Geology of the Lower Mitchell River. 25 



scattered surface blocks at a much hio;her level on the Bulumwaal 

 road. 



The pebbly drift in the Bellevue quarry is very coarse, and on 

 one side fully 12 feet thick. Many of the larger stones lying on 

 the floor are lenticular in shape, and as much as a foot in length, 

 by eight to nine inches in breadth. On the face of the quarry 

 the stones are of various sizes, and the larger ones mentioned 

 have probably been rejected when the material was carted for 

 road making. 



At first sight it might easily be supposed that the pebble drift 

 is interstratified with the fossiliferous ironstone, as it crops out 

 not only at a higher, but also at a lower elevation even in con- 

 tiguous exposures. In the quarry some few blocks apparently 

 overlie gravel, but this we think is due to slipping. After pro- 

 tracted observation and much consideration, we decide that the 

 gravel drift is younger than the fossiliferous miocene ironstone. 

 Reference to Figs. 4 and 5 will shew our interpretation of the 

 evidence presented at Bellevue. 



As before mentioned, the gravel is wide spread, and is especi- 

 ally displayed in road cuttings south of the river, between 

 Bairnsdale and Lindenow. At the latter locality the river is 

 fordable in summer, and, though a large volume of water is 

 always flowing, the greater part of the channel, which is some- 

 times 300 to 400 feet in width, becomes dry. A large extent of 

 the river bed is thus exposed, and consists entirely of loose stones 

 like those at Bellevue. Similarly at Bairnsdale the gravel is 

 abundant, and has been freely used in making the roads of the 

 shire. On the north of the river the gravel deposits, though 

 fairly thick in places, are less extensive than those on the south 

 side. At Underwood's, as we have seen, and also in a cutting in 

 Dreir's lane, much gravel is present. Again, there is a heavy 

 conglomerate, 10 feet thick, at Skinner's, and another towards 

 Saunders' Bluff, both being terrace deposits. 



The origin of the gravel drift is not in doubt. It is clearly 

 •derived from the waste of the devonian, silurian, and porphyritic 

 rocks to the north. The majority of the pebbles consist of sand- 

 stone, but among them are fragments of porphyry and quartz. 

 Though much weathered, the larger porphyritic pebbles, when 

 fractured, sometimes reveal an internal core of scarcely altered 



