A HISTORY OF SUSSEX 



overspread the clays, or the bare heaths which characterized the sands. 

 The areas occupied by Chalk were probably in prehistoric times, and 

 even much later, the most settled and highly civilized parts of Britain ; 

 they are certainly the areas over which are found our finest and most 

 extensive prehistoric antiquities. We in Sussex scarcely realize how 

 peculiar and abnormal a deposit is this soft pure white limestone known 

 as Chalk. It occupies a small part of western Europe, but in other 

 regions of the world there is nothing very closely resembling it, except 

 in comparatively thin beds. This thousand feet of strata is composed 

 almost entirely of marine organisms — either recognizable or decayed — 

 except in the lower part, in which there is a considerable admixture of 

 clay and other detritus washed from the land. The rest of the formation 

 is so uniform that the differences are not such as to strike the casual 

 observer, who would describe the whole mass simply as chalk. On 

 examining more closely we find at different levels slight differences in the 

 character of the deposits and in their included fossils. These variations 

 extend throughout the county, so that it is usually possible from an 

 isolated chalk pit to tell approximately how high we are above the base 

 of the deposit.^ 



The lower part of the Chalk consists essentially of greyish marl In 

 alternate hard and soft beds, which make conspicuous ledges on the fore- 

 shore and at the base of the cliff between Eastbourne and Beachy Head. 

 These deposits form the Lower Chalk, which has a thickness of from 

 150 to 200 feet, and occupies the gently rising ground at the foot of the 

 Chalk escarpment. Its soil is more retentive than that of the rest of the 

 Chalk, and much of it was formerly woodland, though now it is mainly 

 under the plough or changing to permanent pasture. The fossils are 

 pecuHar. Towards the base we find a narrow zone of hard sandy chalk 

 with quartz grains and occasional phosphatic nodules. This zone is 

 characterized by the small sponge Staiironema carteri. Then follow marls, 

 breaking up into pieces with curved faces and containing Ammonites 

 varians, A. rotomagensis, Scapbites cequalis, and Holaster subglobosus^ as well 

 as numerous bivalves and fish. Most of the beautifully-preserved fish 

 remains found at Lewes and to be seen in every museum come from this 

 division. At the top of the Lower Chalk is a band 10 or 20 feet 

 thick of softer, darker, and more impervious marl, known as the 

 ' Belemnite Marl,' from its characteristic fossil Actinocamax {Belemnitclhi) 

 plenus. This marl holds up and throws out the water which falls on the 

 higher beds of chalk ; many of the springs are therefore given out at 

 the junction of the Lower with the Middle Chalk. Very little water is 

 obtained from the Lower Chalk itself, except where it is much shattered, 

 as near Eastbourne. This division of the Chalk, besides forming land of 

 different agricultural character, produces hydraulic lime, which cannot be 

 made from the beds above. 



There is a sudden change from the soft Belemnite Marl to the hard 



* The best account of the zones will be found In Dr. A. \V. Rowc, 'The Zones of the White 

 Chalk of the English'Coast : I. — Kent .ind Sussex,' Proc. Geo/. Auor. vol. xvi. pt. 6 (1900). 



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