200 president's address — section c. 



x^eference of a basalt to the older or newer series is frequently based 

 only on conjecture or analogy. The Geological Survey has experienced 

 and had to face this difficulty in colouring the Geological Map of 

 Victoria. In the map of 1902, on the scale of 8 in. to the mile, a few- 

 areas of newer basalt are shown in North and East Gippsland, and 

 three areas of older basalt are shown near Bacchus Marsh, the 

 Moorabool River and the Bellarine Peninsula. With these exceptions 

 a line drawn north and south through Melbourne separates the 

 areas coloured newer basalt to the west from areas coloured older 

 basalt to the east of this assumed line. In the small geological map 

 published in the Settler's Guide in 1905, the only alteration in the 

 rnappmg of the Kainozoic volcanic areas is the alteration of those 

 areas in North and East Gippsland formerly coloured as newer basalt 

 and the reference of them to the older series. 



In this paper the distribution as shown by the Geological Survey 

 in the 1905 map, the latest available, is followed, but I should be 

 unable to give any satisfactory reason for referring many of the areas 

 to one rather than the other series. 



Adopting, however, this method of grouping, a reference to the 

 niap accompanying this paper will show that a number of ai'eas near 

 Melbourne are referred to the older basalts. At Royal Park, 

 Essendon, and Keilor, basaltic rocks occur beneath the Lower 

 Kainozoic fossiliferous sediments (l-')4). Much the same relations 

 obtain near Morning-ton and Flinders. In the valley of the Moorabool 

 River, near Maude, the lower l)asalt is interbedded between two 

 distinct marine limestones, both of which are of L. Kainozoic age. 



At Curlewis, near Geelong, and at Airy's Inlet, older volcanic 

 vents occur (169), and flanking them are agglomerates and tuffs. At" 

 Curlewis a Lower Kainozoic marine polyzoal limestone overlies the 

 older volcanic rock. Near Bacchus Marsh, leaf beds, regarded as of 

 L. Kainozoic age, overlie the older basalt. In all these cases cited the 

 evidence of age is fairly satisfactory since the rocks are overlain by 

 fossiliferous sediments. At Berwick, 27 zniles south-east of Melbourne, 

 a basalt referred to the older series immediately overlies and seals 

 (ip clays containing leaf remains referred by Deane (161) to the L. 

 Kainozoic. 



At an altitude of about 5,000 ft. on the Dare'o and Boo-ono- liig-h 

 plains basalts occur which seal up deep lead gravels containing fossil 

 leaves and fruit which have been referred to the Lower Kainozoic. 

 1)1 these three cases the evidence of age of the basalts is less satis- 

 factory. It is probable but not certain that the basalts were poured out 

 almost contemporaneously with the deposition of the subjacent leaf- 

 bearing deposits. Again, fossil leaves and fruit, even when well 

 preserved, are at the best unsatisfactory remains on which to arrive 

 at the age of a deposit, and a good deal of uncertainty must still 

 attach to the age of the basalts just mentioned. A number of other 

 areas remain, such as the volcanic necks of Anderson's Inlet (165), 

 other areas in South Gippsland from Leongatha to Warragul, Philip 

 and French Islands, and numerous areas in North and East Gippsland, 

 where no upper limit to the age of the occun*ences can be assigned 

 with any certainty. In each case the basalts pierce or overlie rocks 



