166 Proceedings of the Royal Society of Victoria. 



It is more of the character of the necks in the hill area, and con- 

 sists largely of basalt,jWith no tuffs. Mr. Ferguson, who has 

 examined it carefully, tells me that he regards some of the material 

 as an agglomerate, so perhaps it may be included among the series 

 characteristic of the plains area. These will be dealt with in. the 

 official reports of the surveys of the areas, so no further descrip- 

 tion of them will be given here, save to mention that Watson's 

 tuff" occurrence has the character of a fissure neck. It is a long, 

 narrow strip of laterite and lapillaceous tuff", traceable almost 

 continuously for a length of nearly 40 chains, with an average 

 width of about 2|^ chains. 



All of these are probably volcanic necks, and not remnants 

 of extensive beds of tuff" and flows of basalt. There are, probably, 

 numerous other occurrences of tuffs and basalt distributed over 

 the plains, but hidden from sight by the thin covering of sedi- 

 ments present. 



Age of the Volcanic Necks. 



Speaking in general terms, the age of the volcanic activity, of 

 which the necks furnish evidence, can be set down with some 

 degree of certainty. That it is post-Jurassic, of course, admits 

 of no question. There seems almost conclusive correlative evidence 

 that it was contemporaneous with the " Older Basalt " of the 

 Mornington Peninsula and Western Port region. There, in sea 

 cliffs along AVestern Port, the Cape Sclianck coast, and at San 

 Remo, basalt and associated tuffs can be clearly seen. 



Resting on this basalt at Flinders is a small isolated patch of 

 Bryozoan limestone^ of Eocene age, so clearly the basalt there 

 belongs to the Eocene or pre-Eocene period. 



In various localities, such as at Berwick, Bacchus Marsh, 

 Dargo High Plains, etc., leaf-bearing clays of probably Eocene 

 age, underlie these basalts. There seems, therefore, no strong 

 reason to doubt that tiie necks belong to the Eocene period. 



1 Pritcharcl, G. B.: The Geology of Flinders, "The Victorian Naturalist," February, 

 1903 ; Kitson, A. E.: Report on the Bryozoan Limestone at Flinders, " Records Geol. Sur. 

 Vic," vol. i., part i., 1902. 



