BRITISH ASSOCIATION. 



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that they were formed under water ; but in the Lancashire 

 coal-field, no remains of fishes or shells have yet been found 

 in the coal, nor is there any indication, either by admixture 

 of sand or silt in the seams of coal, to show that they were 

 drifted into the places they now occupy by rapid currents of 

 water. The occurrence of forests of large trees standing 

 upright on the seams, the pure vegetable matter composing 

 the coal itself, with scarce any admixture of foreign ingre- 

 dients, the position of the coal upon a rich alluvial deposit 

 well adapted to sustain a luxuriant vegetable, seem to prove 

 that, in most instances, the vegetation matter forming it, 

 grew upon the spot where the coal is now found ; whilst the 

 splitting and alterations in the thickness of the seams 

 themselves, show that the surface was most probably subject 

 to frequent subsidences. 



Dr. Buckland remarked, that the observations of the late Mr. J. E. 

 Bowman, Mr. Logan and Mr. Binney, had obliged geologists to modify 

 their opinions. He now believed that the greater part of the coal- 

 measures had been formed from the Lacustrine deposits, whilst certain 

 portions were still to be considered of marine origin, and probably 

 drifted into estuaries and embouchures of rivers, and interstratified with 

 terrestrial and fluviatile remains. 



Sir H. T. De la Beche observed, that the under clay had been found 

 retaining the same characters in Glamorganshire, in the neighbourhood 

 of Bristol, in Yorkshire, in Scotland and Ireland, and Mr. Logan had 

 discovered it as constantly in the coal-fields of Pennsylvania and Nova 

 Scotia ; and he thought some common cause ought surely to be assigned 

 to phenomena so widely diffused. That the coal itself was of vegetable 

 origin there could be no doubt, and the researches of Liebig had shown 

 that such a change might be effected chemically under certain conditions , 

 With respect to the subsidences supposed to have attended the formation 

 of coal, he considered such occurrences to have been frequent up to a 

 very later period ; submarine forests composed of standing and prostrate 

 trees were common, and he described one in the bay of Swansea, where 

 the fundamental rock was covered with clay and peat, and above were 

 the trunks of trees, standing as they grew, with their roots in the peat ; 



