Wright — Pakvosoic Floor of North- East Ireland. 633 



exposure of portion of the Palteozoic floor in that direction, even though such 

 portion may no longer be exposed. In this way buried ridges may be located, 

 and some idea of their composition might in certain cases be also ohtained. 

 These last methods have been employed by Professor Kendall in his specula- 

 tions as to the structure of the Palaeozoic floor of England. 1 



'The Basaltic Plateau of Antrim and the extension of the Lowland Valley 



of Scotland into Ireland. 



The only extensive area in Ireland where the Palaeozoic rocks are concealed 

 by a covering of newer strata is, as we have stated, the basalt plateau of the 

 north-east, embracing portions of the counties of Londonderry, Antrim, Tyrone 

 and Armagh. The cover in this instance consists of Cainozoic lavas and clays 

 and Mesozoic strata belonging to the Cretaceous, J urassic and Triassic, which 

 have been preserved from denudation beneath the lavas. This concealed area 

 is a rectangle about fifty miles long from north to south and thirty miles 

 wide. The Mesozoic sediments are in general only poorly exposed around the 

 margins of the basalt, so that little can be effected in the way of a study of 

 their thickness and character, with a view to drawing conclusions as to the 

 form of the floor on which they have been laid down. Fortunately the 

 evidence from the other two sources mentioned above is remarkably good, and 

 enables very definite conclusions to be drawn as to the areas in which concealed 

 coalfields will most probably be found. 



The most outstanding fact regarding this area is that it is traversed 

 by the south-westerly continuation of the central trough- valley of Scotland 

 which separates the Highlands from the Southern Uplands, and contains the 

 valuable coalfields of Fife, the Lothians, Lanark, and Ayrshire. The extension 

 of this remarkable feature into Ireland has long been recognized, but its 

 bearing on the probable existence of concealed coalfields beneath the newer 

 strata of Antrim has, 1 venture to think, hardly been appreciated. Kelly, 

 writing in 1857, 2 has, indeed, the following remarkable passage : — 



" This valley [i.e. the trough-valley of Scotland and Ireland] appears to have existed 

 before the deposition of the Carboniferous formation, and was a natural depression, in 

 which that formation was deposited. The S.W. strike of the valley of the Clyde is fair 

 across the channel to the county of Antrim, where the coal rocks reappear, and no doubt 

 are under the periniau and chalk formations below the great basin of Lough Neagh. 

 They emerge again at Coal Island in Tyrone, . . ." 



Final Report of the Coal Commission, Part ix, p. 18, 1905. 

 2 John Kelly : On the Subdivision of the Carboniferous Formation in Ireland. Jouru . 

 Geol. Soc. Dublin, vol vii, p. 247, 1857. 



