THE VICTORIAN NATURALIST. 83 



these still retain the basaltic cap, they look like huge steps or 

 terraces. 



Striking north about six miles the sections on Pyke's Creek are 

 seen ; they rest on Silurian and Glacial Drift, and resemble those 

 on the Werribee and Parwan Creeks, viz. : white and yellow 

 clays, sand, ferruginous sandstone, quartz gravel containing gold, 

 and a dense quartz conglomerate. In the white clay a large 

 proportion of common salt is present, so much so that sheep and 

 cattle have, by constantly licking, hollowed out small caves 

 several feet in depth. Many of the pebbles in the quartz gravels 

 have a glass-like polish, probably a secondary deposit of silica. 

 Following the main road east the clay beds thin out, their place 

 being taken by current bedded quartz gravels, sand, and sharp 

 quartz grits. South of Myrniong the beds rest on granite, and 

 have been worked for gold, yielding fair returns to those engaged 

 upon them. Zircon, sapphire, and quartz crystals occur, together 

 with blocks of petrified wood. Between Myrniong and Lyell's 

 Creek typical sections of the Miocenes are exposed in the 

 cuttings on the main road, and also to the west of Lyell's Creek. 

 The general dip of the beds under notice varies from 2 to 14 

 east, their thickness being not far short of 400 feet. In the 

 area under notice they occur at any level between 300 and 1,900 

 feet ; or, in other words, follow the general surface slope of the 

 older rocks. To the north and north-west of Myrniong the 

 Miocenes thin out considerably. The highest point at which these 

 beds have been observed within this district is on the north-west 

 base of Mount Blackwood, where sharp grits, fine quartz con 

 glomerates, and ferruginous grits occur. Reference has been 

 made to the sudden rise in the basaltic sheet to the west of 

 Bacchus Marsh. Probably we have here an old coast line, or 

 evidence of elevation during Miocene time (?). That a con- 

 siderable period elapsed between the laying down of the 

 Miocenes and the flow of Newer Basalt is shown by the depth of 

 the old river channels. Some of these have cut through the 

 overlying Miocenes and then into Granite for a depth of over 

 170 feet. Channels of greater depth are seen, one being about 

 350 feet. 



The depth of the Pliocene (?) river beds, compared with the 

 present drainage system, is about one-half. In several instances 

 the rivers and creeks have cut these old channels at various 

 angles, exposing the old river drift. These latter are generally 

 of dark colour, and contain the remains of numerous plants, 

 which are quite distinct from those found in the Miocenes. 

 Some of the leaf casts in the old river drift resemble the leaves 

 of our present "gum trees." The courses of the old rivers can 

 generally be traced by flat-topped ridges of basalt. 



Contrary to what one would expect in a district which has 

 passed through such violent volcanic disturbance, dykes of 



