Mr. Weaver on the Geological Relations of the South of Ireland. 3 



the principal chain (see Sketches (a) and (b) in Plate i.), may serve to illus- 

 trate the general forms^ structure, and connection of the mountain and hilly 

 ranges with each other. In determining the geographical limits of the forma- 

 tions I have endeavoured to be exact*. 



(3.) The Southern and greater portion of our field of inquiry, is composed 

 of a transition tract ; its northern boundary being formed, both in the eastern 

 and western quarters, by carboniferous limestone associated, more or less, with 

 the old red sandstone ; while in the central part of the border, a coal country 

 is found directly conjoining with the transition series. The old red sandstone 

 both on the east and west, as well as in the northern portion of the field, attains 

 to considerable elevation, passing in its descent beneath the more level surface 

 of the carboniferous limestone ; and the limestone here, as in other parts of 

 Ireland, is surmounted by an elevated and extensive tract of coal measures. 



* See the annexed Geological Map of the South of Ireland (Plate ii.). In this Map I have cor- 

 rected a few particulars in the south-western extremity of my former Map of the East of Ireland. 

 Both are drawn on the same scale. 



That the geological inquirer may more readily seize the connection between the East and South 

 as well as with the North and West of Ireland, I have added a small skeleton map as an Index to 

 the geology of the whole island (See Plate ii.). In this the principal formations are distributed in 

 groups under the heads of the granite, mica-slate, clay-slate, greywacke and slate tracts, in which 

 these rocks respectively predominate ; but greater detail is given to the carboniferous series, as its 

 members generally appear in a distinct order of succession in the physical structure of Ireland. 

 Then follow the new red sandstone, lias, greensand, and chalk, in one group, succeeded by the 

 overlying trap as the last link of the chain, other formations later than the chalk appearing to be 

 wholly wanting in Ireland. 



With respect to the North of Ireland, I have availed myself in these outlines, in aid of my own 

 local knowledge, of the excellent memoir on the North-East of Ireland by Dr. Berger, the Rev. 

 W. D. Conybeare, and Professor Buckland' ; and of the valuable Reports en the coal tracts of 

 Connaught and Ulster by Mr. Griffith^, to which works it may be sufficient to refer for the requi- 

 site details. All that seems necessary on the present occasion is to indicate the prevailing forma- 

 tions in the primary tracts of the West of Ulster and Connaught. In both of these the chief con- 

 stituents are a base of granite, or syenitic granite, supporting mica-slate and quartz-rock, with pri- 

 mary limestone, greenstone, hornblende-rock, hornblende-slate, and clay-slate. In Galway white 

 imestone occurs in the mica-slate both in its simple form and intermingled with serpentine, in the 

 latter case constituting a beautiful green marble. And in Donegal, in particular, the white limestone 

 approaches to the character of statuary marble, apparently suited to the purposes of the sculptor. 



The geographical boundaries of the several geological groups will be readily apprehended by 

 comparing the skeleton map with a common Map of Ireland ^. 



' Geol. Trans., First Series, vol. iii. p. 121 et seq. 



" Geological and Mining Reports of the Connaught and Ulster coal districts. 



3 The Public look with expectation, to Mr. Griffith's promised Geological Map of Ireland. 



B 2 



