526 
The beds beneath are of white gritty sandstone with a few quartz pebbles, which 
have yielded several species of Pelecypoda, &c. 
The upper level in the “ True Blue No. 2 South” Claim shows that the sandstone 
is locally faulted against the granite as in the section (Plate 45, fig. 3). 
A series of shafts sunk to the south-east of the hill in search of the True Blue 
Reef, eomineneing below the level of the lowest bed of sandstone seen on the hill, shows 
that a thickne.ss of from thirty to sixty feet feet of white sand rarely consolidated to 
sandi'fone, underlies the strata seen on the summit of the hill, and rests on granite. 
But for the sections laid bare by these shafts the heavy sandy country south and east 
of the True Blue Hill, and connecting it with De Vis Hill to the north-east, would 
certainly be taken as mere debris washed from the hill. Some of the Southern areas 
therefore, already described as covered with sandy “ ddbris of the Desert Sandstone 
tablelands,” may represent the formation actually ia situ. 
By the Railway Survey Croydon is three hundred and sixty-one feet above the 
sea-level, just on the edge of the sandy country. The base of the Desert Sandstone, 
therefore, has come down from 2,240 feet at the heads of the Percy, to three hundred 
and sixty feet at Croydon. 
From a few miles norili of Croydon to Normanton,the road passes over a dreary, 
expanse of low, level, sandy country, which falls indeed towards Normanton, although 
the grade is too gentle to be detected by the eye. In all probability the greater part of 
this district is covered by Desert Sandst )ne, although it is devoid of sections throwing 
any direct light on its structure, or at least none were to bo seen when I travelled over 
it in December, 1889, the whole country being almost one sheet of w.iter. The precisely 
similar country to the east of Normanton is described by Daintree* as covered, over 
two degree.s of latitude, from the Norman to the Hilbert, by Desert Sandstone. 
In a Report by Mr. A. Hibb Maitland, ” On the Heological Features of the 
Environs of Normanton,” f the Desert Sandstone Rocks of that neighbourhood are 
thus described : — • 
“ Apart from the superficial deposits, the beds of the Desert Sandstone Series 
occupy by far the greater portion of the surface of the district. In the absence of any 
trustworthy data it is impossible to give any idea of their thickness. A variable 
thickness of concretionary ferruginous sandstone, not unlike a conglomerate in appear- 
ance, forms the upper portion of the series. Beneath this lie clayey sandstones, red, 
brown, and even white in colour, which pass in places into rocks possessing all the 
characters of true clays. In the well-sections seen within the municipal boundary, 
these sandstone.s are associated with clay shales and true clay beds, often lenticular in 
shape and of no great horizontal extent, and which in colour are generally yellowish- 
white. A bore put down in 1885 by the Carpentaria Divisional Board at the junction 
of Thompson and Woodward Streets, within the municipal boundary, shows ‘ironstone 
rock,’ ‘ mild rock,’ sandstone, and clay to a depth of two hundred and twmnty-four feet. 
The height of the surface of the bore is thirty-seven feet above high-water mark. It is 
greatly to be regretted that no samples of the material passed through have been kept, 
more particularly the ‘ vei-y hard rock’ met with when it was decided that boring opera- 
tions should cease. From an examination of the record and from what is actually seen 
in the well-sections, the whole thickness of rocks is provisionally classed with the Desert 
Sandstone. It is, however, probable that what are described as ‘ clays ’ are not all true 
clays, but merely sandstones and shales containing a high percentage of argillaceous matter- 
* General Report upon the Northern District. Brisbane ; bv Authority : 1870. 
t Brisbane : by Authority : 1890. 
