2Sd ON THE FORMATION OF ROCKS. [July: 



resembling those formed every day by the action of tha 

 Sea, rivers and lakes. 



Substances, whose structure and component parts 

 are similar to those formed by the depositions of lakes, 

 sjirings &c. which are evident to our senses and daily 

 observations. 



Substances, alternating and intimately mixed with 

 all, or any, of the above description, provided, nothing 

 similar has yet been found in those, which are of un- 

 doubted volcanic origin. 



FIRST CLASS. 



Order ii. 



Of the J\*eptiinian origin. 



12. Coal formation. The series of aggregates 

 which constitute this formation, are evidently of aque- 

 ous origin: the Puddingstone and Sandstone, are com- 

 posed of particles rounded by attrition; and as well as 

 the Slaty Clay, Bituminous Slate &c. contain the im- 

 pressions of vegetable and other organic matter, wliicli 

 are, as well as the coal itself, destructible by fire, ren- 

 dering the analogy conclusive. 



They are generally found in hollows or low situa- 

 tions, when compared with the surrounding strata, 

 which may be called basins or depots, and may be 

 divided into three different basins or depots, accord- 

 ing to the different nature of the rocks, which form the 

 fiasins or foundation on which the formation lies. 



The first is the deposit in calcareous basins, or re- 

 posing on the foot of the compact calcareous mountains; 

 «uch as the coals at New- Castle and Whitehaven, in 



