KiNAHAN — Killary Bay and Slieve Partry Silurian Basin. 715 
whinstone, there were felstones and quartz rocks ; but curiously, al- 
though they can show you the so-called untorn -up whinstone," they 
never could show the untorn-up felstones or quartz rocks. 
In the Sutherland, Boss, and Cromarty " Old Eoy," similarly as in 
all other tracts of metamorphosed rocks that I have examined, in the 
Old and ll^'ew World, there are metamorphosed dykes more or less 
transverse and crossing the general structure {stTatification of the 
County Eocks. Invariably the foliation in these dykes has strikes and 
dips quite distinct to those of the associated rocks. This to me is a 
simple phenomenon, because, as pointed out years ago by David Forbes, 
foliation is induced by the most prominent original structural planes. 
Here, therefore, we have in the County Eocks the foliation induced by 
the most prominent original structure, let it be cleavage, lamination, &c. ; 
while, in the dykes, it was induced by their most prominent structure, 
which, in general, is more or less parallel to the walls of the dykes. 
Such simple explanation, will not, however, be allowed by "the 
shearers," as they insist that the foliation in the County Eock is due 
to a shearing force coming in one direction, while the foliation in the 
dykes is due to a subsequently shearing force coming in another direc- 
tion ; but they fail to explain how the latter force confined itself solely 
to the dykes, the walls of which are still intact. 
Eefore making such sweeping assertions they should visit such 
regions as that of Lake St. John, Eastern Quebec, or even the Lough 
Conn district, E. Mayo, Ireland. In both these widely-separated 
places the latest foliation seems to be in the main due to shearing. 
And its strike, let it be in granitic rocks, in hornblende rocks, or in 
schist or gneiss, is always in one direction, although its dip in places 
may slightly vary. In contradiction to the general theory of "the 
shearers," it maybe pointed out that in these excessively altered rocks, 
some of the leaves in the IS'orians of St. John's being over 3 feet long, 
the boundaries of the intrudes have been very little distorted. In the 
St. John's district it is quite easy to trace the boundary of the JSTorian 
and the dykes from it ; while in the Lough Conn district, Co. Mayo, 
the boundaries of the granite coui'ses in the gneiss and the boundaries 
of the masses of hornblendite that occur as inliers in the granite, are 
nearly intact, they only being a little serrated.^ 
1 In the granite north of Galway Bay there are some dykes of a rock that must 
be called " typical schist." The walls of these dykes are regular and well-deHued. 
On the other hand, in the rocks of the Letterkenny district, county Donegal, which 
are only sub-metamorphic, shearing has played queer pranks, di awing out tongues 
