158 /. T. Jutson: 



which now run into the Yan Yean Reservoir, had tlieir outlet. It 

 will be noticed that in this locality the Plenty has a narrow north 

 and south ridge on each side of it, and that on the opposite side of 

 each ridge a stream runs parallel to the Plenty. The eastern 

 stream rims into the Reservoir, and the western one turns to- 

 wards the south-east to join the Plenty, which (judged by the line 

 of outcrop of the silurian on its north-eastern side), it apparently 

 did prior to the basalt flow. 



A point in favour of the capture is the continuous basalt 

 north of the Morang Hills, from the Plenty for several miles 

 to the west, which might indicate an old valley and a swing 

 round to the west of the old stream. But when it is remem- 

 bered that whole ridges of low elevation must have been buried 

 by the basalt, such a ridge, separating the tributaries of the 

 old Plenty River and Merri Creek, may have existed here. 

 If capture had taken place before the basalt was erupted, then 

 part of the old Plenty south of the point of capture would be 

 turned northward, and a low ridge separating such northward 

 flow from the stream below might lie buried near Morang. So 

 far as lam aware, nothing is known of the thickness of the basal 

 in the main part of the valley at Morang, and farther north ; 

 so that this point cannot be proved or disproved at present. 

 In addition the development of the old valley between Morang 

 and the point of capture could not be accounted for (this north- 

 ward stream being too short for such work), unless it be as- 

 sumed that such development took place wholly before capture. 



Without further consideration of the possible changes in the 

 old Plenty, it is clear that when the newer basalt was poured 

 out, a valley existed to the east of the Morang Hills, down which 

 this basalt flowed ; and meeting the flow from the west, spread 

 out south of the Morang Hills into a broad sheet stretching to 

 the west for several miles, and also to the south, partly fllling the 

 old valleys now occupied by the Darebin and Merri Creeks. The 

 country to the east of this main sheet of newer basalt is more 

 elevated than the latter (except between Janefield and Morang, 

 where the different formations are on much the same level). 

 This elevated country consists of older basalt, silurian, sandstones 

 and shales, and tertiary grits and gravels, and its western boundary 

 ^s really a continuation of the eastern side of the old Plenty valley 



