538 W. A. Richardson — The Origin of Cretaceous Flint. 

 7 2 ~3 ? & <5 ? ~e 9 



5/fl Percentage | I | 



Cldrsupitej 



<c ^'^'L2f 



/7//?/ asj'iercer 



^9<qj 



N 



/V cordinguipa/n 





/ 



9 



-**- 



/# f^?r- /?»j tudind num 



/ 



Chalk Rock 



H. folanus 



/ 



r&r<jci/i5. 



ft Cuvieri 



Melbourne, f?h 



H. subglobosus . 



15. v&ra*}rys> 



Fig. 1. — Comparison between the silica distributed in soluble form through the 

 Chalk and that present as flint. 



