33 
In spite of tlie large area over which these formations extend, very few beds 
of the series are exposed, owing to the fact that they have not been disturbed or 
faulted, and are almost always nearly horizontally bedded, but where they do dip 
slightly in one direction, they are invariably found in a short distance to dip in the 
opposite, whilst the streams have not cut sufficiently deeply into them to expose 
much below the magnesian limestone. 
Devonian. 
This formation is largely developed in the Carr-Boyd Ranges, also in a wide 
belt, which runs South from Saw Range to the Lubbock Range, a distance of about 
200 miles. The narrow, abrupt Albert Edward Range, which is about 100 miles 
long, is formed by the outcrop of rocks of this age. The Barrier Range, to the 
Southward of the Leopold Range, appears now, from the determination of the 
fossils, to be also of this age. 
Silurian. 
To this period have been ascribed those clay-slates, limestones, sandstones, 
cpiartzites, and conglomerates, which are not highly metamorphosed. They occur 
in many places throughout the Colony, forming large ranges. 
The Stirling Range, to the North of Albany, is probably of this age, and this 
formation is also to be met with in the Kimberley district, but. up to the present 
no fossils have been identified. 
Cambrian. 
In this group are classed all the older series of rocks that have not been too 
highly altered to preclude the possibility of organic remains being discovered in 
them. Two fossils have been determined as belonging to this age, in the Kimberley 
district, where these rocks extend in a North-East and South-West direction from 
the Burt Range to the Southward of Mt. Dockrell, and it is in this belt that the 
principal gold discoveries have been made. In places the rocks are highly altered, 
but this is mostly from purely local causes. 
The clay-slate auriferous belt of the Colony may also be of this age, but this 
cannot, at present, be determined. 
AZOIC. 
Archaean and Crystalline. 
Crystalline .—These rocks are met with in a belt which runs from the South 
coast to the Upper Murchison River, at a distance of from 10 to 50 miles from the 
west coast. They also occur in the Northampton, Roebourne, and Kimberley dis¬ 
tricts. With these rocks are associated mineral lodes containing copper, lead, 
zinc, tin, and auriferous pyrites. 
The Hornblende rocks of this Colony are very characteristic of this series. 
They are met with most abundantly from North to South, and vary immensely in 
colour, structure, and external character; some at first glance have the appearance 
of clay-slate, but on fracture exhibit a structure similar to diorite, while others 
again only contain green grains of that mineral disseminated throughout a quartz 
matrix, and these are continually being mistaken for copper, nickel, or silver. 
IGNEOUS. 
Volcanic. 
At Bunbury and Cape Beaufort columnar basalt occurs, and though only 
exposed at the coast, it probably extends inland under the modern Tertiary beds. 
c 
