4 BRITISH CRETACEOUS BRACHIOPODA. 



The following Table illustrates the principal characters of the Cretaceous System in 

 England, as well as a few of the foreign synonymic appellations. 



Upper Chalk. 



s 



CO 



02 



es 

 o 



a 

 o 



5 



w 

 3- 



P 



o 



w 

 o 

 < 



w 



a! 



o 



Lower Chalk, 



and 

 Chalk Marl. 



Chloritic Marl, 



and Upper 



Green Sand. 



Lower 

 Green Sand. 



Red Chalk, 



Speeton Clay, 



Gault. 



Nearly pnre carbonate of lime, and" 

 minute fragments of shells and 

 foraminifera, forming a white or 

 yellowish-white, or light grey soft 

 chalk, with horizontal layers of 

 flinty nodules. 



Harder chalk than the former, almost 

 without flinty nodules, under which 

 a greyish marking chalk and sand, 

 at times indurated. 



Variable in its composition, a chlo-" 

 ritic marl, containing most of the 

 species of the Upper Green Sand, 

 composed of a chalk with green par- 

 ticles, and minute grains of quartz. 



The Upper Green Sand is made up 

 of a siliceous sand, or a marly 

 calcareous sand, with green grains 

 often consolidated into nodules of 

 chert, and masses of limestone. 



A thin bed of red chalk, coloured by^ 1 

 oxide of iron, with minute siliceous 

 grains. 



The Speeton Clay is also of a grey 

 colour, containing a mixture of 

 Upper Green Sand and Gault 

 species. 



Dark blue tenacious clay, at times 

 marly, with some concretions. 



Chiefly arenaceous deposits, sand with 

 or without green grains, ferrugi- 

 / nous sandstones, beds of clayey 

 sand, clay, and bands of limestone 

 known under the name of Kentish 

 rags. 



Lewisham, Grays, 

 Northfleet, Norwich, 

 Brighton, Dover, &c. 



Near Dover and 

 Folkstone, Hinton, 

 near Cambridge, 

 near Swaffham, 

 Lewes (Sussex), 

 near Norwich, &c. 



Chard, 



Chardstock, &c. 

 near Warminster, 

 Alton, Petersfield, 



Cambridge, &c. 



Corresponds to the 

 Craie blanche of the 

 French, the Obere- 

 kreide of the Ger- 

 mans, Etage senonien 

 of M. D'Orbigny. 



"This is the Untere 

 Jcreide and Planer of 

 the Germans, the 

 Craie tufean of the 

 French, Etage turo- 

 nien of M. D'Or- 



- bigny. 



This division seems to 

 correspond to the 

 Glauconie crayeuse 

 of the French, the 

 Tourtia of the Bel- 

 gians, iheGreen Sand 

 of the Germans, 

 Etage CSnomanien of 

 M. D'Orbigny. 



Hunstanton Cliff, , ^ q{ fl- 



Norfolk, French> Gdt of the 



Speeton Cliffs, ^ 



Yorkshire, Folkstone, 



Cambridge, 

 Rigmer, &c. 



Folkstone, Hythe, 

 \ Maidstone, Shanklin, 

 and Atherfield, 

 Isle of Wight. 



Germans, Etage Al- 

 bien of M. D'Or- 

 bigny. 



This is said to repre- 

 sent the upper por- 

 tion of the Terrain 

 neocomien, or Etage 

 Aptien of M. D'Or- 

 bigny. 



