Physiography of Bulla Area. 343 



.favour of their lacustrine origin. There is no evidence as to 

 whether these sands are pre-older-basaltic or post-older-basaltic. 

 The examination of the eucalypt leaves by Mr. R. Patton threw no 

 light on the problem of their age. From their position among the 

 other sandy layers, with which they are conformable, it is probable 

 ^hat they are post-older-basaltic, like the normal Kainozoic grits. 



The beds have a decided tilt to the S.E. This may he due to the 

 .compression of the loose porous sands by the great overload of new 

 basalt, which here is about 140 ft. in thickness. 



(d) Pre-newer hasaltic river sediments. — These are shown on 

 .the map (Plate XXXII. ), as areas where plant stems are very 

 abundant. That they are river deposits is shown by their lenticular 

 -shape, by the small conglomerate that rests on the valley floor, and 

 by the earthy nature of the matrix. They indicate the sites of 

 pre-newer basaltic valleys. 



(e) Inter-newer hasaltic grits and conglomerates. — The lava 

 flows of the newer basalt in this district are divided into two 

 series — Upper and Lower. This will be explained later. Between 

 the two series is the old soil surface of weathered rock, and in 

 places thick deposits of grit have gravitated from the higher grano- 

 ■diorite in the locality into the valleys corroded in the Lower Series 

 of the newer basalt. These grits, etc., are not stratified. Ihey act 

 as a simple division between the two series of newer basalt. The 

 best occurrences are at points marked F on the map. At Column 

 Gully a heavy conglomerate of quartz and basalt pebbles separates 

 the two series, while in the road cutting north of Bulla an old land 

 surface separates them. 



(f) Post-nevjer hasaltic grits, conglomerate and alluvium. — AH 

 •these should be placed as Recent, but as they form only a later stage 

 in the same destructive and constructive process that has been going 

 on right through the Kainozoic, they have been placed under this 

 head. In the neighbourhood of the heart-shaped granodiorite out- 

 ^crop, unstratified grits can be seen both above and below the newer 



basalt. The grits have been shed from the hill. This process went 

 -on before the older basalt, before the neAver, basalt, and it is being 

 continued after it. Grit covers or mixes with the basalt soil. 



In addition to the massive conglomerates that are now being 

 formed in the stream beds, there are conglomerates of much earlier 

 :age formed along the river spurs, especially those of Jackson's 

 Creek, where the deposits are sometimes at least 30 feet in tliick- 

 Tiess. Generally, they are chiefly rounded quartz and basalt pebbles, 

 •and can thus be distinguished from the normal Kainozoic pel)l)le 



