12 
A typical cliff section taken near the edge of the beach near the southern group of boreholes 
reveals the presence of a bed which must be described. The section is — 
White and red ferruginous sands, false-bedded, with dirt beds, i.e., 
sand and humus 
Oil shale, containing lignitic matter and little altered wood 
Fine sticky clay 
Fine white soft sands 
200 feet 
3 feet 
2 inches 
Several feet ex- 
posed 
An excellent description of the oil shale has been given bv .Mr. L. C. Ball. Deputy Chief 
Government Geologist, who has visited this area on several occasions. Mr. Ball has not only made 
original contributions to the geology of the area, but has carefully recorded the results obtained 
by drilling, and stated his conclusions as to the prospects of finding oil. The following extract 
is from one of Mr. Ball's reports : — * 
A lenticular bed of oil shale is exposed at the base of the ffa near the earlier boreholes, and another smaller 
lens shows in the face of the cliff, 50 feet above high-water mark, about 6 miles down the beach towards Tewantin ; 
hut neither has been shown to extend for more than a few chains laterally. The latter is 18 inches to 2 feet thick, and 
consists of pale-buff to dark-brown hardened silt with coaly streaks. The former has been proved to a depth of 5 feet, 
though only the upper part now is uncovered. The material exposed has a dark-brown to black fine-grained clayey 
matrix, it is .soft and has a greasy streak, and on exposure to the atmosphere bleaches slightly while shrinking and 
cracking in all directions owing to dehydration. A sample collected by me in December last contained 8 per cent, 
bitumen, and on destructive distillation yielded 19 gallons of dark-brown liquid per ton, but it was not certified that 
the shale contained any free oil. The report of the Government Analyst is appended : — 
Proximate analysis — 
Moisture. 7.6 per cent. : volatile matter. 40.3 per cent. ; fixed carbon, 17.3 per cent. ; and ash, 34.8 
per cent. 
Extraction by solvents — 
Bitumen, soluble in chloroform. 8.2 per cent., of which 4.7 per c-ent. is soluble in petrol. 
Destructive distillation — - 
A dark-brown liquid, equivalent to 19 gall, per ton. Nitrogen equivalent to 0.38 per cent, of ammonia 
(F.E.C.). 
Several fragments of rotten, but not carbonized, wood were found embedded in the oil 
shale at the 5-ft. hole ; and concerning specimens collected bv me, Mr. V. D. Francis, Assistant 
Botanist at the Botanic Museum, Brisbane, writes : — 
From the extremely eccentric structure of the specimen when examined in cross section it is evidently a part 
of a buttressed root. Some microscopic examinations of the material were made, and I have been able to identify 
it as part of the buttressed root of Ceriops Candolleana. This is a mangrove which is found on muddy shores of the 
sea in Queensland and tropical Asia. The buttresses are seen in this species when it is only about 4 feet in height, and 
•they form a conspicuous feature in the facies of the tree. 
Mr. Ball considers that the oil shales represent muds deposited in estuarine waters. The 
beds are not only lenticular, but the lenses are distinctly concavo-convex, the concave side being 
above, i.e., they are saucer -like in shape. This confirms Mr. Ball's opinion. They were probably 
deposited in the swampy estuary of a gully running between transverse sand ridges to the sea, 
which subsequently became choked and filled by the movement of the sand. Alternatively, they 
may be found, when examined in more detail, to represent one of the old swampy areas which 
still exist behind the sand ridges fringing the coast, that has been brought near to the shore line 
by depression, filled in by the coastal dune sand, and subsequently cut through and exposed by the 
action of the sea. I am told that good samples of this oil shale have yielded up to 35 gallons 
of oil to the ton on distillation, which must be regarded as a good result. Although the bed has 
suffered comparatively little compression and alteration, and still holds a very high percentage 
of moisture, it shows many of the characteristics of a true oil shale which is remarkable consdering, 
its comparatively recent origin. It demonstrates beautifully the mode of origin of oil ishales 
and is a type of deposit which has not often been noted in Recent or Post-Tertiarv sediments. 
All around this area of sand dunes and Post-Tertiary deposits on the landward side Ball 
has shown that the beds outcropping at the surface consist of sandstones, grits, conglomerates, 
and shales of Triassic age, a northern development of the Ipswich formation. The sandstones 
are sometimes argillaceous, and the shales carbonaceous, while seams of coal have also been found 
in them. These beds are penetrated by igneous intrusions in places, and have undergone 
considerable metamorphism, so that they are often considerably indurated. The beds have been 
considerably disturbed by folding, and dips up to 30° have been noted. Similar strata have 
been proved to underlie the Post-Tertiary sands in the deeper bores along the beach at a depth of 
about 200 feet. These also contain thin seams of coal between the depths of 400 feet and 657 feet. 
Fragments of fossil plants obtained by Mr. Ball from a shale bed at 269 feet in borehole Xo. 5 have 
* Ball, Lionel 0. “ Report on Oil Prospecting near Tewantin." — Q.O.M.J., vol, XXV.. Xo. 293, 15th Oct., 1924. pp. 355-356. 
