Anniversary Address to the Royal Geological Society. 491 
conflicting. Stratigraphically, the rocks north of the Killary, at 
Creggaunbaun, those south of the Killary, at Gowlaun, and those 
to the eastward, at Kilbride, on Lough Mask, and adjoining the 
north shore of Lough Corrib, seem to be the oldest ; while the 
rocks elsewhere, although lithologically and _palontologically 
different, nevertheless correspond chronologically, their different 
characters and fossils being solely due to the different circum- 
stances under which they accumulated. 
If we attempt to calculate their thicknesses in the style so 
frequently followed, errors will be innumerable. The maximum 
thickness, from stratigraphical evidence, occurs in N.W. Galway, 
south-west of Killary Bay; but, from palzeontological evidence, 
the oldest rocks of this area ought to be of the same age as the 
rocks in the second group at Ballaghaderreen, county Mayo 
rocks which, stratigraphically, must be on or nearly at the horizon 
of the Salrock Beds, that is, the highest group of Silurians in 
N.W. Galway. 
Calculating the thickness of these rocks by their bedding, also 
similarly misleads, especially in the Toormakeady district, as 
there the conglomerates have a general westerly dip, and are ap- 
parently of great thickness ; but the Formnamore Mountain rocks, 
which seem to be above them, lie nearly directly on the continua- 
tion of the eurites, which underlie the Toormakeady conglome- 
rates ; thus showing that the Toormakeady conglomerates and 
the rocks of the Formnamore Mountains are contemporaneous 
accumulations ; their difference in character being solely due to 
the different circumstances under which they were deposited. 
In South-west Ireland (Waterford, Cork, and Kerry) is the 
Irish portion of Geikie’s “Welsh Lake Basin.” Here, as in 
Devonshire and the adjoining portions of England and Wales, 
there are remarkable and rapid changes, both lithological and 
paleontological. As, however, it is probable that the rocks of 
this country will be the subject of papers brought before the 
Society during the present year, I shall not now enter into the 
discussion of them. 
A study of the Irish Mesozoic rocks, and a comparison between 
them and those of England and the Continent, gives interesting 
results. These rocks occupy only a limited area in Ireland, and 
are confined to the province of Ulster. They are of inconsider- 
able thickness, and forma continuous wnbroken sequence from the 
