14 
To the Eastward are a series of undulating hills, with here and there a rough 
face of rock or a deep well-marked valley extending as far as the eye can reach. 
This is called the Great Antrim Plateau, and is of great interest, as it is the only 
known lava flow in West Australia. 
Both to the North and South of this table-land the Devonian and Carboniferous 
rocks are well developed, but on following the Ord River further North the Meta- 
morphic rocks again outcrop, following the river in a North-Easterly direction to 
the Burt Range, where they disappear beneath the Carboniferous formation, which 
extends as far as the coast, and all the way down it from Cambridge Gulf to 
King Sound. 
To the South of this district stretches Warburton’s Great Sandy Desert, which 
is an inland plateau, believed to be about 5,000 feet above the sea. It is covered 
with parallel ridges of light red sand rising to 50 feet in height, and about 400 
yards apart; these rest upon clay and gravel, the pebbles of which are smooth and 
water worn. 
The North-West District. 
This district extends along the North-West coast, from Point Cloates to the 
80-Mile Beach, and Eastward to the boundary of the Northern Territory of South 
Australia. At the heads of the Fortcscue and DeGrey Rivers, there is a high 
table-land of carboniferous age with numerous basalt dykes. 
Several large rivers take their rise on this table-land, flowing in a Westerly 
and North-Westerly direction, cutting deep gorges through the horizontally 
bedded carboniferous rocks, exposing the underlying crystalline series. Further 
on they pass over flats, bouuded by rough sandstone ranges, and so on by deep 
ravines through rough broken hills of schists, slates, sandstones, quartzes, conglo¬ 
merates, with numerous amygdaloid dykes and quartz reefs, many of which have 
proved to be auriferous. 
These rivers next flow over the large alluvial plains of the coast, rising from 
winch here and there are bold hills of trap rock and small peaks of quartz 
granite, and ironstone, around which soft calcareous slates are often met with’ 
rising to the surface, but never forming hills much above the level of the plains. ’ 
These plains extend to the sea coast, where they are fringed by mangrove 
swamps, except where trap rocks extrude and form a bold rooky coast. & 
The ainygdaloids in many places split up iuto rough blocks, which become 
red or black on the surface, and then present the appearance of a huge heap of 
stones, without a trace of soil or vegetation. They contain vast numbers of agates 
calcite crystals, and other enclosures, so that it would he advisable to prospect the 
streams running through them, for precious stones. 1 1 
Further to the Westward the rivers are not so large, rising in a range which 
runs North-West and South-East, forming the water parting between the rivers 
flowing West and those flowing North. This range is formed of crystalline rocks, 
capped with horizontally bedded sandstone. It presents bold cliffs to the open 
plain or lower table-land lying to the North, which is occasionally broken by 
isolated sandstone lulls often containing jasper and agate, while the rivers ox 
pose beds of conglomerate and breccia beneath the sandstone. Below this table 
laud the country is more broken, covered with small ranges and isolated hills, 
capped with sandstone, between which the rivers open out into good sized flats. 
The coast ranges, rising about 700 feet above the sea, are rough broken hills, 
composed of hornblende schists, quartzite, conglomerates, shales, limestones with 
amygdaloids, dionte, granite, actmahte, and tourmaline dykes and. lodes of 
galena, auriferous antimony, ferruginous copper ore, ironstone quartz and 
jasperv veins. ’ 1 f 
