CORRELATION OF THE BOURNEMOUTH BEDS. 227. 
The extraordinarily shifting and rapidly changing character of 
the beds both horizontally and vertically, the marshy character ot 
the vegetation, as represented by ferns, Hucalyptus, Aroids, &c., 
the frequent patches of drab clay (which evidently once formed an 
oozy soil in which the ferns and perhaps water-plants rooted), the locai 
patches of ironstone, the marine beds, as well as the character of 
the fauna, shore-crabs and Callianassa, mingled with Unios, clearly 
show that this was the actual debatable margin betwixt sea and 
river, beyond which, to the west, it seems clear the encroaching 
sea never 1n these ages penetrated. 
With regard to the correlation of the Bournemouth Marine beds with 
those of the London Basin, itis clear, upon reading Prof. Prestwich’s 
description of the Middle Bagshot series in that area, that the beds 
are lithologically very similar. He ascribes to it a thickness of 
from 40 to 60 feet, and considers it to be a division of distinct 
mineral character and persistent range and structure. Whitaker, 
in the Geological Survey Memoir*, adopts Prestwich’s divisions, and 
quotes largely from his work. The lower part consists of laminated 
clays and sands; above these there is “ green sand, generally very 
pure and of a dark bottle-green colour,” 12 to 20 feet thick, suc- 
ceeded by other sands and clays, with occasional layers of rolled flint 
pebbles. ‘The presence of glauconite grains is a distinctive feature 
of the Middle Bagshot division, and the fossils that have been found 
are Bracklesham species. There can, I think, be no reasonable doubt 
that these beds represent the same stage of the Bracklesham series 
in the London Basin. When we come, however, to the Upper 
Bagshot beds in the same area, considerable doubt exists. These 
sands are described in the Survey memoir as ‘loose, generally 
whitish, and without signs of bedding or pipeclay, and are 250 to 
300 feet thick.” Considering that the Bournemouth marine beds 
are overlain by heavy deposits of white sand in every respect 
answering to this description, and that the Hengistbury-Head beds 
are also under a thick mass of whitish sand, and in the absence 
of paleontological evidence, it seems far more likely that these 
belong to Middle than Upper Bagshot time. On this supposition 
we have neither the very sudden thinning of the Middle Bagshot 
nor the absence of any indication of the Barton Clay to account for. 
I am therefore of opinion that no Eocene beds younger than the 
Brackleshams are met with in the London Basin. ‘There is one 
other point upon which I wish to remark. The fossil plant-remains 
met with in the Bournemouth beds, especially those in the marine 
series, are so strikingly similar to the Bovey-Tracey fossils as to 
make it clear to my mind that the latter have been wrongly assigned 
to the Miocene. I believe, in fact, that they are simply an outlier 
of the Bournemouth series, from which they are but eighty miles 
distant. Whether we compare the ferns, as Osmunda (Pecopteris) 
lignita, Lastrea Bunburyi, the Cactus* (Palmacites demonorops), 
the fruits, conifers, or dicotyledons, it is seen that by far the 
larger proportion are not only specifically identical, but occur 
* Mem Geol. Surv. vol. iv. p. 329. 
