458 PROCEEDINGS OF SECTION ©. 
In addition to the grading by lines, &c., the proposal accepted by 
the Congress that each system should be represented by a corres- 
ponding capital letter, is essential to render the scheme complete. 
Mr. Selwyn, formerly Government Geologist in Victoria, and now 
of Canada, adopted a system on his maps which at once conveyed 
the sequence of underlaying strata by printing letters on each 
formation, thus for example V. 1.3, on T.P. 1.3, on 8. 1.2, signifying 
Volcanic 1 and 3, on Tertiary Pliocene 1 and 3, on Silurian | and 2. 
The system of colouring referred to above, of course, could only 
be done by lithographic printing. The practice of colouring 
geological maps by hand for publication should, I consider, be 
abandoned as being too indefinite, liable to fade, and the darker 
shades so opaque as to destroy all trace of the topographical 
features, whereas, in lithographic printing, the darkest shades are 
always transparent, and if colours of the best quality be used 
there is little chance of their fading. Large portions of some of 
the maps of the geological survey of Great Britain and Ireland 
are covered with such dark opaque colours as to entirely obliterate 
the beautiful topographical work of the geodetic sheets. In 
conclusion, I will give an extract from the address of the Presi- 
dent of the Geological Society of London :—‘ The fact is, that 
the distinctness of colours adjacent to each other is an essential 
requirement of any efficient system, though but few of those who 
have treated of map colouration with the Congress have referred 
to this important point. It must be remembered that all hues in 
contact should remain sufticiently distinct after a certain amount 
of fading from exposure, and that all should be easily distinguished 
by artificial light.” 
13.—ON THE THERMAL SPRINGS OF THE EINAS- 
LEIGH RIVER, QUEENSLAND. 
By Ropert L. Jack, F.G.S., F.R.G.S., Government Geologist 
for Queensland. 
| Adstract. | 
From five shallow wells, streams of water, estimated at 589 
square inches section, issue at a temperature approaching the 
boiling point, and accompanied by gas-bubbles. The water has 
deposited a mound of travertin 15 feet in height and 260 yards in 
circumference. Themound is terraced with successive basins or cups. 
After the denudation of the desert sandstone (Upper Creta- 
ceous) and subjacent rocks in the valley of the Einasleigh to the 
depth of 1000 feet, lava-form basalts flowed down the valley. 
After the basait had been itself denuded till mere fragments. 
were left, the thermal springs burst out—probably, therefore, 
well on in Tertiary times. 
