MIDDLE CHALK—SUSSEX. 
399 
Above this, as at Dover, the chalk has no longer a smooth 
fracture, but has a lumpy texture, and is without any well-defined 
planes of bedding, the few flints that occur being scattered and 
not arranged in lines. Holaster planus occurs in this chalk, but 
Micrasters are rare, and we regard it as the highest part of the 
Terebratulina zone. There is quite 20 feet of this lumpy chalk at 
Beachy Head before reaching a band of still more rough and 
nodular chalk, in which Micrasters are common, and it is the latter 
that we take as the base of the Holaster planus zone, and 
consequently refer to the Upper Chalk. 
The following measurements of the beds exposed below Beachy 
Head were taken by Mr. Hill in 1897 : — 
feet. 
Upper 
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Chalk —Zone of Holaster planus 
Bough lumpy creamy-white chalk, passing down 
into firm white chalk ; a few scattered flints at 
the top _______ 
Firm white chalk in massive courses, from 12 to 
27 feet thick, divided by layers of soft marl from 
6 to 9 inches thick. Some of the beds are mottled 
with grey - -- -- -- - 
Firm white chalk in thick beds, divided by thin 
seams of marl 
Firm white chalk, with many fragments of Inocera- 
mus shell ; in courses divided by thin seams of 
marl --------- 
Bather hard white chalk, streaked with greenish 
grey, in thick beds containing much Inoceramus 
\ shell. Layers of nodules can be seen in the 
cliff --------- 
Hard rough whitish chalk, veined with greenish- 
grey, in courses separated by thin seams of marl 
(Melbourn Bock) - - - . - - seen for 
Lower beds concealed by landslip - - 
21 
93 
12 
11 
54 
10 
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214 
2. Neighbourhood of Lewes. 
The range of hills which runs from Newtimber through Ditch- 
ling Beacon to Lewes coincides with the axis of a synclinal flexure, 
parallel to which there is a corresponding anticline passing through 
Povnings, Pangdean, Palmer, Kingstone, and Beddingham. 
The structure of the hill range is illustrated by the accompany¬ 
ing section, Pig. 71, which has been drawn from a sketch and 
data furnished by Mr. C. Beid. At Lewes the range is breached 
by the valley of the Ouse, and the section is drawn through 
the “ Cliff Hills ” on the eastern side of the Ouse Valiev. It will 
be seen that the dips are considerable, about 25° on each side of 
the syncline, so that at Lewes not only the Middle Chalk but also 
some of the Upper is brought down to the level of the river. 
The following particulars respecting the exposures of the Middle 
Chalk near Lewes are compiled partly from notes supplied by 
Mr. Beid and Mr. Bhodes, and partly from the researches of 
Professor Barrois already mentioned. 
