586 
“ The hill, 2,475 feet high, to the south-west of the section, is formed, of a series 
of successive sheets of lava. 
“ It is impossible to estimate the thickness of the basalt on the plateau, because 
there are no data available which will enable an idea to be formed as to what was the 
form of the ground before the lavas were poured out ; and, further, there is no record 
of their ever having been penetrated by any excavation. 
“ The age of those basaltic outflows has not yet been definitely fixed. The lavas 
rest in turn upon all the other rocks in the district ; one section, seen near the Yalley of 
Lagoons Station, shows them resting directly upon the .Desert Sandstone Beds. The 
basalts, therefore, are younger than the Upper Cretaceous. 
Mr. Daintree conjectured (presumably on account of their lithological 
similarity) that the lavas to the ‘north of latitude 21° were probably the equivalents 
of the “ Upper Volcanic series ” ’ of Victoria which were referred to Pliocene- 
Tertiary.* 
“Lithological similarity is not to be safely relied upon in determining geological 
age ; still there is strong presumptive evidence that all these basalts have been emitted 
at approximately the same time. 
“These Upper Burdekin lavas are in all probability Tertiary, but as to the 
exact horizon to which they are to be as, signed no evidence has yet been collected.” 
It is impossible, on reading the above account, to avoid suspecting that in the 
above notes Mr. Maitland is describing basaltic outflows of different ages — an older, to 
which the bulk of the basaltic tableland belongs, and a newer, to which may be referred 
the “ puys ” or foci still remaining in a remarkable state of preservation, and in all 
probability the flows of basalt which come down the valleys below the edge of the 
basaltic tableland. One of these comes down the Valley of lleedy Brook, washed on 
either side by its tributaries Kinrara and Ueedy Creeks. This flow is at least twenty-five 
miles in length, and I was informed by the late Mr. Scott, of the Valley of Lagoons, 
that it emanated from a crateriform hill near the head of Kinrara Creek. 
Beds of white pipeclay are occasionally met with between the beds of basalt on 
the tableland. 
On both sides of the range which divides the upper portion of the Herbert Eiver 
on the west from the Johnstone and Barron Rivers on the east, are large plateaux of 
horizontally-bedded basaltic rocks. On the western side the thermal spring of Innot’s 
Creek remains to attest that the volcanic activity has not yet entirely died out. Mr. 
Maitland has furnished the following Notes on a specimen of the basalt from this 
district, after a microscopical examination : — ■ 
“ Specimens collected from the bed of Prior Creek — one of the heads of Mazzlin 
Creek, a tributary of the Barron, at the crossing of the Port Douglas and Herberton 
road, where beds of (marse vesicular basalt alternate with others of much finer grain — • 
were found to be of bluish-gray colour, with small grains of olivine set in a fine-grained 
matrix. Examined under the microscope the rock is found to consist of a fine-grained 
matrix, made up of lath-shaped plagioclase felspar, augite, and magnetite, through which 
large crystalline grains of olivine arc scattered. 
“ The felspars, which form by far the largest portion of the rock, are remarkably 
clear and fresh. Under a high power they are seen to contain glass-inclusions, minute 
needles of apatite (?) and colourless inicroliths of augite. 
“The ferro-magnesian constituent, augite, never occurs porphyritieally, but 
always as a constituent of the ground-mass. Well-defined crystals are absent, the 
Quart. Journ. Geol. Soc., xxviii,, p. 313. 
