Geological Structure about Mornington. 41 



beds represent the marine eocene, then they should be subsequent 

 to the basalt. 



The alternative explanation is that there really was a consi- 

 derable lapse of time between the deposition of the lignitic series 

 and the overlying beds, and that the basalt represents a denuded 

 portion of a sheet which has almost entirely disappeared, and 

 that, after its partial removal, the sandy beds were laid down, 

 partly on the lignitic series and partly on the basalt. The 

 passage of the beds in this case would be only apparent, and 

 due to the fact that the first-formed portion of the upper beds 

 was derived from the waste of the lower. This explanation is 

 the one we adopt. 



Succession of the Rocks. 



We give the following as, in our opinion, the sequence of the 

 beds : — 



Bleached sands, clays and alluvium - - Eocene to Recent. 

 Ferruginous grits, sands and clays - - | 

 Blue and grey clays and gypsiferous sands V Eocene. 

 Basalt - - - - - - - ) 



Slaty conglomerate and lignitic beds - 1 Eocene. 



Shales and sandstones . - - - Jurassic. 

 Granitic rocks. 

 Slates, ikc. ...... 1 Silurian or Or- 



dovician. 

 Silurian or Ordovician ? 



The series of highly-inclined rocks is clearly antecedent to the 

 granitic I'ock, as small dykes and sills of the latter occur in the 

 Moorooduc quarry. Hitherto we have been unable to find any 

 fossils in these rocks in situ. The coarse conglomerate which 

 underlies the basalt in many places appears to be, in the main, 

 derived from the older paleozoic sedimentary rocks of the district 

 and from the granitic series. In two places, namely, in the first 

 cutting on the coast road south of Frankston, and near the first 

 outcrop of granitic rock south again from this place, on the 

 shore we have found a few graptolites in slate pebbles. They 

 are very indistinct, and, beyond saying that they are species of 

 Diplograptus, we do not at present care to venture. Their 

 evidence, then, leaves the age of the rocks still open. 



