78 Proceedings of the Royal Society of Victoria. 



Buninyong basalt stream and to that on Mount Buninyong 

 itself, in which olivine is extremely common, particularly in 

 vesicular materials. 



Webb's Hill and these two ridajes would seem to represent 

 the remnants of an old volcano. The extension of the volcanic 

 material to the west would naturally be expected to occur 

 under the Buninyong basalt, and the volcanic ejectamenta 

 there found with these surface materials, perhaps represent 

 successive eruptions from different vents. The present dis- 

 position of the sui'face volcanic material would favour a vent 

 nearer "Webb's Hill, or between it and the No. 1 shaft. 



At the south-west corner uf the Buninyong Estate the lava 

 streams are easily distinguishable into three, differing in appear- 

 ance, usually in a very marked degree. 



In the bed of the Yarrowee Creek is a dark, compact lava, 

 with much porphyritic augite and little olivine visible, which 

 agrees with Messrs. Murray and Etheridge's description of what 

 they name the Durham Lead flows^ It appears to be their 

 Upper Durham Lead flow. It is seen higher up at Scotch- 

 man's Creek, but further I have not investigated its continua- 

 tion. It extends down the Durham Lead below. Similar 

 basalt occurs in the blocks in the ash on the north spur from 

 Webb's Hill and in the ejectamenta of the No. 1 workings. 



Overlying this on both sides of the Yarrowee Creek is a 

 paler and coarser textured lava, without any visible olivine or 

 porphyritic minerals, and similar to that which occurs on tiie 

 western volcanic area of Ballarat — subsequently referred to as 

 the Yarrowee lava. This appears to be close to its southern 

 end, and not extending much further. The Buninyong lava 

 stream is characterised by the extreme abundance of olivine, 

 often in large lumps of '2in. or more diameter in the vesicular 

 portions. This character is found invariably from the town- 

 ship across Buninyong Estate to a low bank running parallel 

 to the Yarrowee at the west side of the Buninyong Estate 

 and another low bank near the mouth of the Devonshire Creek, 

 both marked on j\Ir. Murray's map. Between these it reaches 

 the Yarrowee for a short distance, but never crosses it. 



1 Ueolog-ical Survey of Victoria, Progress Report No. 2. 



