15 
esult in the discovery of a profitable oil-field we shall soon find out sufficient with regard to the 
conditions which exist underground in that field as to throw light upon many areas now partly 
cloaked and hidden under surface coverings such as exist to the north of Tewantin, and wild-catting 
can be directed upon more or less scientific lines. 
Map showing position of Laguna Beach Boreholes, with Geologic and Physiographic Control, and 
with additions by Dr. Wade. Based on Mr. Lionel C. Ball s Sketch Map. 
IV. WOLSTON. 
A. Geology. 
About 13 miles to the S.S.W. of Brisbane a comparatively small outlier of Tertiary sands 
and clays forms the capping of a hill some 90 feet above sea level immediately to the eastward 
of Wolston Station, on the Brisbane Ipswich railway line. Pale-yellow sandy clays or shales, 
in flat lying beds, under a cover of loose sand, are exposed, and these beds contain many plant 
remains in places — casts of leaves resembling those of present day eucalypts are numerous, and 
we were fortunate in finding the fruit of some coniferous tree also. Although such forms are 
abundant in these beds no free carbonaceous matter was observable. What part of the Tertiary 
period these beds represent is at present unknown, but they are probably very late Tertiary 
deposits! To the westward of the railway line the Darra Cement Company has opened a quarry 
in a thick deposit of fine purple shales which are sometimes carbonaceous. The tram-line to the 
quarry runs through a cutting, the quarry opening into a kind of amphitheatre surrounded by 
walls of shale at the south end of the cutting. The cutting exposes about 12 feet of coarse, 
argillaceous, and rather soft sandstones overlain by a few feet of dark, weathered shales, which 
are on the same horizon as those quarried, though here they form the surface. The sandstones 
in the cutting are practically horizontal, though the line of junction between them and the overlying 
shales is very irregular, being in the form of crests and troughs, which look at first like a senes of 
small symmetrical folds. On examining the junction more closely I believe that the irregularities 
observed are due to erosion, and that the shales here rest upon the eroded surface of the sandstones, 
though the unconformity may be only local. At the quarry end of the cutting the sandstones 
disappear abruptly, and the shales dip off sharply to the S.E. This is due to a fault which crosses 
the cutting at this point throwing down the beds to the S.E. In the quarry 70 feet of shales are 
being worked, and no sandstones are exposed. These shales pass under the sandy shales of 
Tertiary age which form the crest of the hill, and lie in horizontal beds so that a distinct 
unconformity is present between the shales of the quarry and the Tertiary shales above. A bore 
