a mile or two of Poole I believe also to 

 belong to the same series, but I am not yet in possession of data 

 sufficient to establish a continuance of the series downwards. The 

 sections are numerous ; but they are not connected, and the want of 

 fossils, and the rapid changes which we know to take place in the 

 same stratum on the same level, and of which I have further seen 

 some interesting examples in the railway-cuttings between Poole and 

 Wimbourne, together with the frequent repetition of very similar 

 characters in the different vertical parts of this series, render it 

 necessary to proceed in the study of the relative superposition of the 

 strata in this part of the country with much caution. 



As a study of a peculiar physical tertiary structure, this is a 

 district of considerable interest. In the east of the Isle of Wight 

 we observe the portion of the eocene series between the London clay 

 and the Barton clay to consist of clays and fine sands repeated with 

 but little variety and in considerable thickness. The absence of 

 strong drifts is denoted by the abundant fossils and by the beds of 

 shells in their normal position, uninjured as at the moment of their 

 entombment, whilst vegetable remains are scarce. At Alum Bay, on 

 the contrary, the remains of drifted vegetables are common ; the strata 

 are strongly marked, — fresher, as it were, from their source ; exhibit 



* Proc. Geol. Soc. vol. iii. p, 592. 



t Journ. Geol. Soc. vol. iii. section p. 408. 



