502 The Mineralogiecd Resources of Ireland. [Oct., 



becoming gradually more earthy, and being split into separate 

 layers by the intercalation of shales and sandstones. Throughout 

 the whole series, amounting vertically to several thousands of feet of 

 strata, there is no abrupt change, or break, in the succession of the 

 beds of any importance; a fact which should be borne in mind, 

 because on it depends much of the strength of our reasoning from 

 analogy when we come to the case of Ireland. 



Now, reverting to this country, what do we find ? "We find the 

 very same succession of strata, from the base upwards, through a 

 certain distance in the vertical scale, but no farther. We may 

 observe the Carboniferous limestone — the basement layer of the 

 coal-bearing superstructure in Britain — spread over an enormous 

 tract of country, and forming nearly the whole of the central plain 

 of Ireland ; and resting on this, at intervals, we have small tracts of 

 strata, with a few thin seams of coal, representing the Millstone 

 grit and Yoredale series of England and Wales ; but here the suc- 

 cession ends. We look in vain for the deposits of coal-bearing strata 

 — or true Coal-measures — which in Britain are the repositories of 

 the most important beds of mineral fiiel. 



To account for this want — this truncation, in fact, of the most 

 economically important portion of the great Carboniferous formation 

 in Ireland — the geologist has a theory which is inteUigible and con- 

 sistent with experience as obtained in some parts of Britain itself. 

 Our readers are probably famihar with the tracts of hilly ground 

 in parts of Yorkshire and Derbyshire, called " the Penine Chain," 

 which separate like a " backbone " the coal-fields of Lancashire and 

 Cheshire on the one hand from those of Derbyshire and Yorkshire 

 on the other. These hills are composed of Carboniferous hmestone 

 and Millstone grit, the basement series of the Coal-measures ; and 

 no one familiar with the similarity of the strata on either side of 

 this dividing ridge can doubt for a moment that the strata of which 

 the ridge is formed were originally overspread by deposits of coal- 

 bearing strata. Equally certain is it, that a large portion of the 

 Carboniferous limestone of the central plain of Ireland was once 

 overlaid by coal deposits ; but they are gone, as are those of the 

 Penine Chain in Derbyshire; and in both cases they have dis- 

 appeared through the agency of " denudation," a term by which we 

 express the removal of masses of strata, by the agency of rivers, 

 seas, and other forms of water at distant periods of the earth's 

 history. 



Denudation, then, has despoiled Ireland of her mineral resources, 

 and for all time has moulded the character of her inhabitants. Who 

 can say, how diff'erent might have been her history had an abundance 

 of mineral wealth stimulated the natural genius of her sons, and 

 rendered her the centre of mining and manufacturing industries ! 



From these speculations let us now turn to the consideration of 



