294 Charles Fcnver : 



Beyond sections 7 and 8 this stream junctiuned with the 

 *' ancient Myrniong,'' and turned southerly to where sections 9 and 

 10 are exposed in the Myrniong, (Fig. 34). These have already been 

 fully described; the Myrniong has not yet completely cut through 

 this " tongue." 



The ancient Werribee then turned eastward, and for tlie next 

 mile its basalt filling has given rise to the well-known " Island " 

 (see Fig. 20). Section No. 11 is shown at the eastern end of the 

 Island, and a gap of one mile then occurs between sections 11 and 

 12. This gap is caused by the extensive erosion of the Werribee 

 •Gorge, but at least four small relies of basalt may be found along 

 the line of the ancient valley here. A critical inspection of this 

 rugged and difficult area from various viewpoints, and an examina- 

 tion of levels bring one to the conclusion that the course of the old 

 river was approximately as shown by the arrows in Fig. -36. The 

 'old valley here was in Ordovician and glacial rocks. Section No. 

 12 is somewhat obscured by hill-slip material, but basalt occurs 

 in situ at ai low level, and from this point soutli-easterly the evi- 

 dence of the sections may be linked up Avith that of the tongue 

 exposed at Dog Trap Gully. 



The whole of the available evidence from these sections is summed 

 up in Fig. 36, and the course of the ancient Werri]>ee is shown by 

 a series of arrows, extending from section 1 and 2, right along to 

 the scarp at Dog Trap Gully, a distance of eleven miles. 



This knowledge has also been included in Fig. 35, and the rivers 

 there marked by lines of arrows (both continuous and broken) show 

 the pre-basaltic river system as far as the writer could determine it. 

 While there are still many gaps, it is clearly shown that the river 

 i5ystem was, south of the Greendale scarp, in an area of fairly low 

 relief, with a general south-easterly trend. 



(c) The Plains and Swamps. — Plains form no pait of block A 

 ^the Blackwood and Lerderderg Ranges), nor of the eastern part of 

 block C (the Brisbane Ranges), nor yet of l:)lock D (the Gisborne 

 highlands). 



Blocks B. and E. however, the Ballan and Port Phillip sunk- 

 lands, are mainly plains. The only extensive level areas are those 

 •of a constructional type, built up either of — 

 (i.) Volcanic sheets, 

 (ii.) Alluvial material. 



(i.) Volcanic Sheets. — The wide, open, grassy plains north and 

 south from, Ballan are of volcanic material. They were once much 

 more extensive, and are being gradually destroyed by the rivers. 



