7 
continuity of the strata around Beaudesert, causing considerable zones of contact metamorphism 
in places. Similar conditions exist near Boonah also, although to the north of Boonah, in the 
vicinity of Roadvale, there is a considerable tract of country which seems to be clear of such 
disturbing features. In this district some subsidiary folding is observable in the Walloon Series 
in the western synclinal area. 
C. Petroleum. 
It is a pity that the finely developed central fold, the Overflow anticline, should be developed 
in such an unpromising series as the Bundamba sandstones, otherwise this structural area would 
have been good prospecting ground. Morton, in the paper referred to, adequately sets out good 
reasons against the favorable consideration of the folded area occupied by the Bundamba. A 
thick porous series of this character is hopeless. It is not at all certain that the Ipswich Coal 
Series underlies the Bundamba in this area. There is reason to suppose that it does not. In 
any-event, the Ipswich beds have never been seriously considered as containing petroleum horizons. 
Nothing that has been recorded in the boring and sinking for coal has indicated the possible presence 
of oil, while Morton points out that in the neighbouring Logan and Albert districts the coals of 
Ipswich age have carbon ratios of from 63 to 72, which indicates a degree of metamorphism in 
these beds which is quite unfavorable to the presence of oil accumulations. Since I must refer 
to the question of carbon ratios frequently, a brief statement of the carbon-ratio theory is necessary 
at this point. 
A paper by Fuller* sets forth this hypothesis, which has been developed since White t 
'first suggested it in 1915, more concisely and clearly than I have found elsewhere. The following 
extract has been much quoted : 
In general, it has been found that in the oilfields throughout the world, the occurrence of 70 per cent, fixed carbon 
n pure coal (ash and water eliminated) establishes a dead-line as regards petroleum and natural gas, for although slight 
accumulations of these products may be found outside of this line, no instances of commercial deposits are known. 
With lower carbon ratios oil and gas may be expected, the amount and quality varying with the degree of metamorphism 
as expressed by the percentage of fixed carbon in coals. The comparative promises of the various zones are roughly 
indicated below : — 
Relative Chance of 
Finding Oil. 
Zone of 50-55 carbon ratios . . . . . . . . 100 
Zone of 55-60 carbon ratios .. .. .. ■■ 10 
Zone of 60-65 carbon ratios . . . . . . . . 1 
As a matter of fact the chances above 60 per cent, are probably even less than indicated, there being no known oilfield 
of importance above this ratio, although several small high gravity pools occur near the 60 per cent, line at points in 
the Appalachians. 
While there is still some doubt as to whether this generalization holds good as universally 
as many American geologists believe, and investigation is still desirable in many oilfield areas 
outside of the United States, it has been worked out in its practical application so accurately 
in many of the oilfields of America that it must be accepted by all who are working towards oilfield 
development, even if it be accepted at present with caution. While the prospector must use the 
carbon-ratio hypothesis as a useful guide, he must not be led away from the consideration of all 
other factors, historical, structural, and physical, which may offer themselves for observation 
and study in the area with which he is dealing. 
Apart, therefore, from the absence of any indications of the presence of petroleum in the 
Bundamba Series, and the underlying Ipswich formation, if it be present in this area, other- 
conditions obtain which discourage the belief that oil might possibly be obtained by drilling on 
the Overflow anticline. It is necessary, therefore, to consider the areas on either side of the 
anticline which are occupied by Walloon strata. The only drilling for oil accomplished so far 
has been in the neighbourhood of Beaudesert. This was undertaken on account of the discovery 
of slight showings of oil in a shallow water well 85 feet deep, some 3 miles to the south of the town. 
On visiting this area, I found several shallow water wells, which had been put down by the local 
farmers, and two shallow- wells- one 375 feet deep and the other 160 feet deep- — which had been 
put down on Mr. Dunn's farm with the idea of prospecting for oil. On pumping the water from 
some of these wells a very thin, pale, ir idescent film, of a nature which would indicate the presence 
of a small amount of very light oil. could be noticed on the surface of the water. Analyses of 
waters and sludges from the bores made by Mr. Henderson, the Govermneent. Analyst in Brisbane, 
and quoted by Mr. Ball.J who visited this area on two occasions while drilling was in progress, 
show very small percentages of oil to he present, varying from .0009 per cent, to .013 per cent. 
Mr. Henderson describes the residue as of the nature of mineral grease or wax. A little gas is 
reported to have been present in the 375-ft. borehole. Although the three bores put down on 
Dunn's farm are grouped together in the space of about 1 acre, it is worthy of remark that the 
* Fuller, M. L, “ Relation of Oil to Carbon -ratios of Pennsylvania Coals in* North Texas. — Econ. Geo)., vol. XIV., No. 7, 1919, pp. 536-542. Bee 
aDo “ Carbon -ratios in Carboniferous Coals of Oklahoma and theirTrelation to Petroleum.** -Eeon.*Treol., r vol. XV.. No. 3. 1920, pp. 225-235 
t White, David. “ Some Relations in Origin between Coal and Petroleum.” — .Tour. Wash. Acad. Be., vol. V., No. 6, 1915, pp. 189 212. 
+ Bail, Lionel C. Report on Oil Prospecting at Beaudesert.- Q.G.M.J., vol. XXV., No, 293, 15th Oct., 1924, pp. 362-365. 
