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LynS, River. —L couUe of basaltic lava has flowed down the Valley of the Lynd. 
The coulee is two miles in width where it is crossed by the Herberton and G-eorgetown Eoad, 
covering the whole of the district between the Lynd and Fossil Brook. Fossil Brook is 
remarkable as being a strong running stream even in seasons when the Tate, the Lynd, 
and other larger streams in the neighbourhood are dried up. The permanence of streams in 
basaltic country has often been remarked. The basalt of Fossil Brook rests on gneiss rock. 
Rlach Springs.— On the same road, further west, a basaltic couUe, about a mile 
in width, occupies the valley of the creek which takes its rise at the Black Creek. 
Surprise Creeh.—ln the bed of Surprise Creek, and forming the plateau upon 
which the “ Quartz Hill Hotel” (Herherton and Georgetown Eoad) is situated, is a 
highly vesicular basalt with immense geodes coated sometimes with calcite and sometimes 
with silica. The basalt extends about a mile from the left bank of the creek. Mr. 
Maitland has examined thin sections of this rock, and has furnished me with the 
following note ; — 
“ A specimen collected is of a dark greyish-blue colour, and somewhat porous and 
vesicular. Scattered through it are yellowish grains of olivine, which often show a 
beautiful iridescence on fresh fractures. Under the microscope the rock is found to be 
made up of a granular mixture of felspar, augite, and olivine, with a little magnetite. 
The felspar (plagioelase) occurs in long lath-shaped crystals, and is perfectly clear and 
transparent. The crystals (which do not attain any great size) are remarkably free 
from alteration. The augite occurs in crystalline grains, and is usually of a pale brown 
colour, and exhibits faint dichroisin. The olivine, which occurs porphyritically amongst 
the other constituents, has almost always undergone a certain amount of alteration into 
some ferriferous substance ; generally the alteration is seen to commence along the 
external boundaries of the crystals, and to extend gradually inwards along lines of 
weakness. The magnetite, which is more easily detected with a magnet than under a 
microscope, exists as small grains of every conceivable shape. In addition to these 
constituents, there are long, colouidess, acicular crystals of what appear to be apatite. 
A fair quantity of glassy matter is discernible throughout the slice. A rock of this 
character would be classed with the ‘ felspar-basalts.’ ” 
Emasleigh .Riser. —Large sheets of basalt occupy the bed of the Einasleigh 
Eiver and adjacent country w'hcre the river is crossed by the Pentland and Georgetown 
Road, and also the valley of Spring or Lagoon Creek, near Carpentaria Downs Station, 
and the Copperfield Eiver where it is crossed by the same road. Lower down the 
Einasleigh valley basaltic couUes overlie alluvial deposits older than those of the recent 
times, having been poured down the valley over the bed of the river, which at length 
cut through, or found its way through past the edge of the basalt. 
It was after the denudation of the Desert Sandstone of the Newcastle Range, which 
overhangs the left wall of the valley, and subjacent rocks, had been carried on by the 
Einasleigh for at least 1,000 feet that the lava-form basalts burst out and flowed down the 
valley. Near the basalt a thermal spring, described in another chapter, shows that the 
volcanic forces which produced the basalt, though diminishing, still possess some vitality. 
The basalts overlying auriferous drifts on Kroombit Gold Field probably belong 
to the New Volcanic series. Mr. Rands * thus refers to these basalts : — 
“ Small outliers of basalt overlie the Gymjiie Beds on the range dividing the 
Kroombit and Three Moon Creek waters. A patch of basalt occurs about two miles 
north-west of the township [Cania], and a small outlier is seen about three-quarters of a 
mile south of Starlight Gully. The basalt is full of small blebs of olivine. 
*Annual Progress Report of the Geological Survey for 1890. Brisbane : by Authority : 1891, 
2 0 
