332 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



whether the clay iron-stone forms there a constituent of 

 Formation No. 4. 



Mr. Meek informs me that clay iron-stone concretions 

 occur at many places in the fourth division of the Creta- 

 ceous rock in Nebraska, but he has no knowledge of its 

 occurrence there in quantities sufficient to be considered 

 of much value. 



The Quartzose sand, highly ferruginous throughout 

 New Jersey, is one of the representatives of Formations 

 4 and 5 of the Nebraska Section, probably of No. 4. 



The richness of the clay iron-stones of the Little Souris 

 may be inferred from the following comparison: — 



The principal ore from which iron is smelted in 

 England and Scotland is the carbonate of iron of the 

 coal measures. It occurs chiefly in the form of nodular 

 masses associated with the strata of coal. This ore yields 

 from 30 to 40 per cent, iron of good quality. 



The iron-ore of the Little Souris varies in quality, 

 many nodular masses appearing to consist nearly alto- 

 gether of carbonate of iron, and possess a semi-crystalline 

 arrangement like the sparry iron of the unfossiliferous 

 rocks. An approximate analysis of several specimens 

 gave 75 to 85 per cent, of proto-carbonate of iron, which 

 would answer to 34 per cent, and 41 per cent, of pure 

 iron respectively. 



I am indebted to Professor Croft for an exact analysis 

 of a fragment of a nodule which he took, without making 

 any particular selection, from my specimens. 



He found 82*720 per cent, of proto-carbonate of iron, 

 which is equal to 39*930 per cent, of iron, or very nearly 

 40 per cent. 



The richest specimen selected by Dr. Colquhoun, from 

 the sparry iron-ores of the Glasgow coal-field, gave 

 41*25 per cent, of pure iron. This diners by 1*320 per 



