112 



THE YOUNG NATURALIST. 



of the chalk varies from 600 feet on the west of the county near Waterham, 

 to 900 feet as shown in the cliffs on the coast. 



In the splendid sections afforded on the coast, the following sub-divisions 

 may be recognised, commencing on the north in the Isle of Thanet and walk- 

 ing southwards — 



Chalk, with few Flints (Margate) ... 80 feet. 

 „ „ many Flints (Broadstairs to Dover) - 350 „ 

 „ „ few „ (Dover) - - - 130 „ 

 „ without flints - - - - 270 „ 



Marl 70 „ 



Among the chief fossils of the Chalk are : 

 Dover. 



Magas pumilla, Kingena lima, Wiynchonella plicatiles, Ostrea frons, 

 Pec ten fissicosta, Lima par allela, Crania Ignaberginsis, Oyphosoma radiatum, 

 Echinothuria floris, Salenia granulosa, Eckinoconus castcenea, Goniaster 

 coombii, Ventriculites mammillaris, V. decurrens, Ammonites navicularis, 

 jftautilus elegans, Beryx ornatus, Corax heteradon, Odontaspis gracilis. 

 Gravesend. 



Ananchytus planus, Cidaris subvesiculosa, C. clavigera, C. hirudo, C. seep- 

 terfera, Cyphosoma corallare, C. granulosum, C. Konigii, C. radiatum, 

 Eckinoconus castmnea, E. conicus, Goniaster uncatus, Ptychodus poly gyrus* 

 Northfleet. 



Magas pirmilla, Cidaris sceptrifera, C. clavigera, Parasmilia centralis. 

 Maidstone. 



Cidaris sceptrifera, Discoidea cylindris, Enoplachytia sussexiensis, Ptycho* 

 dus mammalians, P. gibberulus. 

 Bromley, 



Cidaris perornata, C. sceptrifera, C. clavigera, C. subvesiculosa, Cypho- 

 soma Konigii, Echinothuria floris, Goniaster angustatus, G. Hunteri, G. 

 Mantelli, G. Parkinsoni, G. Sultanatus, Eolostoma contingens, Micraster 

 cor-anguinum, Salenia granulosa, Parasmilia centralis {Corax heteradon). 

 Woolwich. 



Anachytes ovata, Beryx Lewesiensis, Cidaris sceptrifera, C. clavigera, C. 

 subvesiculosa, Dercetes elongatus, Galerites albo-galerus, Goniaster coombii, 

 Micraster coranquinum, Parasmilia centralis, Pecten nitidus, Spondylus 

 spinosa, Terebratula carnea, Terebratula semiglobosa. 



THE TERTIARY PERIOD. — The Chalk ends a series of deposits 

 classed as Secondary or Mesozoic (middle life) and the Strata we have now 

 to describe belong to an entirely different and later time, known as the Ter- 

 tiary or Cainozoic (recent life) period : they constitute a tract of land from 



