Pliy^iiogrdpJtu of t/ie Mansfield Dintrict. y9i> 



It is interestiug tu note that the post-ord., post-silmiaii. and \>nsi- 

 lower-fai'buiiifeious deformations appear, in this aixa. in ha>e con- 

 sistently folded the beds with X.W.-S.E. axes. 



The general trend of the tertiaiy crust movements here are more- 

 dithcult to determine. The reading of the recent physiographic 

 history is greatly retarded Ijy the absence of a reliable contour maj). 

 Since physiography is a science of mucii economic value, it may 

 be fitting here to add another voice to the increasing demand for a 

 Federal Contour Survey. 



The upper Goulburn Valley has already been discussed in this 

 paper, and evidence has been adduced toward proving that the 

 present ujjper Goulburn consists of the headwaters of two original 

 northward-flowing streams. By means of the diagrams (Figs. 13- 

 to 16), endeavour will be made to elaborate this theory. While 

 there is no doubt that differential denudation has played a large 

 part in the formation of this valley, it is very proVjable that another 

 factor was block-faulting, similai' to that proved by Hart for the 

 western part of the Victorian Divide, and similar also to that which 

 has dominated the physiography of the neighbouring area of south- 

 eastern New South Wales. (Taylor.) Jutson has also shoAvn that 

 faulting has played a part in the formation of the adjacent valley 

 of the Yarra. 



The inharmonious arrangement of the Goulburn and its tribu- 

 taries has already been pointed out. The sharp northward bend of 

 the Broken River at Barjarg (Fig. 2) has been noted by many 

 physiographers; old maps of Victoria, indeed, show that certain 

 cartographers had rearranged the mountain chains^ in order to 

 make this feature look more normal. Further, the discordant 

 nature of the windings of the lower Delatite before entering the 

 Goulburn (Fig. 1) is surely significant of some important crustal 

 movement. We may accept the main divide of Victoria as being 

 a physiographic feature of very long standing, say, back to early 

 tertiary times. Of this physiography we have some remnant in the 

 older basalt cappings of central and eastern V^ictoria. From such 

 relics, of whose relative heights we have unfortunately little know- 

 ledge, it would seem to be an impossibility to reconstruct, even 

 very roughly, those ancient river systems. Especially so, when we 

 consider the disturbed state of eastern Australia in late tertiary 

 times, and the fact that, as shown in Fig. 8, streams such as the 

 Howqua have eroded their valleys over 4000 ft. in very hard rock 

 since the older basalt period. 



1 Map of Victoria by J. Bartholomew. 



