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half that elevation Leichardt is said to have found on his descent from a plateau, precipices 800ft. high, 
hut this is now known to he an error in transcribing his notes. The name of “ desert sandstone” is unfor¬ 
tunately chosen for these tablehills or flat-topped ridges. Sandstone there is in abundance, besides 
ferruginous sandstones and sandstone conglomerates, but they are not always in the cliffs, or only form a 
portion of them. Nearly all the cliffs are capped with compact magnesite, or carbonate of magnesia, from 
10ft to 40ft. in thickness, sometimes ferruginous, or quite pure and white. The cliffs are made up of 
various formations, and it is incorrect to call them desert sandstone”. Here are the proofs. At Yam Creek, 
about two miles south from the telegraph station, the line passes through a gorge, bordered on each side by 
precipitous cliffs, varying in height from 130ft. to 200ft. The bottom of the valley is 335ft. above the low- 
water level of the sea. At one place where I ascended the cliffs they were 130ft. high. Of this 90ft. was 
granite, lOft. water-worn quartz conglomerate; ferruginous, magnesian sandstone, 16ft.; pure white 
magnesite, 14ft. Two miles farther the cliffs were 143ft high; of this, 80ft. were granite, and 50ft. a 
highly ferruginous sandstone, horizontally stratified. 
At the head of the Mary the cliffs were 150ft. high—30ft. of this was a fine-grained white sandstone, 
formed of wind-blown sand, the grains under the microscope being rounded and abraded like the sands of 
the Sahara. Above this was 100ft. of pure white magnesite; the valley was composed of paleozoic slates 
and feLsites—a compact mixture of quartz and felspar, without any traces of crystallization. Other instances 
will be given in the body of this report. At the gorge of Yam creek, the tableland is a mere ridge. At 
McMinn’s bluff (270ft. above the plain) it is an outlier broken up into detached hills. It is the same at 
Mount Shoobridge. At the head of the Mary the cliffs are about 200ft. high ; then there is an inclined 
plain rising 100ft. higher in six miles; then for four or five miles an inclined plain descends 40ft. a mile 
until Kekwick’s springs, on a tributary of the Katherine, are reached. 
Again: on the heads of the Katherine a sandstone tableland was ascended to a height of 250ft., but it 
was a mere ridge with a valley 50ft. deep on the east side, with large springs of fresh water giving rise to a 
creek — crossing this led to an inclined plain of four miles, with a fall of about 25ft. to a mile. This brought 
us to a gully—the head of Maude creek—where we were, in about three miles, almost on the level of the 
Katherine, and in auriferous country again. It will be seen, therefore, that, as far as I have seen, “ the desert 
sandstone” (so called) is confined to numerous small patches of a newer formation of moderate thickness which 
does not cover the older rocks to any large extent. Yet this character would not be suspected from its aspect 
as seen from a distance. I don’t wonder in the least at earlier explorers having been led into error with regard 
to it. When one ascends to the summit of any moderate elevation, the sloping base, white cliffs, and flat 
summits of these hills are conspicuous objects, and there extends from them level plains of apparently un¬ 
limited extent. But none of the hills are high enough to command an extensive view; if they did, other 
hills would be seen cropping out. 
The mistakes which have occurred have been for want of careful measurements, or from giving descriptions 
from distant views rather than from actual exploration and a close examination of the nature of the rocks. 
I have also had the advantage of the 125 miles of levels taken for railway purposes. It must he also borne 
in mind that the magnesian and sandstone formation never rises to the height reached by the paleozoic and 
metalliferous rocks. Thus Mount Wells (mica slate with tin and copper veins) is about 900ft. above the 
level of the sea; Springliill gold mine 800ft.; The Union 700ft.; Jansen’s SOOft., and so on. None of these 
heights are ever attained by the flat-topped tableland. 
So far, therefore, from much of the auriferous formation being covered by it, from its nature and eleva¬ 
tion, that formation is far more likely to crop out above it. From what has been said it appears that the 
term “ desert sandstone” is a misnomer. Whether the formation is the same as that which was described under 
that name by Mr. Daintree in Queensland is very doubtful. There are here three kinds of rock. (1) A 
red saudstone composed almost entirely of rounded grains of sand and ferric oxide. The appearance of these 
grains and the stratification of the rock show a desert origin such as blown sands present. (2) Magnesite 
and silicate, and ferro silicate of magnesia; this rock is pure white and yellow or mottled and fiery red. 
These rocks I believe to be derived from the decomposition of fine volcanic ash, containing much olivine or 
otherwise rich in magnesia. South of the Edith river there is a large volcanic area with high basaltic hills 
and much vesicular lava, all rich in olivine. When these volcanoes were in activity (in miocene times), the 
fine dust from the ashes covered a large area. Thus we find these flat-topped cliffs of magnesite lying on 
granite rocks on slates (Mount Shoobridge) and sandstone. (3) The third formation, included under the 
name of “ desert sandstone,” is a fluviatile conglomerate. It is onlyfound on the hanks of streams. It is an 
extremely hard sandstone horizontally stratified and cross-bedded with the finer laminations marked by black 
specular iron. It contains much rounded and watenvorn quartz gravel from the size of a small pebble to 
that of a man’s head. This formation is much broken into immense boulders aiid rocks of most fantastic 
shape. It is very hard, hut being full of cracks and fissures weathers easily and gives rises to a surprisingly 
rough country, almost inaccessible to explorers. It is composed of sandbanks and river boulders, which 
have hardened since the rivers cut through them. Like the banks of the rivers of the present day, they rise 
occasionally 100ft. to 300ft. above the bed, and extend two or three miles on cither side. Mount Douglas is 
an instance of this formation, and in the ranges on the upper Katherine river it is developed to a large 
extent. 
The. above description of the tablelands and other formation will help much to understand the physical 
structure of the Northern Territory, which is *as follows :—The coast is very low and flat, and rises by a 
gentle incline at the rate of about 5ft. a mile ; but there are low ridges of quartzite t slate, and sandstone 
rising almost from the sea-level to a height of 50ft. or more, gradually increasing to 100ft. They run north 
and south, that is generally speaking, with a general trend to the eastward. As they are traced to the south, 
from these ridges small creeks and tributaries take their rise, and descend towards the main valleys, in 
which there are permanent waters. 
The following heights and distances will give a better idea than any descriptionThe Elizabeth, 
distance from Palmerston 25 miles 15 chains, height above sea 52*56ft.; the Berry, distance 35 miles 
70 chains, height 76*84ft.; the Darwin, distance 43 miles 45 chains, height 93ft.; the Finniss, distance 
54 miles 50 chains, height 184it.; the Stapleton, distance 69 miles 64 chains, height 236*50ft.; Peter’s 
creek, distance 74 miles 40 chains, height 188ft.: the Adelaide, distance 76 miles 50 chains, height 183ft.; 
Burrell’s creek, distance 80 miles 12 chains, height 177’o0ft.; Calder’s creek, distance 88 miles 36 chains, 
height 199ft.; Bridge creek, distance 94 miles 59 chains, height 322‘50ft.; the Howley, distance 99 miles, 
height 
