180 Proceedings of the Royal Society of Victoria. 



The measurements just quoted show that the boulder bed is 

 separated from the underlying eocene clays and limestones by not 

 less than ninety-five feet of basalt, that is, from the outcrop of 

 the latter at the base of the section to the first appearance of the 

 conglomerate up the' hill ; moreover, from the fact that the 

 quarry alluded to is situated at a lower level than the boulders, 

 we may fairly infer the continuance of the igneous rock beneath 

 them for their whole extent. If, in excavating the quarry, the 

 fossiliferous boulders had been revealed, a different conclusion 

 would be possible, as in that case they might simply represent 

 a miocene inlier, surrounded and partially covered by a subse- 

 quent flow of lava. Such an explanation is, however, inadmissible, 

 as they are not only absent there, but, as we have before said, do 

 not show in any cutting or natural section along the river bank : 

 and we are therefore driven to seek some other interpretation of 

 the facts. 



At Muddy Creek, as is well known, miocene strata are covered 

 by a lava flow, usually regarded as of pliocene age, but that this 

 was contemporaneous with the basalt overlying the eocene of 

 the Leigh River, is, independently of the fossil evidence now 

 presented, open to doubt. It is generally admitted that in the 

 eocene, pliocene, and perhaps also the pleistocene periods, out- 

 pourings of lava took place over various portions of Southern 

 Australia, but with one exception, the authors of recent memoirs 

 on our tertiaries refrain from classing any of the basalts as 

 miocene. If, howevei', the fossiliferous boulders of the Shelford 

 section are miocene, the lava upon which they rest, may, provi- 

 sionally at least, be referred to the same period — certainly it 

 cannot be younger. Our theory, in fact, is that the Shelford 

 basalt is a miocene flow covering the wide spread eocene strata 

 of the region. Then, after the channel of the river had been 

 partially excavated, the miocene conglomerate was deposited 

 either in a slight depression hollowed out of the basalt, or upon 

 its gently sloping surface. It is not unlikely that this portion of 

 the Leigh River represents an old estuary connected with the 

 former sea-channel, which, as pointed out by Mr. Murray, existed 

 in tertiary times between the Cape Otway Ranges and the main- 

 land to the north.* As the deposition of the boulders commences 



* Geology and Physical Geography of Victoria, p. 122. 



