Correspondence. 319 
where biotite specially tibounds. In the same mass are distinct 
rounded fragments of fine gray gneiss, feldspathic quartzite and white 
quartz. The fragments are often the size of a man's head and larger. 
The quartz fragments have sharp contours ; those of feldspathic cjuartz 
are less distinct ; while the gneiss fragments are welded into the sur- 
rounding rock, often appearing simply as dark patches. In the north- 
ern portions^ the groundmass assumes a parallel structure, and gradu- 
ally merges, by loss of fragments, into common granite. The author 
supposes that the rock was originally puddingstone, in which the 
fragments have mostly consisted of gneiss and granite. Those only 
have been left that contained most quartz ; the rest have changed into 
a granitic mass. 
A fine-grained diorite is described, interwoven with innumerable 
granite veins of various ages. The veins are so welded into the diorite 
that the whole assumes the appearance of a hornblende gneiss. In some 
places fragments of different miueralogical composition are enclosed, 
without order. The author suggests that a formation composed of 
difTerent varieties of rock may have been broken to pieces, and these 
by motion in the fluid granitic mass, mingled together. Many exam- 
ples are described of granites enclosing fragments of other rocks. A 
case is mentioned in which a mass of gneiss is changed by granite 
veins, into a breccia. The fragments are flattened as if by pressure. 
The rock is traversed by a schistose, fine crystalline dike consisting 
of hornblende, biotite, chlorite, with quartz as an interstitial filling. 
The schistosity runs parallel with the flattened fragments in the sur- 
rounding mass. 
In some of tlie dioritic regions, the diorite is interwoven with innu- 
merable granitic dikes and veins. Where the sides of the granite 
dikes can be seen, they are grooved in the direction of the stretching. 
The dikes in general, follow the foliation of the diorite, and they some- 
times surpass in volume the dioritic rock. A person unacquainted 
with the general geological structure of the country might imagine 
veritable stratification. 
In reference to the origin of some of the granitic rocks and other 
eruptives. Dr. Reusch says : "The quartz eye-gneiss of Karmoeu and 
the granite of the Bommelo contain interbedded masses of fragmental 
rocks merging into the surrounding massive rocks, and making it 
probable that the latter were also originally clastic, as before suggested 
in reference to some of the (Silurian) gneisses of the Bergen peninsula." 
He thinks the various non-gneissic masses included in the granites are 
the remains of rocks originally interbedded in the fragmental rocks 
from which the granite originated. Respecting gneissic masses in- 
cluded or interbedded, he is in doubt; but he inclines to think them 
structural varieties of the granite ; since, for most of the comparatively 
massive gneiss-granite, it is diflicult to assume another origin ; as we 
find all transitions to varieties exhibiting quite characteristic granite 
structure. Nevertheless, we find central masses of granite undoubt- 
