62 The Geology of the Portland Promontory, 



of these gulfs stretched from near Adelaide to near Geelong, 

 and occupied a great part of the valley of the Lower Murray. 

 The Grampians and the Otway Ranges were islands in this 

 tertiary sea. Miocene marine beds are exposed in the banks 

 of the Murray at the north-west bend, and in the cliffs of 

 the south coast, in patches from the head of the Australian 

 Bight to Western Port, and a snow-white horizontal stratum 

 of that formation is visible in the craters of some of the 

 volcanoes which stud the centre of the region. These 

 miocene beds rest unconformably upon mezozoic rocks at 

 Cape Otway ; upon paleozoic rocks in South Australia ; and 

 upon both of these formations at different points around the 

 Grampians. They are nearly everywhere covered by beds 

 of a more recent age, and at Portland, the miocene rock 

 forms the base-course of the cliffs. 



The area having been covered with marine deposits, was 

 then raised sufficiently to expose them to view, and these, 

 with others of seolian or volcanic origin, which are super- 

 imposed, will form the subjects of this sketch. 



II. — The Portland Promontory. 



In this locality the undermentioned formations are 

 exposed, but I would remark, that no single section any- 

 where contains all the members : 



Recent. — The sand dunes of the coast ; the marine sands 

 and clays of Narrawong Bay; the marine shell bed of Nelson; 

 the latest lava flows of the Bridgewater volcano. 



Pleistocene. — The false bedded or seolian limestone ; the 

 lower lava flows of Bridgewater. 



Pliocene. — The lava flows of Nelson, and the lowest flows, 

 with the bedded volcanic ash, of Bridgewater. 



Upper Miocene or Upper Murravian. — The oyster bed 

 of Whaler's Bluff; the lava flows of Portland Bay. 



Loiver Miocene or Lower Murravian. — The foraminiferous 

 limestone, or chalk with flints, of Portland Bay. 



III. — The Miocene Formations. 



The foraminiferous limestone, or chalk with flints. This 

 rock is a conspicuous feature in the cliffs at Portland. The 



