116 DOLOMITE. 
which was found to contain 37°8% of carbonate of magnesia. 
Again, Dana brought from the coral reefs of the Pacific 
Ocean a specimen of a recent coral conglomerate containing 
38% of magnesic carbonate. There is, however, evidence 
to shew that the Dolomite of the Permian rocks of 
Derbyshire was formed directly by the interaction in inland 
lakes, under the climatic conditions that characterised that 
epoch, of concentrated river and sea waters carrying alkaline 
carbonates, calcite carbonate and magnesian salts in solution. 
An indirect consequence of the reactions that were thus 
brought about is the abundance of gypsum in some of the 
overlying beds. 
