156 Cycles of Sedvmentation in the Eocene. 
In Bracklesham Bay the Lutetian and Ledian Series are not 
separated by any continental deposits, but there is a faunal break.1 
In Whitecliff Bay the marine Lutetian passes up Into a succession of 
laminated sandy clays with lignitic seams in the upper part 
(Fisher's Bed VIII). The presence of underclays with rootlets in 
this division shows that there really was a recession of the sea 
towards the close of Lutetian, and that the vegetable matter was not 
simply drifted into these beds by marine currents. It was probably 
a swamp near sea-level. Near Bournemouth the break between the 
Lutetian and Ledian is marked by the Boscombe Sands, with their 
thick beds of coarse shingle. Some difference of opinion exists as to 
the conditions under which the Boscombe Sands were formed. 
The most obvious interpretation seems to the present writer to be 
that of subaerial shingle-banks, left by the retreating Lutetian sea. 
The extraordinary bleaching and alteration of the pebbles, as well 
as the absence of glauconite in the accompanying sands, supports 
this idea rather than that of submarine shoals. 
Ledian.—The paleontological break between the Lutetian 
(Lower Bracklesham) and the Ledian (Upper Bracklesham) is a 
well-marked one. Not only has one the two very distinct species 
of Nummulites—N. levigatus characteristic of the former and 
N. variolarius of the latter—but the whole faunas are quite distinct. 
There are many Ledian species which do not occur in the Lutetian 
but which range up into the Bartonian. As several authors have 
pointed out, there is a more marked paleontological break between 
the Lutetian and Ledian than between the Ledian and Bartonian. 
The Ledian is entirely marine in both Bracklesham and White- 
cliff Bays. In Alum Bay there are 47 feet of glauconitic clays below 
the band with Nummulites Prestwichii (a band which is usually taken 
as the base of the Barton Clay). There is a strongly marked pebble- 
bed at the base of these clays. Nwmmulites variolarius has not been 
found in Alum Bay, and the present writer is uncertain whether this 
47 feet of strata should be considered as representing the Ledian or 
whether it should be linked with the Bartonian. The Ledian seems 
to be represented in Bournemouth Bay by the Hengistbury Head 
Beds. The latter pass up into the Highcliffe Sands (of the Survey). 
The lower part of the latter show ‘‘ wash-outs” and little seams of 
pipeclay, and on the whole presents a fluviatile aspect. Although 
in the Highcliffe section obscure casts of marine fossils are said to 
have been found, these sands seem to represent a feeble development 
of continental Ledian. Certainly the continental Ledian is very 
poorly developed, and the break between the Ledian and Bartonian 
is principally paleontological. 
Bartonian.—The Bartonian cycle has already been discussed. 
Stratigraphically it seems likely that the base in the Highcliffe 
1 Boussac, ‘‘ Observations sur la faune des couches supérieures de 
Bracklesham a Nummulites variolarius’’: Ann. Soc. géol. Nord, vol. xxxvi, 
1907, p. 360. 
