steepness to the ease with which the clay is denuded, 

 at Burham, Aylesford, etc. 



May be studied 



Chalk. — This is lithologically divisible into (from below upward). 



(i). Chalk Marl. 



(2). Grey Chalk. Seen in pits at Wouldham, near Kit Coty House, 

 Cliffe, Upper and Lower Hailing, etc. 



(3). Lower White Chalk, without flints or with a few scattered ones 

 only. Seen in chalk quarries : Trechmann's, Whorne's Place, 

 220ft. exposed, showing Lower and Upper Chalk, with visible 

 junction ; pits near Kit Coty House ; above Boxley, etc. Water- 

 containing beds. 



(4). Upper White Chalk, with flints in tabular or nodular layers. 

 Sections seen in chalk pits at Luton, Chatham Hill, Whorne's 

 Place, Borstal, Hailing, above Boxley, etc. Water-collecting 

 and conducting beds, junctions of Upper and Lower White 

 Chalk, usually marked by lines of yellowish chalky clay, known 

 as soap by workmen. 



A more useful and scientific division of the chalk beds is into hotizons 

 or life zones, by reference to the predominating and associated 

 fossils found characterising different levels of strata. Mr. G. E. Dibley, 

 a well-known local geologist and a recognised authority upon the 

 subject, contributed a valuable paper to The Rochester Naturalist 

 (vol. III., p. 297, ei seq.), from which the following tables have been 

 compiled : — 



List of Life Zones or Horizons as represented in Kent, Sussex, 



and Dorset. 



(Arranged in ascending order.) 



Life Zone. 



Chalk Marl 



Holaster sub-globosus 



Actinocamax plena 



Rhynconella cuvieri 



Terebratula gracilis 



Holaster planus 



Micraster cor-testitudinarium 



Micraster cor-anguinum 



§5^ / Uintacrinus 



* S c I Marsupite 



Sgg I III f Actinocamax quadratns. 

 ^^ ' ^•S^ \ Belemnitella mucronata. 



Kent. 



ft. 

 50 



150 

 10 

 70 



161 

 34 

 56 



280 

 68 

 48 



Sussex. 



ft. 



100 

 170 



34 



109 



242 



28 



48 



170 



Dorset. 



100 

 170 

 48 

 109 

 242 



182 



No. of Life Zone 

 on next Table. 



12 

 II 

 10 



9 

 8 



7 

 6 



5 



4 

 3 

 2 

 I 



