3 
height 250*50ft.; Yam creek, distance 111 miles 69 chains, height 328ft.; the Margaret, distance 114 miles, 
height 340ft.; Foelsche’s creek, distance 122 miles 66 chains, height 318ft.; the McKinlay, distance 
124 miles 68 chains, height 304ft.; SnaddeiTs creek, distance 131 miles 10 chains, height 404*5*0ft.; Lady 
Alice creek, distance 135 miles, height 484ft.; Pine creek, distance 145 miles 79 chains, height 657ft. 
The distances are by the railway line, and the heights above low-water sea-level at the railway crossings of 
the various streams. 
It will be seen that the heights begin to increase rapidly from the ninety-fifth mile, and continue to Pine 
creek ; so that, though the average rise is about 5ft. per mile, it is less than 3ft. per mile for the first 100 
miles, and more than 6ft. per mile for the next fifty miles. This is owing to the commencement of ranges 
which are connected with most of the mineral country in the Territory. These ranges are a series of parallel 
ridges, having a south-south-easterly trend, and rising to a height of from 200ft. to 600ft. in height above the 
plains, though the latter height is exceptional. This mountainous area is about twenty miles in width, and from 
cast to west; and 40 in length, from north to south. In it are contained the sources of most of the small 
tributaries of the Adelaide and Mary, which are rivers with a north and south direction. The Adelaide may 
be said to take its rise m tlie midst of this chain, and the Mary to the eastward and southward. The ridges 
and ranges are separated in their northern portions by somewhat wide alluvial fiats or valleys ; but to the 
south-east the ranges are closer together, higher, and more abrupt, besides being exceedingly stony and 
barren. Thus the country south-east from Mount Wells, as far as the Mary river, is exceedingly rugged, 
and many of the ranges and valleys almost inaccessible. The most closely-metalled road would not be 
more deeply and thickly covered with stones than these valleys and ranges. 
Several long and high spurs (500ft. above the plain) are continued to the eastward into the valley of the 
Mary river, but at about 100 miles from Southport the ranges decline to the level of the plain. At the 
sources of the Mary the river takes its rise amid fiat-topped cliffs of the most picturesque description. The 
view along the stony white gorges has few parallels in Australia. The vallcy r of the river is hemmed in by 
straight cliffs or castellated outliers, some 150ft. or 200ft. high. There is often a slope or talus at the 
bottom, but they are only accessible in a few places. Put the valley is for the most part fertile, and shaded 
by fine giaceful palm tices ; springs bubble out from the shady' thickets at the foot of the cliffs, giving rise 
to streams many feet wide and deep at a short distance from the sources. The valley is strewn to a 
bewildering extent with hugh boulders and masses of rock, which have fallen down from above, because the 
magnesite is very brittle, with a foundation of loose and friable sandstone. Thus no very long time would be 
required tor the springs to crumble and break away the edge of the tableland, or scoop away the valley’s as 
we see them now. These springs, therefore, 1 believe to be the origin of the cliffs and gorges at the heads, 
not only ot the Mary, but of the west and south Alligator rivers, and many besides. The magnesite and 
sandstone strata arc very permeable to water. The heavy' rainfall of the wet season easily drains through 
the strata, and bubbles out at the base where it has weathered and broken away the stone into abrupt 
precipitous and fortress-like hills. 
visited this area. It is evident that it cannot be either important or extensive as a mountain region, as from 
it no stream of any magnitude takes its rise. 
At the Daly rhei we have an outcrop of the metalliferous country with copper mines of unusual 
richness. ±o the south of Pine creek there is a change in the features of the country. Hitherto all the 
drainage is o t ic north, and the sources of the waters are the high lands of tlie metalliferous ranges and tlie 
springs a le oot of the tableland; but about 150 miles from Palmerston (railway distances) a watershed is 
crossc n lg ler than 800ft. above low-water sea level. Beyond this point the streams have a southern 
TtSv i Ct ° n * Un \ l1 tllc Katherine r } ycv is reached, whose bed is about 100ft. above the Mary. 
^ i « i 1S ai £ c r ! AC1 bas a north-west direction, and enters the sea as the Daly river. Thus there is 
? 'T C +0fl ® “ et m °J lIlt " un system, comprising the ranges in which the principal miiies arc found. It is an 
1S ? tl c JS "V lose culminating points are Mount Wells on the north, and the country between the Union 
1 y / 1VC , r 01 \ the south * 11 is cut off to the north by the river Finniss, which has a gene- 
above the sea CS Cr ^ trcn( ’ au( ^ whose coast outlet is unknown. No part of the ranges seems to be over 1,000ft. 
GEOLOGY. 
^e geology of the Northern Territory is of a simple kind. The formations are few in 
ml il or T !. Cr< l are no an d the exposed sections are numerous and clear. The most conspicuous, as 
ctroti6r»ot* S common, is mica slate. It is not crystalline, and therefore I do not call it metamorphic. 
* ‘ 0 1 ? u ls frequently perpendicular, but it is inclined at almost every angle. It is jointed into so 
1U /I‘tin's n i . lac ^ mc . t ia ^ 1 t frhs to small angular pieces when quarried. This has been from pressure, 
? n • Li • j 11 , ) vlt 1 *he way r in which the strata are crumpled and folded, makes it probable that we 
Mother bv lof 010 }^ 1011 1 senes an ticlinal and synclinal folds, as if tlie horizontal strata were crushed 
k ; • • er 'i P rcs sure. Nearly all the upper curves have been subsequently' removed by denudation. 
\ *rp, n P a f s highly ferruginous, and also contains large portions of magnesia, occasionally chlorite 
anl o nnlv it 1 ° * attei 18 ver y common in the mineral form of muscovite. Near mineral lodes, and near 
these oniy, it becomes exceedingly large and abundant. At Talc Head, Port Darwin, the brilliant show of 
m ! ca i > r occurs marks the occurrence of five or six mineral lodes ; also at SnaddeiTs creek, McKinlay 
nunc, * i ount > ho oh ridge. The whole of this formation is paleozoic, and probably, from its mineral 
character, ot the same age as the auriferous slates and schists of Victoria, New South Wales, &c. In those 
colonies i is ca c lower Silurian,” but, in justice to Professor Sedgwick, should he named “ upper Cam¬ 
brian, 01 ^ as . Proposed as a compromise) “ Ordoccian.” There are no fossils to verify this identification. 
I lan irnp ‘Smns are certainly found in the slates at Pine creek, but they cannot he identified as yet; but 
the whole c laraeter of the formation is such as to leave little doubt on the mind of the geologist as to the 
identity in age with the auriferous deposits, elsewhere. 
Di/hcs. n c\ery part of these deposits there are dykes, mineral lodes, and faults. Near Port Darwin 
camp there lias been a considerable overflow of ancient lava, which now consists of a few hills of diorite, a 
volcanic lock or deep blackish-green color and waxy lustre. It consists of crystals of hornblende, mixed with 
No. 122. ’ fel8 P ar ’ 
