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analogy or relation to it as the larger masses do, and similar to the 

 veins usually observed in slate-works when resting on granite. 

 These branches appear as if they had been squeezed or forced 

 up from the trap bed by the pressure of the superincumbent 

 beds upon it, similar to what would take place in a bed of soft 

 clay confined, if covered by a layer of stones ; the clay would 

 be forced up between the joints, and such are what are called 

 centres of eruption in the above coal district. Where the coal 

 happens to be in contact with the above rock, it is more or less 

 impregnated with substances corresponding to it, and always 

 saturated with mineral waters, which coal, when dry, presents a 

 somewhat reddish and greyish appearance, vulgarly called i burnt 

 coal -' but absolute fusion had no more to do with this change 

 in the character of the coal in contact than it has to do with any 

 other slow chemical saturation by the humid way. 



" The following quotation from a recent work on this subject 

 will give some idea how the volcanic action is pushed beyond its 

 natural limits to explain phenomena with which it either has 

 none, or, at best, very little connexion ; and it will also exhibit 

 the kind of reasoning, called i a strict process of induction/ by 

 which the igneous theory is established :-— ( The modes in which 

 trap rocks, and, in fact, all the primary rocks occur, strongly 

 countenance the idea of injection from below; and their occa- 

 sional striking resemblance to the products of existing volcanoes 

 shows that the agency by which they were produced was that 

 of subterraneous heat, and therefore closely resembling, if not 

 identical with, volcanic action. One or two decisive facts in 

 support of these views may not be misplaced. When dykes or 

 masses of basalt or trap come in contact with beds of coal, the 

 coal in its vicinity is generally found to be converted into coke 

 or cinder, clearly proving, that when the basalt assumed its pre- 

 sent position, it must have been in an intensely heated state ; 

 and as it now occurs, completely filling the cracks, &C, in the 

 coal strata, there can be no doubt that when ejected from below 

 it was in a state of actual fusion. Were further proof needed 

 that such is the origin of basalt or trap rocks, it would be fur- 

 nished by the fact, that this rock often resembles lavas, not 

 merely in its external texture, but in actual composition. We 

 have thus clearly established the igneous origin of this class of 



