426 Scientific Proceedings, Royal Dublin Society. 
“ the richest soil ” which Wakefield “ever saw turned up with 
plough ”—are over limestone, but being drift soil it is usually 
deep, and contains an admixture of other rock débris.!_ The bene- 
ficial effects accompanying the intermingling of various kinds of 
rock detritus is dwelt upon by Dr. Fream,’ who points out that the 
most fertile veins ofland in England follow the junction of different 
geological formations. In our own country the proverbial fertility 
of the Golden Vein in Tipperary and Limerick is doubtless due to 
the mingling of materials derived from the Silurian and Old Red 
Sandstone hills, the Galtees and Slieve Phelim on either side, with 
those derived from the limestone of the valley, as well as from the 
acid and basic igneous rocks which there penetrate the limestone. 
The Glacial deposits of Ireland are distinguishable as Upper 
and Lower Boulder-clays, both of which are frequently to be met 
with in the same section, and inter-glacial beds, which are strati- 
fied sands and gravels occasionally to be seen between the two 
Boulder-clays. These beds, known as “ Middle Sands and 
Gravels,”’ though frequently covered with Upper Boulder-clay, 
are not often to be observed resting upon the Lower ; and in many 
cases they may be regarded as washed or rearranged representa- 
tives of the latter Boulder-clay. Throughout wide tracts over 
the central plain, and on the flanks of the Dublin and Wicklow 
mountains, they form the surface; in which case the soil is 
gravelly and porous. The Upper Boulder-clay also frequently 
yields a porous soil, being often rudely stratified, and con- 
taining layers of sand. The Lower clay not only is now of 
great thickness in many places, as may be seen in each of 
the four provinces, but seems at one time to have had a very 
wide extension over the country. In very many places it is seen 
to consist chiefly of limestone débris, drawn probably from the 
great central plain; and to this fact must be attributed the 
fertility of the country on each side of the Leinster granite 
range, where the limestone drift covers some 900,000 acres of 
Dublin, Wicklow, Wexford, Waterford, Carlow, and Kilkenny. 
The solid crust is there formed of Silurian and other rocks equally 
incapable of yielding so fruitful a soil. The same may be said of 
1 See Nos. 1-9 in the Table at the end. 
2 « Soils and their Properties,’ pages 104, 105. 
