LOWER CHALK—CHEMICAL COMPOSITION. 
343 
Loss on ignition (organic matter) 
Calcium carbonate. 
„ phosphate. 
„ sulphate. 
Magnesium carbonate 
Lime. 
Oxide of iron and alumina 
Oxide of manganese 
Clay. 
uartz . 
olloid silica . 
Alkalis and loss on analysis 
A. 
B. 
c. 
2*14 
*60 
1*30 
71*86 
90*90 
89*38 
*82 
*31 
*31 
1*30 
*10 
*20 
2*68 
1*53 
1*28 
2*41 
2-22 
2*31 
1*45 
*47 
*59 
2*07 
*53 
*20 
6*00 
*65 
1*03 
3*49 
*43 
*96 
5*57 
1*53 
1*90 
*21 
*73 
*54 
100*00 
100*00 
100*00 
It is noticeable that the lower marl is highly calcareous, 
containing no less than 74'54 per cent, ol carbonates ; while 
the white chalk is, as one would expect, a pure limestone, con¬ 
taining over 90 per cent, of carbonate, with very small amounts 
of clay and quartz. 
