Mr William Stevenson on the Origin of Granite. 171 
chiefly of quartz, with a little mica. A little to eastward, a 
beautiful, pure, flesh-red felspar has been erupted in three 
or four places. This, by combining with the micaceous 
schists, has become a splendid large-grained granite, con- 
taining many crystals of black tourmaline. 
7. Aberdeenshire. — At Cove (about five miles S.E. from 
Aberdeen) the junction of the granite with the primary 
schists is beautifully shewn. The appearances here presented 
are highly interesting and instructive, and seem quite to 
confirm the proposition stated in the beginning of this 
paper. The schists here are generally very distinctlj^ strati- 
fied and laminated, and dip to S.S.W. and S.W. at angles 
of 40° and upwards to near 90° They are much intersected 
by quartz veins crossing the strike from N.E. to S.W. They 
also contain numerous intercalated beds or stratiform masses 
of red felspar, some of which pass into a regular granite by 
acquiring quartz and mica from the adjoining schists, and 
all of them show more or less a tendency to become granitic. 
In some places the felspar is pure, in others associated with 
quartz alone, and again, in other places, with mica to the 
exclusion of quartz. The schists are metamorphosed from a 
finely laminated magnesian clay-slate to talc and mica slates, 
which again become gneiss in the vicinity of the granite, 
by the interlamination of felspar. Where the felspathic 
mass is considerable, a regular granite is formed by a mix- 
ture of the felspar with the quartz and mica of the schists. 
At the junction the granite is generally very large-grained. 
From this mass the veins and apparent beds exposed in the 
sea-cliff proceed. One of the veins is five or six feet thick 
at the bottom, thinning to about two or three at the top of 
the cliff. It is generally a medium-grained granite, but in 
many places almost wholly flesh-coloured felspar. A thin 
seam of large-grained granite (three-fourths of an inch 
thick, and almost entirely felspar and mica) occurs at the 
junction with the schist. Fragments of the latter are also 
enclosed in the granite in many places. The schists appear 
to have been simply argillo-arenaceous strata, metamor- 
phosed first into a sort of clay slate, then into mica slate, 
with the characteristic quartz layers ; next, by a higher 
VOL. IIT. z 
