CAINOZOIC GEOLOGY OF THE MALLEE AND OTHER 
VICTORIAN BORES. 
By Frederick Chapman, A.L.S., F.R.M.S., Palaeontologist to the 
National Museum, Melbourne. 
1. INTRODUCTION. 
The Tertiary or Cainozoic deposits of Southern Australia have presented 
many problems to the stratigraphical geologist in regard to the true succession 
of the beds and their vertical extent. These matters can only be solved 
satisfactorily by an exhaustive examination of the material brought up from 
various depths at given localities by means of deep boring. The present 
opportunity of studying one of the most extensive series of borings yet made 
in the Victorian Tertiary beds at any locality was therefore hailed with 
satisfaction, when the work of testing for water-bearing strata in the Mallee 
was undertaken by the Agricultural Department of Victoria. 
The collection and preservation of material from each of the bores here 
dealt with was superintended by Mr. A. S. Kenyon, C.E., Engineer State 
Rivers and Water Supply Commission, who, with Mr. J. J. Scarce, the 
foreman in charge of the borings, deserves credit for the care in conserving 
the data regarding depths, without which the results embodied in this report 
would have lost considerable value. 
The ancient geological and geographical features of this area of the Mallee 
district in Tertiary times will be dealt with more fully in Sections 7 and 8 
of this report. Suffice it here to say that the underground geology of this 
part of the country proves the existence in Middle Tertiary times of a great 
gulf of the Southern Ocean, which was bounded on the west by the 
Raiseozoic axis of which the Mount Lofty ranges forms a part, and was 
probably continuous with the Miocene sea of the Mount Gambler 
district. The latter point is clearly borne out by the similarity of 
the fossil faunas of both areas, as shown in this report. This inland 
sea was partially enclosed by an intermittent barrier of metamorphic rocks, 
remnants of which appear at the present time in a line between Casterton 
and Murray Bridge. This Murray gulf was separated from another marine 
area to the south-east b}^ the Dundas and Grampian ranges, which then 
formed a short truncated peninsula directed to the south-west. 1 The 
Victorian portion of this old Southern Ocean sea-bed comprises the area 
situated between the Grampians and the present coast, and, indeed, extended 
far to the south. It took in the Tertiary districts of Hamilton, Hexham, 
Camperdown and Geelong, forming a wide strait passing north of the Otway 
Jurassic island as far as the eastern boundary of what is now Port Phillip 
Bay. This inland sea was co-extensive with Gregory’s Great Valley of Vic¬ 
toria. 2 The Middle Tertiary sea trended southerly towards Cape Schanck 
and Flinders, whilst the Jurassic island of South Gippsland was but imper¬ 
fectly cut off from the mainland on the north by swamps and lagoons giving 
rise, in all probability, to deposits of lignite. Along its northern boundary 
this Tertiary sea swept to the north-east, across what is now the lake district 
of south-east Gippsland. Evidence of marine conditions in this locality has 
been lately revealed in the Paynesville bore near Bairnsdale. 
1 See fig. 41, p. 406. 
8 Gregory, J. W. Geography of Victoria, revised ed.. 1912, pp. 84 and 87. 
See also pp. 124, 125 for engrafting of the rivers of the Murravian basin. 
