KiNAHAN — Killary Bay and Slieve Partry Silurian Basin. 713 
The absurdity of the latter to me is self-evident, as can be ocularly 
proved both in counties Wicklow and Donegal, as in these areas you 
find, in the metamorphic rocks, courses that have a central horn- 
blendic gneiss, or hornblendic rock rib, with schistose margins ; while 
these courses, when traced into the unmetamorphic areas, are found to 
have a diorite, diabase, or allied rock rib, with tuffoid margins. In 
the counties Gralway, Mayo, "Wicklow, and Wexford, I have found 
whinstones and eurites passing gradually into conglomeritic or fine 
tuffs ; and the latter into sedimentary rocks ; the graduations being so 
imperceptible as to defy the most acute observer to say positively the 
exact places where one class of rocks ends and the other begins.^ 
Consideration. — In unmetamorphosed regions, in connexion with 
intrudes, there are the " Baked rocks." These are, for the most part, 
granulites, leptinites^ hornstone, and such like felsitic rocks. 
Associated with the " TJntorn-up," ''Old Boy," of Sutherland, 
Scotland, the hornblende rock in the older metamorphosed rocks of 
Ireland, and the hornblende rocks in the Ontarians of Canada, there 
are highly felsitic gneissose rocks. It may be asked what brought 
them there ? and what was their origin ? I would suggest that in all 
these situations originally they were ''Baked argillaceous rocks" that 
subsequently were metamorphosed.^ 
Of course, in metamorphic regions the shearing has modified the 
original structure, and indeed in places where it was intense, oblite- 
rated them; because, as pointed out by myself and others, in the 
granitoid gneiss the foliation becomes perpendicular, or nearly so.^ 
Furthermore, in all conglomeritic rocks, foliation, and, in general, 
even cleavage, changes the outlines of the inlying pebbles, elongating 
them more or less, I could point out in the county Donegal granite 
pebbles, adjoining an upthrust place, that have been elongated to an 
extraordinary extent ; while in the layers immediately above, the 
pebbles are in their normal state. Wyley and Haughton long since 
^ The Great Eock, Arklow, county Wicklow, is one of these puzzles. Of it 
there are in existence maps by Oldham, Smythe (?), Jukes, Du Noyer, and myself, in 
none of which is the mapping the same ; while in some of them the rock classifi- 
cation is most different. 
^ In fact, in places in the Co. Wicklow it is self-evident that some of these 
" Contact gneisses" were originally *' Baked rocks." 
^ From my own experience, and from the writings of others, I at one time 
considered this to be an unexceptional rule ; but recently in the Malin promontory, 
Innishowen, Co. Donegal, I have found granitic gneiss in which the foliation is 
nearly horizontal. 
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