ALKALI ROCKS OF DUNDAS, VIC. 135 



Permo-carboniferous. — Mr. Ferguson^ was the first to record the 

 occurrence of glacial beds in this area, and these beds were more 

 fully described later by Mr. Hogg.^ One very good section not 

 mentioned by the above author is to be seen in a river cUff section 

 near Coleraine. A considerable thickness of glacial material is here 

 ■exposed, and striated boulders are fairly common 



Mr. Hogg discusses the ages of these beds, and although making 

 the statement that the glacials appear to occup}^ a pocket in the 

 trachytic rock, concludes that they belong to the Permo-carbonife- 

 rous, and there is little doubt that this is their correct position, 

 although direct evidence is not forthcoming. At Mt. Koroite the 

 simplest reading of the succession is as follows : 

 Tertiary sands, etc. 

 Trachytes and associated basic rocks. 

 Jurassic sandstones. 

 Glacial beds. 

 It should be added that the glacial is only exposed low down on the 

 flank of Mt. Koroite, whereas Mr.Dennant^ records the occurrence of 

 Otozamitcs from near the summit, so that the inference is that the 

 Mesozoic overlies the glacial. 



Jurassic. — A glance at the Geological Survey Map of Victoria 

 ■will show that a considerable area to the south of Coleraine and 

 •Casterton is occupied by rocks of Jurassic age. From the point of 

 view of the present paper the main interest centres round the 

 relationship of these beds with the trachytic rocks of Mt. Koroite, 

 where the two occur associated with one another, but discussion of 

 ihis relationship is reserved till later in the paper. 



Tertiary. — The author considers that the alkali series belongs 

 to the Tertiary Period, but reasons for this view, together with 

 ■descriptions of the rocks and their occurrences, are given later. 



Ferguson has recorded fossiliferous deposits from various places 

 within the area, but the only fossil mentioned is Trigonia semi- 

 undulati. He states that the fossils have a Miocene aspect, so 

 that taking the above fossil into account it is probable that the 

 limestones at least are Barwonian in age. (Note. — ^The Miocene of 

 the Surveycorrespondsto the Eocene orBarwonian of some authors.) 



Unfortunately these fossihferous beds are not known to come 

 into contact with the alkali series, although at Koolomer the two 

 are not far apart. 



The Upper Tertiary deposits which cover the higher parts of 

 the district consist mainly of sands and clays, and have so far proved 

 unfossiliferous. The character of the material is such that fossils 

 would not readily be preserved, so that their absence does not 

 necessarily signify absence of marine conditions, and the widespread 

 deposition of these beds overlying fossihferous beds certainly points 

 to a marine origin. 



1 op. cil., p. 59. 

 •2 Op. cit., p. 358. 

 3 Op. cit., p. 395. 



