■288 Charles Fenner : 



two " breaks," with steeper grades, apparently due to the two 

 E.-W. faults that lie in its course. 



(i.) Djerriaxtrrh and Toolern Creeks. — These tMo streams did 

 not receive the close attention given to other streams described. The 

 Djerriwarrh is locally known as Deep Creek, and the Toolern is 

 shown in some maps as the Toolam Toolern. The Djerriwarrh 

 receives a fairly important tributary — Boggy Creek — on its right, 

 while the Toolern receives Condon's Creek (sometimes called Yan- 

 gardook Creek) on its left. Their grades, as shown in Plate XIIA., 

 and their general appearance in the field, bear witness to rejuvena- 

 tion in their upper portions. In this rejuvenation differential 

 uplift and lava flows have each played a part. 



The Djerriwarrh Creek lies Avholly in Ordovician, except where 

 its extreme upper tribuaries flow over the Gisborne basalts. Its 

 profile (see Plate XIIA.), indicates that while it is wholly in 

 •Ordovician rocks, as far as known, yet these rocks stand at two 

 <listinct levels; this profile has been already used as evidence in 

 favour of a fault junction separating the higher deeply-dissected 

 Ordovician, from the low relief area to the south. On the evi- 

 dence of the contour maps, and without having personally 

 -examined that particular portion of its course, the wiiter would 

 point out the high possibility of the head gullies of the Djerri- 

 warrh Creek having been captured V>y the Pyrete Creek. 



The Toolern Creek in its head gullies has partly cut through the 

 basalts to the Ordovician bedrock, but the greater part of its 

 course lies on the newer volcanics. The writer travelled along it, 

 but found no features of particular interest. Where it passes 

 through the township of Melton, on the Melbourne-Ballarat road, 

 its valley is scarcely perceptible, but it rapidly deepens after cross- 

 ing the railway line, and enters the Werribee at Exford in a steep- 

 sided valley, wholly basaltic. 



(iv.) The Buried Rivers. {Pre-N ewer-hasaltic.) 



We have no means of discovering the nature of these old river 

 courses beneath the volcanic plains of the Port Phillip sunkland. 

 The bores put down in and near the township of Melton suggest 

 that " deeper ground ' exists from the Djerriwarrh Creek towards 

 the Toolern Creek, but the sub-basaltic area here was evidently of 

 very low relief, with Avidespread gravels and clays; and no definite 

 valleys were detected. Bores and sliafts at Altona Bay and New- 

 port s'linw that, under the basalt, there are hundreds of feet of 

 tertiary material, marine and fluviatile, with ])edrock at about 400 



