248 ON THE GEOLOGY AND MINING OF 



different deposits ; and these remains had received the appropriate 

 designation of " medals of creation." 



Similar was the process in a confined area like that under consi- 

 deration. It must be conceived of as covered by the waters of a 

 deep ocean, extending indefinitely on every side, and of which the 

 floor of limestone and other inferior strata, was gradually covered 

 with deposits of various rocky materials, carried down from distant 

 and previous elevations. The accumulated strata, with the solid 

 limestone on which they rested, were themselves elevated at certain 

 points, till high ridges rose above the waters. The debris from these 

 hills was, by continued aquatic operation, carried into the concavity 

 or trough ; and the hills themselves became, in due course, clothed 

 with luxuriant vegetation, vast accumulations of the matter of 

 which, in different stages of decomposition, were perpetually washed 

 down, and took their place as definite deposits, which, buried under 

 successive earthy layers, and subjected to the chemical and mechani- 

 cal action of heat and pressure, took the form of that which we now 

 call coal. Among other beds deposited in this trough or basin were 

 also clayey sediments, charged with metallic particles, which, in 

 process of time, took their present form of strata of iron ore, or, as 

 it is commonly called, ironstone, which occur at different depths in 

 the coal formation. The vegetable origin of coal was abundantly 

 proved by the prevalence of carbonaceous matter in its depositions, 

 and by the numerous remains which pervade every part of its mass ; 

 and the existing high temperature of the earth's crust was also in- 

 ferable from the nature of the plants discovered, which were at once 

 pronounced, by the botanist, to bear a distinct relation to those now 

 known to belong to tropical climates. Thus, the once deep sea or 

 lake was gradually filled up with sedimentary washings from high 

 lands. But it was not in this evenly disposed form that the suc- 

 cessive layers offered themselves to the miner. A series of move- 

 ments, similar to those of the earthquake and the volcano, broke up 

 the accumulated strata to an unknown depth ; placed contiguous 

 portions of the same deposits at the most discordant levels, and ex- 

 hibiting the ocean beds of thick limestone, in highly inclined posi- 

 tions, as the principal constituents of abrupt and lofty eminences. 

 That these movements took place after the deposition of all the cha- 

 racteristic strata had taken place, was clear, from the circumstance 

 of the same measures being successively reached, in the same order, 

 in places where they lay at extremely different distances from the 

 surface. 



The lecturer illustrated his subject by reference to several effec- 



