11 



OCCURENCE OF NATURAL PHOSPHATES IN THE GEOLOGICAL EPOCHS. 



Fost-tertiary or Quartertiary System. 



True guanos. 



Crust or "leached" guanos. 



West Indian and Pacific Phosphates. 



Tertiary System. 



West Indian Rock Phosphates. 

 Nassau or I-ahn nodular concretions. 



Suffolk Coprolites in the Red Crag and Coralline Crag. (Repos- 

 ing on the Lower Eocene ) 



S. Carolina beds, resting upon Eocene. 



Deposition of Florida phosphate debris and organic remains. 



N. Carolina overlying Eocene marl. 



Fundamental rock of Florida Phosphate deposits. 



Clays and debris of Bordeaux Phosphates. 



Cretaceous System. 



Belgian (T>iege) Hesbaye nodules. 

 American Alabama amorphous nodules. 

 New Jersey marls 



Belgian (Mons) Ciply nodules (Maestricht beds). 

 Somme deposits, arenaceous and nodules. 

 Russian "Samorod" nodules Desna-Don. 

 Cambridgeshire and Bedfordshire Coprolites. 

 French nodules of Ardennes, Meuse. 



" " Montpellier and Bellegrade. 



Oolitic or furassic System. 



Bordeaux Phosphorites and nodules overlain by Tertiary (Eocene) 

 clays and debris. 



Algerian Phosphates. 



Trias sic System. 



Highly phosphatic beds (between Trias and below Lias) con- 

 taining exuviae of huge reptiles as well as remains of fish and crusta- 

 ceans. 



Permian System. 



(Appearance of reptilia.) 



Carboniferous System. 



(Appearance of Amphibia.) 



Devonian or Old Red Sandstone. 



Hignly phosphatic beds in conjunction with Lower Carboniferous. 

 Highly phosphatised beds in Shropshire, containing oldest known 

 remains of vertebrate life associated with crustaceans. 



