f 



REPORTS OF RESEARCH COMMITTEES. 317 



basalts, and he considers these lavas must be Kalininan or younger. 

 The Kangaroo Ground sediments and covering basalt are provi- 

 sionally placed with similar rocks at Greensborcugh. Since the 

 basalts at Kangaroo Ground and elsewhere are younger than the 

 Nillumbik Peneplain they cannot be ccneidered monadnocks. It 

 is inferred that the intermediate basalt was poured out before or 

 shortly after the uplift of the Nillumbik Peneplain. 



R. A. Keble has furnished a valuable paper on the mapping 

 of the older river systems of Port Phillip and Western Port by a 

 study of the lava residuals (12). In this work he defines three 

 cycles of the Older Basalt residuals — (a) the pre-older Basalt 

 cycle, (b) the Older Basalt cycle, (c) the Intermediate cycle. Also 

 in the development of the Newer Basalt^ residuals there are three 

 cycles — (c) the Intermediate cycle, (d) the Newer Basalt cycle, 

 {<') the post-Newer Basalt cycle. This paper opens up maxiy 

 questions which are of the greatest interest toi the palaeogeographer. 



The great uplifted peneplain of Victoria, with its tilted bloicks 

 and fault-scraps of vaiying ages, has been dealt with from various 

 aspects by Hart (1 and 7), Fenner (3 and 13), and Teale (15). 

 Mahony (5) and Fenner (13) have endeavoured to reconstruct the 

 story of the various tectonic movements of later Tertiary time that 

 have dominated the formation of the present surface features of 

 the State. The latter author has described in detail three Vic- 

 torian rivers, the Upper Goulburn (3), the Glenelg (11), and the 

 Werribee (13). In the first-named paper the interesting sunk- 

 land of Mansfield has been described. The upper portions of all 

 three rivers are entrenched in the uplifted and tilted peneplain of 

 Victoria, the old surface of which now slopes gradually tO' the 

 westward from a height of 6,000 feet in the case of certain Upper 

 Goulburn tributaries, down to a few hundred feet above seia-level 

 in the case of the Upper Glenelg. This uplifted and dissected 

 peneplain, mainly of Palaeozoic, highly-resistant rocks, is regarded 

 as a mosaic of faulted blocks, dift'erentiallv uplifted and depressed. 

 The faults are chieflv n^eridianal, intersected by another series 

 trending east-west. The most detailed investigations were carried 

 out in the Werribee River area, where the Greendale and Spring 

 Creek faults (east-west) were shown tO' be clearly pre-newer basaltic, 

 whilst other east-west faults of greater age were demonstrated. 

 The meridianal fault of Bacchus Marsh, 30 miles in length and 

 with a maximum movement of about 1,000 feet, was demonstrated 

 on geographical and physiographical evidence. This fault is in 

 part, in its latest movement, post-newer basaltic, and may be 

 associated with the last great movement of uplift of the peneplain 

 (Kosciusko epoch). The Bacchvis Marsh fault forms the western 

 boundary of the great and important Melbourne Sunkland, which 

 is in part occupied by Port Phillip Bay, and is bounded on the 

 eastern side bv Selv/vn's fault. 



