-140-

«7 +2

bv the writer to cut the

similar to these and not
They appear, however, to be

somewhat less chloritized end altered. ‘The fact that these rocks

rest sea gees . tive zie 2
st unconformably on grenitic rocks cutting the older volcanics

has led the writer to consider them as Cretaceous or possibly
late. Jurassic. They may occur extensively in the Topley section.
They would be unfavourable for mineralization of the types
associated with the older granitic rocks upon which they rest.
The intrusive rocks largely fall into four main groups,
two of which are probably Jurassic and the other two Tertiary.
One of the older groups is largely diorite and gneiss. South of
Silver Island landing on Babine lake, in Taltapin district,
andesites grade to schists and these appear to grade to diorite
gneiss and to diorite. Diorite, which is commonly dark grey, is
of different ages and in places sharply cuts the gneiss and
schist. In places the gneiss is very weil banded and shows a
wide range in composition from pegmwatitic and granitic materials
to hornblendite. There is no clear-cut evidence that magmatic
differentiation in situ was a major factor in development of this
complex, though some seems to have occurred. Much of the material
appears to have developed by alteration and replacement above and
at the upper limit of a magma chamber. Prospectors state that
this type of material occurs abundantly in areas between and near
Divide lake and Taltapin mountain and farther east. The second
group of older, Jurassic(?) intrusives is of granite which in
many places grades to granodiorite and even to quartz diorite.
It cuts the diorite and is younger, but could possibly be
ene: to it. The rock renges from red and white to dark grey,
closely approaching the dior" IG ranges from very coarse

material, like pegmatite, co Tine grained; in places it is