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LIY. 
OT^ THE XILLAEY BAY AND SLIEYE PAETEY SILURIAN 
BASIN, ALSO NOTES ON THE METAMORPHIC ROCKS 
OF NORTH-WEST GALWAY (YAR-CONNAUGHT). By 
G. HENRY KINAHAN. 
[Eead January 12, 1891.] 
In a Report published in these Proceedings (2nd series, voL iii.), and 
read December 7, 1881, I showed that the Silurians of Killary and 
Slieve Partry accumulated unconformably, to the more or less meta- 
morphic rocks in the regions to the northward and southward. But 
this country has recently been visited by Messrs. A. Geikie and Peach, 
whose statements in connexion therewith are contrary to the facts as 
stated by me. Some of these have not been printed, but others 
appear in the " Proc. Roy. Institution of Great Britain," vol. 
xii., part iii., No. 82, pp. 528, et seq. 
The printed statements will hereafter be quoted ; but previously to 
doing so we will consider some others relating to the Killaiy Silurian 
Basin. It should be mentioned that Dr. Hull's published one-inch, maps 
of the district are rather conflicting, as on them similar rocks and 
groups of rocks, on adjoining maps, are differently lettered and 
coloured ; in many places the important dips of the strata are left 
out, or misplaced, or the dip of the cleavage has been substi- 
tuted ; while English group names, inapplicable to the Irish rock 
groups, are used, thereby adding to the confusion. 
The south boundary of this Silurian basin, in general, is more or 
less complicated, and in places would be hard to determine were it not 
for the decided difference between the rocks of the two formations. 
This boundary, however, is allowed to be correct, except to the 
north of Kilbride Bay, an arm from the S.W. of Lough Mask. But 
my northern boundary is stated to be a myth, and also the small 
inlying exposures to the north and south of Killary Bay ; while 
all the rocks from the south boundary northward to Clew Bay 
belong to one group ; the sole difference between my Silurians 
and my Ordovicians being that the latter are in part metamorphosed. 
