244 Proceedings of the Royal Society of Victoria. 



Tertiary series of rocks consisting of gravels, sands, clays, and 

 sandy and ferruginous clays, formerly regai-ded as of Pliocene, but 

 now as either of Miocene or Eocene age. In the index to the 

 plan I have referred to these beds as Older Tertiary. They 

 form portion of a series of beds that extends across a large part 

 of the Mornington Peninsula and South Gippsland. For almost 

 the whole distance through the locality the river runs near 

 the sovithern bank by reason of a narrow strip of basalt that 

 occupies the valley. This flow of basalt has apparently filled 

 up the original course of the river and has caused it to im- 

 pinge against the steep Silurian banks on the south. Probably 

 the basalt reached the foot of these cliffs and necessitated the 

 river having to cut its way through it. But, as the sedimentary 

 rocks would under these circumstances be the more easily eroded 

 the new channel would be formed on the Silurian side, thus 

 accounting for the fact of basalt occurring only in one small 

 patch on the south side of the river. 



From Queen's Bridge, which is about 30 chains below Prince's 

 Bridge, the western limit of the map, to past the City of Rich- 

 mond quarries, some 25 chains above the eastern limit, basalt 

 may be seen in or near the northern bank of the stream for 

 nearly the whole distance. At only one spot, however, as 

 already stated, near the Botanical Bridge, is it noticeable in the 

 south bank. 



It appears at the surface either as rounded masses of a few 

 feet in area, as large loose fragments, or under a varying thick- 

 ness of alluvium as disclosed by shafts and other artificial 

 sections. It is a rather coarse variety and chiefly vesicular and 

 amygdaloidal. The cavities contain the common globular calcite, 

 though in the quarries at Richmond, where there is a thickness 

 of close on 100 feet of this rock, there occur in addition ferro- 

 calcite, aragonite, and various zeolites, such as phacolite, phillip- 

 site, herschelite, and mesolite. Field geology, and the numerous 

 shafts put down by the Metropolitan Board of Works during the 

 last three years in Richmond and Jolimont, in connection with the 

 sewering of the metropolis, show that the basalt extends consider- 

 ably to the north of Swan Street, Richmond, past the Richmond 

 and Melbourne Cricket Grounds along the edge of the Silurian that 

 embraces most of Yarra Park, round the foot of Jolimont Street, 



