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was gradually choked up by the deposition of sinter till it became insufficient for the 
passage of the water. The water would then have to find other outlets ; though it is 
quite possible that a much greater volume of water would overflow if the deposit of 
sinter were removed either violently by a “ convulsion” or by artificial means. 
Assuming (as we may with safety) that the “ bed-rock ” on which the sinter 
mound is built up is not ten feet beneath the surface of the surrounding alluvium, we 
have a cone of known dimensions, and could roughly estimate the time required for the 
formation of the cone, kuow'iug as we now' do, from Mr Mar’s Analysis, the amount of 
lime and other salts held in solution by the w'ater, and the amount of w’aler discharged by 
the wells, if observations were carefully made to show the amount of solid matter held 
in solution by the water escaping beyond the limits of the mound. Here again, 
however, we should have to assume that the discharge of water was always the same 
as now, whereas it is probably diminishing, so that w'e should get as a result only a 
minimum time. 
It now remains to consider the evidence bearing on the geological age of the 
Springs. 
In a section from the Etheridge to the Eiuasleigh, taken on the level of the two 
rivers (both about 1 ,200 feet above the sea), mica-schists, gneisses, and granites alone 
would be met with. The mica-schists probably represent sedimentary rocks of 
pre-Devonian age, although I am not aware of any direct evidence to that effect ; and 
the gneisses and granites, metamorphosed rocks of like origin and age. The granite 
largely predominates along the supposed line of section. But above the level of the 
two rivers, the Newcastle Range has been built up, from an elevation of 1,920 feet at 
its base to 2,240 feet near its summit, of a coarse angular volcanic agglomerate. On 
this rests a cake of Desert Sandstone (Upper Cretaceous), perhaps a hundred feet in 
thickness. A strictly parallel section is seen on crossing the Newcastle Range by the 
Townsville and Georgetown Road twenty-five miles to the south. 
Large sheets of basalt occupy the bed of the Eiuasleigh and surrounding 
country w'here the river is crossed by the Townsville and Georgetown Road, and, lower 
down the valley, basaltic coultes are found overlying the older alluvial deposits, having 
been poured down the valley over the bed of the river, which at length cut through or 
found its way past the edge of the basalt. Similar fragments of basaltic coulees, it may 
be mentioned, occupy portions of the valleys of Surprise Creek and the Lynd River, on 
the road from Georgetown to Herberton. 
It was after the denudation of the Desert Sandstone (Upper Cretaceous) and sub- 
jacent rocks had been carried on by the Einasleigh to the depth of a thousand feet that 
the lava-form basalts burst out and flowed down the valley. Probably no inconsiderable 
portion of Tertiary time W'as occupied by this stupendous amount of denudation ; and 
it is more than probable that the volcanic forces which produced the outbursts of 
basalt may still, though diminishing, possess sufficient vitality to give rise to thermal 
springs. j i. • 
In all likelihood, the Einasleigh Springs broke out in the bed of the river 
immediately after the denudation of the basalt — in the bed of the river by preference, 
because there the pressure of superincumbent rock offered the least resistance. The 
building of the sinter-mound would keep pace with the formation of the alluvial terrace 
when the river subsequently altered its course. In modern times the sinter is probably 
overlapping the alluvium. -i j; 
Innot Creek Hot Springs . — These Springs are about twenty-eight miles from 
Herberton, a coach running once a week. A hotel has been built for the accommodation 
of visitors. 
