Geological Society of London. 233 
sham, the Calcaire Grossier, and the Nummulitic, is to be rendered 
obsolete, their classification as Middle Hocene must be preserved, and 
a modified Upper Hocene constructed out of the Barton series. The 
authors’ proposal is that the following should be adopted :— 
London Area Hampshire Area. 
( Upper Barton. 
Upper Eocene - Middle ,, 
\ Upper Bagshot Sands. Lower ,, 
The base of the formation is not sharply defined, but it coincides 
with the final disappearance of several subtropical Mollusca, and 
almost with the extinction of Nummulites in our area. The upper 
limit is drawn at the base of the Lower Headon, where the brackish 
fauna gives place to one of fresh water. 
The conditions of deposition were examined at some length, and 
evidence in support of the estuarine origin of the formation was 
adduced. The section in Christchurch Bay was described first, and 
the thickness and characteristics of each subdivision given, the total 
reaching 170 to 180 feet. It commences with 45 feet of whitish sand, 
and, in ascending order, a pebble-bed, 11 feet of greenish clay, and 
a band of imperfect ironstone underlying the zone of Nummulites 
elegans. ‘Then 20 feet of stiff drab clay, 13 feet of drab clay with 
sand-drifts, and 12 feet of the same, known as the Highcliff Sands. 
The Lower Barton terminates with the Pholadomya-bed. ‘The fauna 
of this division comprises many Bracklesham species, which range 
no farther up, and a large number of peculiar species. ‘The most 
convenient base-line for the Middle Barton is the lowest of several 
bands of Septaria, which distinguish the 50 feet of drab clays which 
are comprised in it, and it terminates in a very remarkable formation 
known as the shell-bed, which, though only a foot or two thick at 
Highcliff, thickens to about 15 feet to the east, and to 22 feet in the 
new Christchurch cutting. The finest Barton fossils are obtained from 
the Middle division ; but though so many splendid species characterize 
it, few are absolutely confined to it. The upward range of a 
further number of Bracklesham species ceases at the shell-bed. 
The Upper Barton includes the Chama-bed, the Becton Bunny and 
the Long-Mead-End beds. 
The Becton Bunny beds, 52 feet thick, are sand in the lower half 
and sandy clay above—Oliva Branderi is the characteristic fossil, 
and a large number of bivalves and brackish Headon Gasteropods 
come in. Opinions have differed considerably as to whether these 
beds should be included in the Bartons. The series closes with the 
Long-Mead-End Sands, 20 feet thick, with similar fossils, and formerly 
known as the Upper Bagshot Sands of the Hampshire basin. The 
section is continued without any break into the Lower Headon. 
The next section described was that exposed in the cuttings for the 
new line from Brockenhurst to Christchurch, and here great changes 
in the relative thicknesses are seen, confirming the view that the 
Barton formation is the local deposit of a limited estuary. The | 
Chama-bed remains 18 feet thick, but the shell-bed thickens to 22 
feet, and the drab clay with Septaria is only 10 feet. ‘The under- 
