52 GEOLOGY OF LOWER MESOZOIC ROCKS OF QUEENSLAND, 



(e) Extent and Distrihiition.—ii.) 7'he Ipswich Snnes. — The 

 Ipswich Series is of comparatively limited extent, and has a 

 thickness, in the type-district, of about 2,000 to 2,500 feet, as 

 estimated by Mr. W. E. Cameron. Its best development is in 

 the Ipswich district, where the strata have been studied in detail 

 by Mr. Cameron.* 



North-west of the town of Ipswich, the north-western end of 

 the Ipswich Series is hidden by Cainozoic rocks. ^Mapping in 

 this portion of the area has not been carried out in detail, but 

 apparently the Ipswich Series cuts out between the Bundamba 

 Series and Brisbane Schists (as shown in Plate ii.), and it is not 

 known to outcrop further in this direction. It is, of course, pos- 

 sible that this series extends some distance north under the 

 Walloon Series, but one might expect, in this case, to find some 

 indication of its presence by outcrops between the outcrops of 

 the Walloon Series and the older rocks to the east. 



From Ipswich, the Ipswich Series extends in a general easterly 

 direction to Oxley, where it disappears beneath overlying Caino- 

 zoic rocks, as shown on the most recent maps prepared b\' iMr. 

 Cameron. It reappears along a line running approximately 

 N.30°W.-S.30''E through Brisbane, and is succeeded to the east 

 by a line of schists of Pala?ozoic age. This belt of Palaeozoic 

 rock is not very wide here, and, on the eastern side of it, the 

 Ipswich Series reappears. Between Mt. Cotton and Mt. Petrie, 

 the two belts of Ipswich Series are in direct connection, as also 

 are they between Mt. Petrie and White's Hill 



Still going to the east, the Ipswich Series again disappears 

 under the overlying Bundamba sandstone along a line running 

 in a N.30°W. direction through Hemmant, and reappears on the 

 other side of a syncline at various points on the coast south of 

 the Brisbane River. The axis of this syncline is in a direction 

 N.30°W.-S.30°E. 



The whole of the Ipswich Series so far described skirts the 

 southern extremity of an extensive occurrence of the schists 

 known as the Brisbane Schists, whose age is uncertain, and can 

 only be stated definitely as Pre-Mesozoic. 



* Queensland Geol. Surv., Publications Nos.147, 204, 



