Account of Glacial Deposits of Bacchus Marsh. Gl 



probably reveal the sources of this material. The .i!;eoloi;y 

 of Victoria has not been so lully worked out as to warrant 

 us asserting that a certain kind oi' rock does not occur in 

 situ. Then again, it must be remembered that these 

 deposits are anterior — as we shall sliow — to the Miocene 

 and Pliocene lava flows, and probably to the Miocene leaf- 

 beds, so that, not to speak of the effects of denudation, a 

 a great deal of the then rock surface is now concealed. 



Of the various kinds of rock met with in the till in the 

 Bacchus Marsh district, the gieat majority are derived from 

 Silurian rocks, which form the main part of the Dividing- 

 Range. In the Werribee Gorge several kinds of slate occur, 

 which are identical with slates found in the till. Quartz 

 veins are als(^ numerous in the Silurian rocks. We also 

 noted a quartzitic sandstone in the Gorge, which is very 

 similar to fragments found in the till. Several varieties of 

 quartzite occur in the till which we have not yet seen in 

 situ, but we have not yet examined the Ranges to the north, 

 and it is very probable they will be found there, as quartzites 

 frequently occur in the Silurian. Fragments of schist(;se 

 rocks have also been observed in the till, and these occur 

 in situ to the north. 



Several kinds of granite occur in the till. Granite is 

 i'onnd in situ in the localit}^ and among the granite boulders 

 some occur that seem identical with this gianite. A very 

 coarsely cr^'stalline variet}^ is also met with, the crystals of 

 felspar being sometimes over an inch in length. Though we 

 ourselves have not seen this in place, 3'et the Geological 

 Surve}' report a granite with very large crystals of felspar 

 as occurring in this locality. Pegmatite and aplite also are 

 found in the till. As both of these may occur as veins in 

 other granite, it would not be surprising if they have been 

 overlooked. It is not unlikely even that they may be now 

 concealed beneath the basalt that is well developed in this 

 distiict. 



Summing up, then, the results of our investigations, it 

 would appear that two main points are clearly brought out. 

 The first of these is, that there are two distinct glacial 

 deposits ; and the second, that both of these deposits are 

 due to glacier ice, and not to icebergs — in fact, both being 

 moraines profondes. Both are of similar character, except 

 that the lower one is more indurated and jointed. Of these, 

 the latter has been seen to closely enwrap the smoothed, 

 grooved, and furrowed surftices of Silurian rocks, of the 



