Physiography of Wermhee Area. 



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As the Lerderderg flows on through the ''flats/' it is bounded, 

 at some distance, on the right bank by the treeless, residual ridge 

 of Bald Hill (glacial and older basalts) and on the left bank by the 

 sands and clays of the tertiaries, overlain by the tongue of newer 



i^;^ 



Ci 



Fig. 29. — Plan of terraces on the Lerderderg' River, near Kerr's farm, 

 above Darley. 



basalti that filled the '' Ancient Buriengarook '^ Creek. Ordovician 

 is exposed in the bed of the creek at the Darley Bridge. An impor- 

 tant tributary, Goodman's Creek, coming from the north, enters 

 about a mile above this bridge. While this part of the river is 

 referred to above as '' older " than the upper Lerderderg, it is of 

 course only so im form. As a matter of fact this mature valley, in 

 soft rocks, is post newer basaltic in age, and from the point of view 

 of time, much later in origin than the portion of the valley in the 

 ranges. From Roljertson's Creek, right down to the town of 

 Bacchus Marsh, the western side of tlie valley, between the present 

 bed and the Bald Hills, is covered by thick terraced deposits of 

 coarse pebbly alluvial, standing at high levels. For the last mile 

 of its course, the river runs parallel with the Werribee, in a simi- 

 lar channel, in deep alluvium, and joins that stream near the 

 eastern end of the Bacchus Marsh basin. 



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