53'^ ,/. T. Jutsun: 



along the main undivided limbs of the Warrandyte Anticline 

 (south-east and west of Warrandyte) the thickness of the rocks 

 on the eastern limb is between 14,000 and 15,000 feet (al- 

 lowing an average inclination of 60 deg.), while on the western 

 (allowing an average dip of 4.0 deg.), it is between 12,000 feet 

 and 13,000 feet. 



Future research, especially in palaeontology, may discover 

 that the beds are repeated by faulting, and this would of course 

 reduce the thickness. The sections, however, on which the 

 estimates are based are very continuous, and faulting is the 

 only feature that could reduce them. Tbe folds are so broad 

 that inversion need not be considered. 



(f) Denudation. 



Judged, by the estimated thickness of the beds forming the 

 Warrandyte Anticline, there has been a minimum denudation 

 at Warrandyte, prior to the dissection of the present peneplain, 

 of over 12,000 feet vertically. 



(g) Character of the Eock-^ from which the Silurian Derived. 



Conglomerates are always of interest in the light they shed 

 on the derivative rocks. At Warrandyte many of the sand- 

 stones and grits contain such an abundance of mica (mostly 

 muscovite) as to suggest their derivation from an igneous rock. 

 No such pre-existing rock outcrops in the district, and the con- 

 glomerates, so far as examined, have not yielded any pebbles 

 of it. The constituent pebbles consist of quartz, quartzite, 

 sandstone, and flint or chert, quartzites and sandstones being 

 perhaps most abundant. The sandstones consist mainly of 

 quartz grains, and so. throw little light on the subject. It is 

 evident theiefore that the rocks which were broken down to 

 form the conglomerates consisted largely, if not wholly, of I 

 altered and unaltered sedimentary rocks. No trace of these 

 has vet been discovered. 



