CHAPTER XXVI. 
THE TEIAS-JUEA SYSTEM— 
THE IPSWICH EORMATIOH (UPPER TRIAS-JURA) IH THE TYPE DISTRICT-eo)!i'm««?. 
In and near the Town of Ipswich, the strata are tilted at high angles, and are 
accompanied by flows of basalt. I cannot, however, see any clear evidence that the 
tilting of the strata is due to the igneous rocks. On the eontrary, there is every 
appearance of the latter being interbedded with the former, and having been tilted 
simultaneously with them.* On the summit of Limestone Hill, within the Town 
boundary, two bods of limestone are seen, the uppermost being about ton feet thick, 
and resting on thirty feet of grey and reddish shales. Beneath the shales is a thick 
bed of basalt, which, again, rests on a thick bed of limestone. A second mass of basalt 
is seen beneath the lower limestone bed. The liinestones dip at a high angle to the 
north-east. I am inclined to believe that the upper bed of limestone is, so to speak, 
conformably” overlaid by a thick basalt, which, at first dipping with the same high 
angle as the limestones and shales, gradually flattens out eastward, till its base again 
rises to the surface on the left bank of Buudamba Creek. The limestone, as seen at its 
outcrop, is rather the siliceous skeleton of a sandy limestone, and contains frequent 
kernels of chert. It appears to be quite unfossiliferous. It i.s described by Gregory 
as “ tufaceous limestone, containing siliceous concretions.” 
The most important description of the Ipswich Coal Field published up to the 
present date, although it is one of the earliest, is that of Mr. A. C. Gregory.f This 
T^aluable Eeport, which I find it impossible to abridge very much, deals principally 
with the character of the various coal-seams. The following extracts are taken from 
the Eeport : — 
“ Old Mor/f/ill Coal 3 Iine . — The Moggill coal-seam being confined to a small area 
by the river on the east and south, and by a fault on the west, the available coal was 
soon worked out, and the mine has been abandoned for about ten years. It is stated 
that the seam was about six feet thick, but not of a very high class, probably owing to 
its being worked so near the outcrop. 
‘‘Mr. Lyons' Coal Seam . — About one mile to the W.S.W. of the Old Moggill 
Mine, several outcrops of coal are visible, and a shaft has-been sunk seventy feet by 
Mr. Lyons, on Portion 117, and a scam of coal five and a-half feet thick cut at forty-five 
feet. The coal has several thin bands of bituminous shale, but, rejecting the bauds, 
there would bo from three to four feet of good available coal. 
Section taken from the shaft and adjacent outcrops ; — 
Eeet. 
Coarse grit, irregularly stained with iron 
10 
Coarse conglomerate 
8 to 10 
Coarse sandstone 
20 
Hard shales ... 
15 
Coal 
63 
Thin-beddcd sandstones and shales ... 
60 
Coal 
1 
Thick-bedded coarse sandsfones 
over 60 
* See Plate 49, fig. 1. 
t Report on the Coal Deposits of the West Moreton and Darling Downs District. Brisbane : by 
•A-Uthoritvi 1876. 
