116 
JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
considered as a simple rock, since, besides the conglomerate which is 
essential to it, it sometimes contains shales and limestones, and oc¬ 
casionally coal. The next bed in the order upwards is a limestone 
containing a few fossil remains, and known by the name of Mountain 
and of Carboniferous Limestone.” 
Professor Phillips, in his “Geology of Yorkshire,” gives a Table 
at page 11, in which he divides the Carboniferous system into three 
principal parts: the Coal Formation, Carboniferous Limestone, and 
Old Red Sandstone; and he says:—'“The Carboniferous system does 
undoubtedly permit itself to be considered in three series, characte¬ 
rized by the prevalence of coal, limestone, and Red Sandstone.” In 
his “ Geology” in the Cabinet Cyclopaedia, he adheres to the same sub¬ 
divisions, and calls it “ a triple system.” 
The descriptions given by those writers appear clear and satis¬ 
factory, and point out distinctly their idea of the position of the 
Old Red Sandstone; and I would say, their views on the subject 
do not appear to me to require any alteration or modification; and 
I therefore adopt the position and the type of that rock, as pointed 
out by them. 
In Ireland the Carboniferous formation is divided into a similar 
triple system; and though its subdivisions everywhere differ widely 
from each other in lithological appearance and mineral character, yet 
the whole system is characterized by the remarkable circumstances: 
—1. That the strata of which it is composed rest unconformably 
on whatever rock lies below them; 2. That they are covered uncon¬ 
formably by the overlying rock; and, 3. That they are parallel to 
one another, or lying, as it were, in one bundle: thus, though in 
three groups of different mineral character, yet clearly pointing to 
one geological epoch, in which the whole suite, from beginning to 
end, was deposited, without any great catastrophe or disturbance, in 
its position or succession. Wherever we can see a clear junction 
or a good section, we generally find the beds of the older, or under¬ 
lying rocks, thrown up on their edges, at a steep angle; while the 
beds of the Carboniferous system lie on them at a comparatively low 
angle, and often nearly level. 
The Old Red Sandstone may itself be divided into three parts, 
differing from each other chiefly in lithological appearance :— 
1. The first or lowest is usually a band of red conglomerate, com¬ 
posed of rounded pebbles of white quartz, brown quartz, purple horn- 
