104 GEOLOGICAL NOTES ON COAL AND IRON ORE 



formation not only of some of the coal-seams, as also of 

 certain iron-ores. In the first case it is the marine trans- 

 gressions, which are represented by the marine sediments, 

 which have preserved the accumulated masses of cellulose 

 which have afterwards been transformed to coal; in the latter 

 case the marine sediments have partly furnished material 

 for iron-ore formation, partly served as accumulators for the 

 iron which has been leached out from the other sediments. 



