7 
b 
; 
. 
4 
Kitror— The Distribution of Drift in Ireland. 423 
lying chiefly in the low grounds, where, however, the naked 
rock frequently presents itself over small areas; and in places 
rising to heights of 1350 or 1400 feet} on hill sides, softening the 
asperities of contour, and otherwise modifying the landscape. 
Above the 1500 feet contour line extends an area of some 
800 square miles, which may be regarded as waste mountain land. 
About 836 square miles between the 1500 feet and 1000 feet con- 
tours, contain very little Drift, well-nigh all the Drift falling below 
the latter contour, where it covers a large portion of the 30,836 
square miles,’ between this contour and the sea, probably over 
20,000 square miles, including portions concealed by bog. This is 
shown by stippled dots on the published one-inch map of the 
country, which is accompanied by LJxplanations, containing 
general descriptions of the Boulder-clays. Detailed descriptions, 
however, are not published, though notes are given on the 
unpublished six-inch maps (which may be seen by the public 
at the Geological Survey Office), describing the superficial drift 
in many places: and such notes are of great value from an 
agricultural point of view; for fertility in Drift-covered areas 
is more dependent upon the character of the transported materials 
than on the nature of the rock which they conceal, and for the 
representation of which alone colouring is used on the published 
map. Mr. Albert Pell says, in the Journal of the Royal Agricul- 
tural Society of England (Part I. 1890) with reference to this 
subject: “It is with the surface that the farmer has to do. A 
geological Hl Dorado of fertility may be below him at a depth of 
4 feet; but if the space between that and the sole of his plough, 
or the hoof of his live-stock, be taken up by a layer of Boulder- 
clay, it might as well be on the other side of the world, for all the 
good that it will do him.” A map which would be likely to meet 
the requirements should indicate the superficial drift which forms 
the soil, and in most cases the subsoil, by light tints of colour, 
decided by the materials of which the Drift is chiefly composed, 
heavier tints being appropriated to areas of uncovered rock. 
The light tints might be lined diagonally to represent a different 
1 Rey. M. Close records the occurrence of transported blocks on the Dublin moun- 
tains, at a height of 1760 feet. See Paper Jour. Roy. Geological Society, Ireland, 
vol. for 1866, p. 10. 
* Ascertained by the Ordnance Survey Staff for Sir R. Kane. 
SCIEN. PROC. B.D S.,-VOL, VIII., PART VY. 2H 
