Address to the Royal Geological Society of Ireland. 121 



will frequently be perfectly barren. However, not all tracts of 

 quartzite are so, as associated with such rocks will sometimes be 

 found other schists, or the quartzite may not be pure, thus in 

 part counteracting the bad qualities ; as a general rule, such lands 

 unless very favourably situated, as near a large town or the like, 

 will scarcely be profitable as tillage land except in patches, but 

 might be made remunerative if planted with trees. An instance 

 of such ground is presented by the Government lands of the 

 Forth Mountains, county Wexford, parts of which would pay as 

 tillage, but the greater proportion is more suited for planting. 

 Land of this class to be either tilled or planted, ought to be sub- 

 soiled and cleared of stones, and the low portions or hollows 

 should be drained. 



Soil made up solely of granite debris is very cold and poor and 

 is not much improved when mixed with peaty matter ; the debris 

 of other rocks, however, when mixed with growan (rotten granite 

 or granitic sand) changes its nature, more particularly if the 

 foreign substance is limy matter, especially if in the condition of 

 marl. The rich lands of Carlow, on the flanks of the Leinster 

 mountains, owe their character, in a great measure to the mixture 

 of granitic and limestone debris. Elsewhere are also found in 

 granitic area patches of good land more or less due to a similar 

 cause ; as, for instance, in the Gal way granite hills, on, or adjoining, 

 accumulations of limestone drift. 



The highly silicious felstones give debris more or less like 

 quartzite and granite ; tracts of such rocks are, however, of limited 

 extent. Basic felstones and whinstones, especially the friable 

 varieties of the latter usually weather into good and rich soils 

 Often, however, although the soil may be good it is so thin as to 

 be unsuitable for tillage, and the land must be used for pasture. 

 The accompanying tufl"ose rocks, also, are often good soil producers. 

 The richness of some portion of the county Limerick is due to the 

 admixture of the debris of these eruptive rocks and limestone ; 

 while in some of the mountains, such as Slieve Partry, county 

 Mayo, the detritus from a course of a friable whinstone or tuff 

 forms a strip of good land. When such rocks occur in mountain 

 regions, their debris might be profitably utilized in improving the 

 land in their vicinity. 



