Physiography of Werrihee Area. 281 



in the basalt, thus leaving the scarp. Thence to the Weiribee, the 

 Parwan flows north-east across the basalt sheet, which it has cut 

 through in its lower part, exposing the tertiary beds below. The 

 last couple of miles are across river flats, and the Parwan then 

 enters the Werribee not far from the junction of the latter with the 

 Lerderderg. 



(d) Pf/ke's Creek. — This creek is marked in most maps as the 

 Korjamumnip, but locally it is called Pyke's Creek in the lower 

 part, after one of the early settlers. It has as tributaries the Kor- 

 jamumnip, Korweinguboora, Dale's, and Korobeit Creeks — all of 

 which have their origin in the high block north of the Greendale 

 fault, along an easterly ridge that runs from near Blakeville to Mt. 

 Blackwood (see Fig. 18). Their valleys probably originated sub- 

 sequently to the Greendale uplift, due to the cutting back of small 

 streams into the scarp face. As they proceeded thus they probably 

 occupied some of the southern territory of the ancient Lerderderg, 

 The influence of the rock structure of the Ordovician beds is shown 

 in all these streams, but more clearly in the case of the Back 

 •Creek, which will be considered later. 



The Korweinguboora Creek rises near Blakeville, and does not 

 now occupy its original valley, which was basalt filled during the 

 newer volcanic period. Just before leaving the ranges, it occupies 

 a deep gorge between this newer basalt tongue and the Ordovician. 

 (Fig. 8.) On emerging from the ranges the river turns eastward 

 along the line of the Greendale fault for about a mile, with a liigh 

 steep scarp of Ordovician on the left bank, and thick, but much 

 lower, deposits of older basalt on the right. It then turns south 

 into the older basalt, in a gently rounded valley, almost treeless, 

 but well grassed, and a mile from the %scarp it joins the Kor- 

 jamumnip. 



Tilt Korjamumnip Creek flows southward from its origin in the 

 ridge mentioned, in a steep, timbered valley. Among its 

 numerous tributaries in the ranges is the Green Hills Ci-eek, a 

 small stream rejuvenated by a basalt flow. Steep valleys <:ontinue 

 to the edge of the scarp, where, like the Korweinguboora, this 

 stream also turns eastward along the fault line, and then south 

 through the older basalts. The distinct nature of the valleys of 

 all these streamsi after crossing the Greendale fault is very marked. 

 Above the fault the valleys are over 500 feet deep, narrow, and 

 V-shaped; immediately below they are at most 150 feet deep, wide 

 and r-sliaped. 'J'here is also the important differences of locks 

 -and soils above and l)elow the fault, already pointed out in otlu^r 



