58 
In Scotland there are tvro old red districts, one south, 
and the other north, of the Grampians. The beds of the 
southern region are divided into three groups. The lower lies 
conformably upon the upper silurian, the middle lies uncon- 
formably upon the lower, while the upper lies unconformably 
upon the middle, but passes upwards conformably into the 
carboniferous rocks. In the northern region also three 
divisions are recognisable, but there is no unconformability 
between them. The lower rests unconformablv upon lower 
silurian rocks, and the carboniferous rocks are absent. 
In the South of Ireland, the beds which intervene between 
the silurian and carboniferous systems are naturally divided 
into two sets ; the Dingle beds, consisting of coloured grits, 
slates and conglomerates, apparently resting conformably 
upon and passing gradually downwards into the representa- 
tives of the Ludlow rocks ; and a set of red sandstones and 
conglomerates resting unconformably upon the Dingle beds, 
and passing insensibly upwards into the base of the carbon- 
iferous rocks, which here consists of a vast series of grits and 
slates, known as the " carboniferous slates." 
In Devonshire, the series of beds which occupies a posi- 
tion corresponding to the preceding, differs entirely from it 
both in mineral character and in fossils. It is a marine 
formation — slates, limestones, and marbles ; and contains 
abundance of shells and corals. It was first recognised as 
contemporaneous with the old red sandstone of the north b}' 
Lonsdale, Murchison, and Sedgwick, in 1836, after the recog- 
nition of the anthracitic shales and sandstones of North Devon 
as carboniferous. In 1866, Mr. Jukes read a paper before 
the Creole gical Society, in which he maintained that the beds 
which underlie the anthracitic beds of North Devon were not 
of old red sandstone age, but were contemporaneous with the 
carboniferous slates of the South of Ireland. PalLcontological 
evidence, however, is in favour of the former view. 
