estan | 
XX.—THE OLD RED SANDSTONE (so cattep) OF IRELAND 
IN ITS RELATIONS TO THE ONDHRLYING AND OVER- 
LYING STRATA; sey G. H.  KINAHAN,. m.p.it.a,. &e. 
[ABRIDGED.]| Witra PLATES 6 anp 7. 
[Read November 18, 1878. j 
A QUARTER of a century ago it was a disputed question whether 
the “ Old Red Sandstone” was a separate formation or not ; about 
that time, or a few years later, the subject engaged the attention 
of the Geological Section of the British Association. It would 
seem that, as far at least as the Irish Old Red Sandstone is con- 
cerned, a decidedly negative answer must be given to the 
question. 
The argument consists of two divisions, viz. :— 
(1). There is a wide unconformability between what have been 
regarded by some as the lower and the upper portions of this 
supposed formation; while the lower is joined conformably to 
the underlying Silurian,* and the upper is similarly connected 
with the overlying Carboniferous strata. The lower part is, 
in fact, Silurian and the upper is Carboniferous. 
(2). The “Old Red Sandstone” beds, though usually below 
the base of the Carboniferous strata, are not always so, but are, 
in various places, on the horizons of different parts, sometimes 
upper parts of the Carboniferous Limestone, and are sometimes 
actually interstratified therewith. 
(1). The former of these arguments involves the necessity of a 
short historical sketch of the controversy respecting the age of 
- the rocks in certain districts of Ireland. 
When I joined the Geological Survey, Sir R. Griffith had 
mapped the older rocks in West Cork as of Silurian age; while 
Jukes was inclined to class them as “Old Red Sandstone.” 
Plant remains were found in rocks of the same series in the Kil- 
larney district, in the summer of 1855, and farther westward near 
Valencia, in the following year, by the fossil collector, C. Galvan. 
* It should be borne in mind that ‘‘ Cambro-Silurian ” and ‘Silurian ” mean respec- 
tively, in this paper, the formations usually called Lower Silurian and Upper Silurian. 
