THE VICTORIAN NATURALIST. 77 



Silurian hills, so that the Merri Creek receives the water from 

 very little beyond the volcanic plain. Near Donnybrook the 

 creek, which has been following the east edge of the plain, turns 

 across it in a south-westerly direction, passing between two 

 points of eruption ; one of these (in Kalkallo, 21) marks the 

 dividing line between the Plenty River and Merri Creek. It is 

 not a large hill, but from the slope of the country it seems, 

 probable that its lava streams are very extensive. The Darebin 

 Creek heads from it, and a note on the geological map gives it as 

 the source of the lava streams to the south. From this point the 

 lava streams extend to the east into the Plenty Valley ; thence 

 southward down a narrow valley in the Silurian rocks west of the 

 present Plenty River, joining the main basaltic area south of 

 Morang ; and it appears not unlikely that the basaltic strip which 

 goes from there down the Darebin Creek and the Yarra to 

 Prince's Bridge may come from the same source. The width of 

 the old valleys here seems quite out of proportion to the streams 

 which flow down them : the Plenty River old valley is represented 

 by a strip of basalt scarcely a mile wide, while on the other side 

 of the Morang Hills the Darebin and Merri occupy a basaltic 

 plain seven miles wide. The Plenty, and all its tributaries that 

 meet the basalt, show extensive alluvial deposits above it, as if 

 their flow had been checked ; and it seems probable that all 

 these tributaries formerly passed to the west of the Morang Hills, 

 and perhaps the Plenty itself turned in the same direction. 



To the west of the Merri Creek, and above the heads of the 

 Moonee Ponds Creek, is another group of four volcanic hills. 

 One of these, in sections 13 and 17 of the parish of Yuroke, has 

 its surface strewn with numerous blocks of scoria and a little ash, 

 with a few ejected blocks of granite and sandstone. Across the 

 top of this hill there are two basalt dykes standing up above the 

 hill. Two other points of eruption occur in section 20 of the 

 same parish, from which creeks run west and north-west to the 

 Deep Creek, south to the Moonee Ponds, and east to the Merri. 

 The lava streams from this hill probably extend round the 

 granitic area to the south, and down the south-west side of the 

 Moonee Ponds Creek. 



In the ranges at the head of the Deep Creek there is a point 

 of eruption — the Jim-Jim, on the top of the Dividing Range — and 

 two others a few miles lower down. In the neighbourhood of 

 Lancefield there are several, and to the south-east, in the parish 

 of Springfield, there are several more. 



South of the Saltwater River, and north of the heads of the 

 Toolern Toolern and Kororoit Creeks, and from there to Diggers' 

 Rest, there is a line of volcanic hills, one of which, Mt. Aitken, 

 reaches a height of 1,680 feet. These are all much denuded ; on 

 some of them indistinct outlines of a crater can be traced. One 



