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" There are lew finer sections of the coal deposits anywhere in 

 Britain than those laid open along the shores of Granton, Mussel- 

 burgh, and Prestoupans ; and the section of the mountain lime- 

 stone exposed in the ravine at Dry den, is, as far as I have yet 

 seen, the most extensive in Scotland. By those who hold, as is 

 done by some of the geologists of our Western capital, that this 

 formation is wanting as a base to the Scottish coal field, a visit to 

 this section might be found very instructive. It does not exhibit 

 that great thickness of limestone for which the corresponding 

 formation in England is so remarkable, but presents for several 

 hundred feet together, in its encrinal bands, intercalated amid shales 

 and sandstone, evidence of a marine origin ; and its upper calcar- 

 eous beds, laden with spirifers and producta, and of very considerable 

 thickness, show that a tolerably profound sea must have covered the 

 field shortly ere the formation of our older beds of workable coal." 



These remarks, however, hardly impugn the statements already 

 put forward ; this limestone is not at the base ; its thickness is 

 not great ; and its encrinal bands are intercalated among shales and 

 sandstones, which contain the same fossils. The sea was indeed 

 deep ; but it was not a sea of coral reefs, nor of pure chemical de- 

 posits; its waters, by means of frequent floods, were widely dis- 

 coloured by vast irruptions of black mud, and red or white sand, 

 with which calcareous matter was sparingly mixed ; and thus the 

 whole deposit is of one age, while the limestone is truly, from its 

 fossils and mineral character, the same as the mountain limestone, 

 though not en masse in the same position. The shales and sand- 

 stones, with its separated portions intercalated among them, represent 

 in all particulars the great English formation, underlying tJie coal. 

 What a long series of changes and vast lapse of time are implied 

 in the elaboration of these strata in the bosom of the primaeval 

 ocean ! Its deep bed was often laid dry, and on the desiccated sur- 

 face lakes were formed, which became the abode of cyprides and 

 other fresh-water genera. These conditions so long prevailed, and 

 the individuals continued to exist in such countless myriads, that 

 thick and widely continuous beds of limestone were accumulated 

 from their exuviae. Again the area subsided to a small depth, 

 the sea found an entrance, and a thick coal seam and shale beds 

 with marine remains were deposited. A continued subsidence to an 

 enormous amount succeeded, and a vast series of shales and sand- 

 stones, and a few seams of coal and beds of limestone, charged 

 throughout with a prodigious variety of marine fossils, were slowly 

 accumulated. Again, by some mighty internal convulsion, a new 



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