094 ON THE FORMATION OF ROCKS. [July, 



SO. Gyiisum resembling in structure and com- 

 ponent parts the gypsum of tlie alluvial^ alternating 

 with clay, and other rocks of the Neptunian forma- 

 tion, in which the remains of organic matter have been 

 found, must be considered as proof of its Neptunian 

 origin. 



This gypsum is generally found in the vicinity of 

 mountains, as round the foot of tlie Hartz, and con- 

 tains sulphur. It is also found near to Cracow in Po- 

 land, in Murcia, Granada, and at Conila, in Spain. 

 It has quartz and arragonite crystals imbedded in it in 

 the provinces of Arragon and Valencia, in Spain, in 

 which kingdom this formation is extensive, but much 

 broken and confused, liaving its stratification irregular 

 and deranged, so as to be difficult to ascertain the re- 

 lative situation. It is probable that the gypsum near 

 Cognac in France, and that near Chalons on the Saone, 

 are likewise of the same formation. 



ti. Sandstone with an iron ochrey cement. This 

 resembles the other sandstone formation, being com- 

 posed of particles of rocks rounded by attrition; in 

 some places forming puddingstone, the sandstone serv- 

 ing as the cement. It includes and alternates with 

 clay in a soft state, and with gypsum. The remains 

 of organic matter, though rare, have been found in it, 

 which renders the analogy conclusive, of its being of 

 Neptunian origin. 



This, like all the other sandstone formation, is lia- 

 ble to be washed away when exposed to the weather, 

 and is then found in broken and detached pieces, when 

 not protected by some more solid covering. These de- 



