Vol. XXVII, 



1910 



1 Armitage, Country about West Essendon. 



in the underlying rock material. This sequence of events might 

 possibly occur repeatedly, on each occasion some remnants 

 of each flat valley-floor remaining on one or other side of the 

 present valley at various elevations. These would constitute 

 a series of river terraces, the oldest being situated at the 

 highest elevation on the flanks of the valley, the younger being 

 lower, and the most recently formed being found just above 

 present stream level. Seven such terraces can be perceived on 

 the south side of the Saltwater River at the Horseshoe Bend at 

 the following elevations — viz., No. i, 94 feet ; No. 2, 64 feet ; 

 No. 3 (to be seen on both sides of the river), 40 feet ; No. 4, 

 32 feet ; No. 5, 24 feet ; No. 6, 18 feet to 13 feet ; No. 7, 

 6 feet. These are unsymmetrical terraces, being confined to the 

 south side only (with the exception of No. 3), at the Bend, the 

 river having corraded its bed mainly toward the north side of 

 its valley, persistently shifting its channel to that side, with the 

 result that the constant undercutting has caused the formation 

 of the steep-faced river-cliff on the north of the Bend. 



This successive arrival at a state of maturity and then re- 

 juvenation, indicating alternating pauses and renewals of a 

 river's vertically corrasive activity, as evidenced by the forma- 

 tion of river terraces, is so commonly to be noticed in connection 

 with stream valleys in the vicinity of Melbourne as to point to 

 minor oscillations in level of the earth's surface as their ultimate 

 cause. At the present time the Saltwater River is a tidal 

 stream, and therefore dead, from a point some miles above the 

 Horseshoe Bend to its confluence with the Yarra River at Foots- 

 cray. The Yarra River is in a similar condition naturally, up 

 as far as Queen's Bridge, where rocks forming " The Falls " of 

 the early days have been removed by man. This removal has 

 allowed tidal conditions to obtain almost up as far as Johnston- 

 street Bridge, Abbotsford. The lower part of the course of the 

 Moonee Ponds Creek exhibits the same feature. This drowning 

 of the lower parts of these rivers indicates that the latest crustal 

 movement of the country in the vicinity of Melbourne is one of 

 subsidence, which probably is still in progress. 



The Older Volcanic Basalt. 



Although the Quarter Sheet shows an extensive area of Older 

 Volcanic covered by a thin mask of Tertiary deposits, yet good 

 exposures can be seen only where stream or road cuttings have 

 been carried down some distance into this so-called capping. It 

 would be better were the mapping of this area revised, so as to 

 show more truly the actual rocks outcropping at the surface 

 Along Buckley-street west towards the Horseshoe Bend no 

 Older Basalt is actually met with until almost at the boundary 

 of Essendon city, where a slight exposure of some very much 



