RESEARCHES AMONG THE PALiEOZOIC ROCKS OF IRELAND. 139 
lies unconformably on the inferior rocks, and not one case do I know 
in Ireland where they are conformable. The base of the Old Red, 
therefore, forms an abrupt, distinct boundary line between the two. 
All the rocks in the vicinity of this line are resolvable into either 
the group above it, or the rocks below. I hope, therefore, I have 
made clear the conviction that is on my own mind, that there is no 
passage, or gradual change, between the lower and the upper sys¬ 
tem, and consequently no Devonian rocks in Ireland. I know that 
the reverse of this statement has been put forward years ago in this 
Society, and reiterated many times since. Even last year a paper was 
readhere, stating that the brown grits of Dingle are Devonian; but 
I look upon this as without foundation. Any grits, or slates, that 
lie between two bands of Silurian fossils, tbe whole being confor¬ 
mable, should be classed with Silurian rocks, as well as the sand¬ 
stones and shales lying between two beds of coal, should be put into 
the coal series. 
Indeed, it appears quite impossible to reconcile tbe Devonian 
system, as tabulated by Sir Charles Lyell, at p. 365 of his- Manual, 
with the appearances presented in Ireland, and no doubt this is the 
best authority now extant. In this work the Carboniferous forma¬ 
tion consists of only two members,-—the coal series, and the moun¬ 
tain limestone. The Old Red Sandstone, which forms a natural 
division of the formation, is cut away, and classed with lower rocks, 
thus 
Upper Devonian. 
a. Yellow sandstone of Dura Denn, Fife. 
b. Red sandstone and marl, with cornstone of Herefordshire 
and Forfarshire. 
Paving and roofing stone, Forfarshire. 
Upper part of Devonian beds of South Devon. 
Lower Devonian. 
Gray sandstone, with Ichthyolites, Caithness, Cromarty, and 
Orkney; lower part of Devonian beds of South Devon, and 
green chloritic slates of Cornwall; limestone of Gerolstein, 
Eifel. 
Under these are the Silurian rocks, comprising the tilestone 
of Brecon, the Ludlow and Wenlock limestones and shales* 
the Caradoc sandstone, and Llandeilo flags. 
