BY A. B. WALKOM. 53 



From the Brisbane River, extending north as far as Mary- 

 borough, there is a narrow, coastal belt of Lower Mesozoic rocks. 

 These are, here and there, intruded or overlain by volcanic rocks 

 of Cainozoic age, with which we are not concerned here. The 

 Mesozoic rocks of this coastal belt are gently folded into anti- 

 clines and synclines, the general direction of dip being north- 

 easterly or south-westerly. 



This coastal belt averages about 15 to 20 miles in width. At 

 its southern end, it consists of rocks of the Ipswich Series, repre- 

 senting a continuation of the syncline just mentioned south of 

 the Brisbane Biver. The Bundamba sandstone in this synclinal 

 area does not extend much north of the Brisbane Fviver, and 

 appears to be entirely surrounded on its northern end by the 

 Ipswich beries. The north-eastern side of this syncline, pro- 

 duced northwards, forms the south-western arm of an anticline 

 whose axis passes approximately through the region of the 

 Glasshouse Mountains, in a direction N.SO^W., and whose north- 

 eastern arm dips away towards the north east under the sand- 

 stones of the 'J'oorbul Point-Landsborough district, which pro- 

 bably represent the Bundamba Series. 



This is the last that is seen of the outcn^p of the Ipswich 

 .Series, and their extent under the Bundamba Series to the east 

 and north east cannot be determined. 



The distribution of this Series is indicated generally in Plate ii. 



(ii.) The Bundamba Series. — The Bundamba Series comprises 

 a development of massive sandstones in which there are practi- 

 cally no fossils, the only ones so far recorded being examples of 

 fossil wood. Mr. Cameron estimates the thickness of the Series 

 at between 3,000 and 5,000 feet. 



This Series overlies the Ipswich Series conformably. It ex- 

 tends, roughly, from the Ipswich District eastwards to a little 

 beyond the railway-line between South Brisbane and Kingston, 

 and in a general south-easterly direction past Canungra to the 

 New fcouth Wales border. It is impossible, in this area, to 

 define accurately the limits of the formation, but its existence is 

 beyond doubt. Mr. Dunstan has recently observed it in iSew 

 South Wales, not far from Mt. \N arnini{. 



