PROCEEDINGS OF SECTION C. 409 
I take for the first example the section on the western 
boundary, at the Upper Dargo River. The valley of the river at 
that place is almost coincident with what has been regarded as the 
line of passage of the normal Lower Silurian} rocks of the district 
into the metamorphic schists. The observations which I had 
made elsewhere caused me to feel very strong doubts as to there 
being any passage from the sedimentary formations to the 
crystalline schists of Omeo, and it seemed to me that this locality 
might afford some valuable evidence on the question. 
The sedimentary rocks at the Upper Dargo are an alternating 
series of highly-inclined greenish-coloured slates and sandstones, 
having a north-westerly strike, and being traversed by more or 
less auriferous quartz lodes. On the eastern side of the river 
these beds are found to be much corrugated, and to be minutely 
wrinkled with asilky lustre. Strings and small lenticular patches 
of quartz are also present in and across the corrugations. Herein 
one may recognise an early stage of metamorphism. 
In ascending the steep spur on the eastern side of the valley 
the rocks are all mica schists of increasingly marked character, 
becoming harsher, and with veins of glassy-looking quartz. The 
dip of the beds appears to be the north of east, at from 60 deg.— 
70 deg. 
At about 400 feet above the river there occurs a mass of diorite 
in the schists. It is composed principally of rather light-coloured, 
not very pleochroic amphibol, with a small amount of ideomophic 
plagioclase and quartz. From about this point the schists more 
resemble gneisses with a harsher texture, and are marked by the 
abundance in them of black mica (biotite). From here upwards 
it is not possible to say with any safety what is the position of 
the beds, but so far as I could make observations, the dip is 
probably in accord with that of the lower beds. 
In order to show the character of the beds from 400 feet up 
to 1250 feet, namely, to the summit of the spur above the level 
of the river, the following may be noted. 
As I have said, biotite increases greatly in the schists, until at 
about 600 feet much contorted foliations of black mica are very 
marked. Under the microscope the rock is a finely foliated 
contorted schist, composed of biotite, a little muscovite, grains of 
quartz, and here and there broken crystals of green tourmaline. 
I observed here also a white schist with schorl, which traverses 
the other schists. On examination, it proved to have been 
originally a dyke composed of orthoclase, quartz, and schorl, 
similar probably to felspathic dykes, which are common in the 
} The rock is a very fine-grained mica schist. The micaisin minute colourless flakes, 
which are arranged either longditudinally in the narrow foliatures or in smaller plumose 
groups or rosettes. In places there are narrow foliatures, or lenticular aggregates of quartz 
grains, In other places similar veins of quartz, in which are scattered plates of mica, The 
whole rock has been molecularly rearranged. assuming it to represent the argillaceous slates 
near at hand, in some of which minute mica flakes are very numerous. 
