29 
'Where it is capped by basaltic rochs, probably of Tertiary age. Beneath the Desert Sand- 
stone lie the metainorphie auriferous rocks of the Gilbert and Etheridge Gold Eields.^ 
According to a geological map of the Gilbert, published by Daiutree in 18d9, 
the country near the junction of the Robertson with the Gilbert is composed of “ slates, 
shales, &e.,” of Lower Silurian age, skirting west-north-west. Eegarding the age of 
the rocks in question, I am not aware that there is any direct evidence beyond their 
general lithological resemblance to Victorian Lower Silurian rocks. The upper 
waters of the Eobertson and heads of the Gilbert are mapped as “ metamorphic-miea 
schists” striking west-south-west. These aud the “ slates, shales, &c., are penetrated 
hy numerous dykes of “elvauite, diorlte, hornblende rocks, &c., and it is noted that 
where these elvanites penetrate slates, payable gold is usually obtained. 
The geological characteristics of the Woolgar Gold Field are similar to those of 
the Gilbert. 
The output of the Gilbert is impossible to estimate, as the returns have been 
. *^pelessly mixed up with those of the Etheridge. In 1877 the IVarden reported that 
in the years 1869-1872 the field “ gave employment to a large number of European and 
Chinese miners, but from a variety of reasons it has been entirely abandoned for 
Upwards of three years, but it is again showing signs of renewed activity.” 
In 1878 there was a considerable accession to the population engaged in alluvial 
working, and prejjarations were being made to re-open abandoned reefs. In 1879 the 
earnings of ,500 Chinese were estimated at a minimum of 7,000 oz. of gold. In the 
sanae year the Gilberbon Gold-mining Company crushed 420 tons of stone for a yield 
of 142 oz. 15 dwt. In 1880 the alluvial diggings were estimated to have yielded 
6;260 oz. In the Warden’s reports after 1880 no separate estimate is made. In 188o 
^ e Warden reported that the Mount Hogan and Twenty-mile Eeefs had crushed 
aring the year 162 tons for 365 oz. of gold. 
In 1887, 450 tons of stone were crushed at Mount Hogan, for a yield of 1,030 oz. 
^ gold, and the population of Gilberton had dwindled to two Europeans. In 1888 the 
ount Hogan machine crushed 1,112 tons for 1,958 oz. For 1889 I am unable to 
give the yield of Mount Hogan, but the Gilberton machine is reported by the Warden 
to have crushed 207 tons, the crushing giving over 1^ oz. to the ton. In 1890, a 10-head 
attery was fully em ployed at Mount Hogan during the whole of the year, and 1,159 
19 dwt. 3 gr. of gold were sold to the Charters Towers banks. At Gilberton 
ittle crushing had been done during the year, but the Charters Towers AVarden reports 
98 oz. 19 dwt. 18 gr. of Gilberton gold purchased by the banks. 
In the ease of the Woolgar, the returns up to 1882 are to some extent mixed up 
with those of the Etheridge, but, so far as they can be separated, the following are taken 
rom the Warden’s books : — 
Yielo or WooLOAB Gold Yield. 
1880 
1881 ... 
1882* 
1883 .. 
1884 ... 
1885 .. 
1880. 
1887 . 
Tear. 
Tons of Stone 
Ci’Aished. 
Yield of Gold. 
Alluvial Gold. 
Total Gold. 
Oz. 
Oz. 
Oz. 
2,500 
2,500 
500 
500 
1,200 
2,400 
200 
i'ooo 
1 ,734 
1,970 
350 
2,320 
5,000 
3,940 
3,940 
2,819 
2,079 
350 
2,429 
694 
709 
709 
11,453 
11,104 
3,900 
15,004 
* Returns included in those of the Etheridge. 
